~~~~~~~School Bus Mechanic

Cat 3116 Diesel Engines

2009-10-10T20:21:00.000-07:00

I've been getting a lot of questions on 3116 Cat Diesel Engine problems. The one stumbling block is the tooling you need to repair these model engines. After the basics like fuel supply and electrical issues are taken care of the next step is replacing injectors and other related tasks.

The tools required for tuning up these engines come in a kit and costs over $2000.00 in my part of the world. These tools must be used to get this engine synchronized, timed and set up properly.

If you have access to the tools that's great, a manual accompanies the kit. There is a learning curve with setting up the 3116 but do it once and you'll understand the concepts behind the injection system.

There are glitches with the 3116 are usually the same and I have posted them as they happened on this blog. The exhaust valves are weak and it seems like #5 exhaust valve is a weak spot. Keeping the valves set is a good practice and prevents a tight valve and overheating.

If you use the search box above you can get more details on tune ups and repairs. There are specific rebuild procedures covered as well.

Or you can check all the posts out here:

http://schoolbusmechanic.blogspot.com/search?q=cat+3116

You might have to be more specific with your search i.e "cat 3116 oil pump"

You can always make a comment or ask a question and I will get back to you...

Air Brake Theory Revealed

2009-09-21T21:20:00.000-07:00

Here is an excellent video on air brakes. This is the best presentation I've ever seen that will give you a detailed overview on exactly how air brakes work. The air brake mechanical and air systems work together. This video is referring to a school bus but is the same brake system found on most transport vehicles.

If The Video Doesn't Show Up in Internet Explorer Get To It HERE

The cutaways and detailed views of the air brake system explained here will help you understand the principles and terminology that you need to know. There are many things that happen in air brake systems like moisture that builds up from the heat that is generated from the compressor.

This is why draining air tanks daily is very important especially in cold weather conditions. This is a lot of information to absorb but the power of video allows you to watch it more than one time.

Making Biofuel From Trees In Costa Rica

2009-08-09T08:16:00.001-07:00

A Reusable Method For Producing BioFuel From Trees?

BioFuel trees produce seeds that are rich in oil. Crushing these seeds in a simple mechanical press releases the oil, which can be filtered to a tight specification and stored. This oil is referred to as Pure Plant Oil (PPO) or Straight Vegetable Oil (SVO) and is the base material for Diesel substitution.

As a BioFuel, tree-based Pure Plant Oil has significant advantages over crop-based Pure Plant Oil like Soya or Rapeseed: BioFuel trees grow on land that is unfit for food production or where Rain Forests can not and should not be removed. The oil from BioFuel trees is inedible. This means that the use of tree-based Pure Plant Oil for BioFuel does not compete with food production or edible oil supply.

Pure Plant Oils tend to be more viscous than Diesel, but can be used directly in modern Diesel engines with technology like that supplied by UK-based Regenatec, which designs and sells some of the world’s most advanced Diesel engine conversion technology.

The other option is to chemically process PPO in a refinery into what is commonly called “BioDiesel” and blend it with Diesel for regular use in vehicles.

Read Full Article http://wizetrize.wordpress.com/2009/07/15/biofuel-trees-wizetize-is-invested-in-in-costa-rica/

Diesel & Gasoline Working Together?

2009-08-07T22:14:00.000-07:00

The Wartsila-Sulzer RTA96-C turbocharged two-stroke diesel engine pictured has a thermal efficiency of 50% (the best in the world). There is new research going on in the University of Wisconsin, Madison that got 53% thermal efficiency out of a Cat Diesel Engine.

I just read the article about this new technology mixing gasoline and diesel into a diesel engine. This system increases the thermal efficiency by 20% but reduces the temperature in the combustion chamber by 40% creating less unburned fuel out the tail pipe.

The mix would be computer controlled and since there would be less energy loss through heat transfer, improved combustion would cause an increase in power with less emissions.

The computer age has allowed scientists and researchers to stretch the resources we have right now to the limit in a very efficient way. Without computer programming, monitoring, and adjusting operating parameters this new technical solution for decreasing vehicle emissions would not be possible.
I hope you found this Mechanic Information interesting...

Motor Coach Industries Free Webinar Training

2009-07-26T15:40:00.000-07:00

For all you Motor Coach Mechanics Motor Coach Industries as you probably know as MCI is offering free motor coach training as Webinars. All you need is your computer and the proper application to get into the training.

In September they are offering hands on technical training:

SEPTEMBER 22-25 Technical Tune-Up
MCI NATIONAL TRAINING CENTER, Louisville, Kentucky

MCI Driver training Simulator

You can select from a variety of pre-designed training scenarios or customize a program to meet the needs of your business. The MCI Coach Driving Simulator is available for purchase or lease.

The MCI Coach Driving Simulator offers state-of-the-art features that include:

•A highly realistic and immersive training environment that creates the look and feel of an actual vehicle.
•Precision motion platform for a realistic driving experience.
•Steering with real-time feedback.
•State-of-the-art software that delivers sharp, crisp images.
•Special effects that simulate extreme conditions such as mountain driving, snow, heavy rain, fog, ice, and varying wind conditions.

MCI also offers driving guides, parts and maintenance manuals on CD.

I've never seen a company that offers so much support to technicians and drivers involved in this industry. I think it's great for Mechanics to have this resource online for easy access to better themselves in this field.

You don't have to be a Coach Mechanic to benefit from these sessions. I would definitely be taking full advantage of the free Webinars being offered by Motor Coach Industries.

Delco 38MT Starter Planetary Gear System

2009-07-22T17:50:00.000-07:00

Planetary Gear Systems have been around for awhile. A very common use for them are automatic transmissions. The gear ratios can be altered by changing which gear is driving and which gear is being driven. There is always one of these 3 gears that has to be fixed.
This Delco 38 MT starter pictured has been operating in a 2007 C2 School Bus. You can see the rust forming on the terminals. This is common since starters are placed low in the engine and close to the elements. We generally remove the starters on all our units every 2 years and give them a check over.

We lubricate the bearings/gears and check brushes plus wiring.
On this model the solenoid and relay switch(fastened to the side) are non-serviceable so they have to be replaced if there is any doubt on their mechanical condition.

Starters have come a long way and now most are using a gear reduction with more torque delivered for cranking over high compression diesel engines. The Delco 38MT on our Mercedes MBE 900 Diesel engines does the job even with it's light weight. These starters pack a punch and are light weight with mostly aluminum castings.

The planetary gear system in this starter has the typical sun gear (driven by the starter motor) the ring gear is fixed and part of the of the starter body, while the planet gears are part of the actual armature that delivers the starting drive to the engine ring gear.

This set up is extremely durable since there are 3 planetary gears to absorb the load and speed required. I've always been impressed by what a starter can do. It takes a lot just to crank over a diesel engine by hand and when you look at this medium sized starter it's really extraordinary especially when you consider the extra load required for cold starts.

The planetary gear system on this starter has a gear reduction of 3 1/2 : 1 ratio which slows down the output of the drive gear (3 1/2 revolutions of the starter motor to 1 revolution of the output drive gear). What this accomplishes is a high torque output that enables the smaller starter motor to punch out the turning force required to crank over the engine.

Here's a great explanation on planetary gears at "How Stuff Works"

This mechanic information will give you a basic understanding on new starter models that are in use today.

HOMEPAGE

Yamaha Bikes Going TurboDiesel!

2009-07-19T08:18:00.000-07:00

Source: hellforleathermagazine

I guess nothing is impossible and Yamaha has filed for a patent for a turbodiesel motorcycle engine. It will be an inline 4 with an intercooler and turbocharger added on which will place the fuel tank under the seat.

I would love to see the prototype once it comes out of the factory. Listening to a diesel engine in a street bike would tempt me to buy one. I love the knock of a diesel, coming from a much smaller vehicle would be surreal. The power and torque would be unbelievable with possibly a slow take off?

Who knows, with the much lighter chassis with a bike it might take off like a rocket. Check out the link above where you can view the patent information and some interesting ideas and concepts. This is very interesting providing mechanics information that you can bite your teeth into!

HOMEPAGE

New Technology - Laser Beams Replacing Spark Plugs.

2009-07-18T07:07:00.000-07:00

Laser Beam Ignition is Coming!

Here's some interesting news for Mechanics and Car Owners / Enthusiasts.

It's amazing what the future is going to bring us in the form of more efficient engines. It tells me that totally functional electric cars are coming but not right away since this laser research is costing a lot of money to develop.

Researchers in Liverpool are collaborating with Ford on developing this laser ignition system. The laser can be distributed strategically in a gas engine combustion chamber in key areas to achieve better combustion and fuel economy.

Cold weather starting will be much easier and efficient with this system. The laser will be hot enough to produce ignition with the air / fuel gas mixture. The laser can even send information back to the vehicle reporting on type of fuel, level of ignition and adjusts itself for more effective combustion.

The laser will have to fire 50 times per second to get 3000 rpm and will use much less power compared to a spark plug. I like this technology even though it still deals with fossil fuels, but emissions will be reduced drastically.

This laser system is working right now in the lab and will be implemented into higher end Ford vehicles.

Click HERE If you would like to read the entire article.

Does this technology sound familiar? Diesel engines use heat of compression to ignite the fuel. This laser beam system is using the same principle, although it would take much less heat to ignite a gas mixture compared to diesel fuel. This is another learning curve for dealership Mechanics at Ford more so than the rest of the world.

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Used School Bus For Sale

2009-07-16T00:43:00.000-07:00

Choosing a used bus for sale can be a difficult process if you don't know where to look. Ebay is by far the best resource for finding any kind of bus including used school buses. To locate a used school bus for sale follow the link below and you will be taken to Ebay, in my opinion the safest place to shop online.

Sellers have to be up front and honest with their selling practices because Ebay is watching. Every seller has a feedback rating that tells everybody how previous transactions went with past purchaser comments and ratings.

When looking for a used school bus for sale check out the sellers feedback. Have a look at the pictures provided and send off an email if you have a question for the seller. High mileage school buses doesn't mean they can't go another 100,000 miles depending on condition and what you plan on using it for.

Most used school buses are in very good condition since they were maintained under strict guidelines for obvious reasons, carrying school children everyday. The body rust could be an issue if the school bus came from a wet mountainous region that used a lot of road chemicals.

Gas or diesel engine?
My choice is always diesel since they can really take a licking with high mileage. Since most uses after the school fleet life of a bus is light duty, the life expectancy of a diesel will outweigh a gas engine. This all depends on the condition of the engine and how it was cared for.

The drivetrain is generally an automatic transmission. Allison transmissions are the most common. They are very durable and can go for many miles after retirement if cared for and maintained properly.

I have many posts here on my blog on common diesel engines and the Allison transmission found in school buses. They information is about failures and fixes along with maintenance tips. The search box in the top left hand corner will help you find what you are looking for.

Used Bus For Sale

California Cleaning Up School Bus Emissions on Diesel Engines

2009-07-15T07:00:00.001-07:00

California school districts in the southcoast area are doing a major clean up on diesel engine buses in 13 school districts at the cost of 43 million dollars. They are going to start runniing them on compressed natural gas and propane.

This measure was implemented by the Air Quality Management District. Approxamately 176 newer buses will get particulate trapping devices as well at a cost of 3 million dollars. I'm impressed with the seriousness of the California Gov't to clean up the air but the expense is unbelievable.

Read the full article HERE

Our fleet of 75 school buses come with diesel emission controlled engines that the factories have spent millions of dollars on already. The buses are equipped with particulate filters from factory and they do an excellent job. It will take a long time to change over to Propane and natural gas due to the expense.

New Study Heavy Duty Diesel Emissions Reduced Drastically-New York Times

2009-07-12T13:12:00.000-07:00

I'm Guessing The Next Study Will Be Lowering Emissions On Super Duty Diesels like the one ABOVE!

Here's an interesting article on a 5 year study by several Environmental Groups including the Health Effects Institute, Coordinating Research Council, Energy Dept., EPA, Engine Manufacturers Association and the American Petroleum Institute.

Read The Full Article HERE

Researchers have found particulate matter called soot has been reduced by 99% from levels allowed in 2004. Emissions are also 90% lower than 2007 standard requirements. Good news for us and the air that keeps us alive!

Right now the new DPF (diesel particulate filter) mufflers are collecting soot and burning it off into the atmosphere automatically by way of computer technology. The DPF has sensors that tell the computer the temperature is getting excessive on one end and needs to start a regeneration.

Regeneration is computer activated which injects atomized diesel into the exhaust system burning off accumulated soot. If the soot buildup gets too much to handle, a manual regeneration is required using laptop software.

This manual regeneration takes about 45 minutes and the temperatures get at high as 1200 degrees. This is a very efficient way to burn off particulates/soot. Every Mechanic involved with today's diesel engines will be repairing and maintaining these emission controlled systems for many years to come.

Cat 3116 Troubleshooting No Power

2009-07-09T21:56:00.000-07:00

The problem with this 3116 Cat Diesel Engine was no power. The funny thing was it felt like someone stuck a banana in the tailpipe. There was no engine miss or hesitation what so ever. I checked for excessive back-pressure and that was normal.

One thing that seemed curious was the rpms in neutral went to the maximum without any problem but as soon as you put a load on the engine the rpms stayed at around 1200 rpm with no torque at all.

The Cat 3116 Governor controls the fuel rack which in turn decides how much fuel to allow to the injectors according to engine load and speed. The operator controls the throttle and the load is read off of the turbo boost pressure. The boost line goes directly to the governor air fuel ratio control. The more boost, the governor moves the rack for more fuel.

I tested the air/fuel ratio diaphragm with a regulator on the bus and it was leaking into the housing meaning the diaphragm had failed. Once I replaced the diaphragm it was a no-brainer to retest the new assembly and check for leaks. The new diaphragm was holding nicely.

NOTE: Don't test diaphragm over 20 psi

Here is a picture of the old diaphragm with a split in it. I remember the red flag that popped into my head when I called the Cat dealer for this part and they had 3 diaphragms on the shelf. Perhaps a recurring problem?

The 3 allen head screws are removed to pull the cover off to replace the diaphragm. This is an easy procedure once the governor is removed from the engine.

The governor linkage must be unhooked from the fuel rack before removing. Here you can see the pin which slides into the linkage and secured with a C clip.

The governor does not have to be timed and is fastened to the engine with 3 m8 bolts. Not much to it once all the fuel lines and piping is removed. This was a case of a smooth No Power situation. There was no white or black smoke, the engine did not miss or do anything really obvious. Testing the diaphragm with the air regulator is just another way for a diesel mechanic to troubleshoot a Cat 3116 Diesel Engine.

Delco Remy Starter - Troubleshooting Noisy Engagement

2009-07-04T22:32:00.000-07:00

Usually when a starter is noisy during engagement you will have to remove it and check it over. Other things to check is the flywheel teeth that mesh with the starter drive gear. When the starter continually spins at high speed while starting then either the drive gear or the flywheel teeth are badly worn. What causes this is the operator engaging the starter while the engine is running. The starter below has a worn groove where the snap ring is positioned.

The machined groove should be as thick as the lock ring. You can see the groove has been worn lengthwise from the constant pounding of the drive gear during normal starting. The lock ring fits inside the washer on the shaft and locks the two together to provide a stopping point for the drive gear when the starter is engaged.

The only way to repair this condition is replacing the starter or the armature shaft. Either way the shaft itself cannot be repaired. The Mechanic has to decide which route to take in this situation.

Spring Brakes - New Long Stroke Models

2009-06-28T10:08:00.000-07:00

Spring Brakes are the safest (since the new design) and most powerful parking brake mechanism available for highway & industrial trucks and equipment. The spring itself could knock a whole in the wall if unleashed from the spring brake chamber.

Years ago there used to be a removable clamp on the spring brake section so the diaphragm could be replaced. This was soon changed to a permanent solid clamp because of the numerous accidents and deaths that occurred from inexperienced people unclamping the spring assembly. without spring brake tool for caging the spring.

The spring brake tool or Caging Bolt as it's called comes with every spring brake chamber and must be left on in case the time arises for spring brake caging. This tool hooks on to the spring inside the brake chamber. The tool is inserted and turned too the right in a "T" shaped orifice then screwed tight on the outside of the pot with a 3/4 inch wrench.

Today spring brakes come in a Long Stroke version that allows more travel and less chance of going over the slack adjuster travel limits. The Long Stroke has 1/2 inch more travel at 2.5 inches maximum. The total stroke is 3.0 inches which is strictly to allow extra movement if the 2.5 inch stroke is reached.

Every Long Stroke spring brake chamber comes with square threaded fitting ports and a stamping and/or tag attached to the brake chamber body. The body itself is much longer than the original 30 Series brake chambers. Every Mechanic and operator should know the limits of these and other spring brake models.

Spring Brakes are the most important part of any highway vehicle operating on the road today.

Troubleshooting Electronic Diesel Engines

2009-06-16T06:22:00.000-07:00

Troubleshooting electronic diesel engines can be a headache if you don't have the troubleshooting software required to check for codes. This is the first step when there is a amber or red code indicator light on the dash.

Once you rertrieve the code you can get a general idea what part of the electronic system to start focusing on. It may be a lost signal from a sensor or an innacurate signal that the computer (ECM) picked up.

Computers being as logical as they are will pick up on anything that is not within parameters according to the way they were programmed. This is a grreat advantage to your troubleshooting process.

Don't rule out the basics. A poor connection causing resistance will fool the ECM on the amount of resistance or voltage a sensor relays back to home. Always check connections both positive and ground starting at the battery.

There have been several instances in my shop where a poor ground has been the root of many electrical problems especially with electronic systems. So the first step is to check the electrical source thoroughly and then hook up the laptop.

If you send me a question about an electronic diesel engine with a code on the dash, I will tell you to follow the sequence in the above paragraph. It's reality now, every shop running or servicing electronic diesel engines need to have the proper software to get by with day to day operations.

How To Troubleshoot Air Brake System ABS Code .

2009-05-26T22:47:00.000-07:00

This ABS system is by Meritor Wabco found on most highway transport vehicles. An ABS light on the dash indicates a problem that has to be repaired since an ABS fault is a fail according to Motor Vehicle Inspection criteria. The ABS system does not operate normally when there is an active code.

The code description reads "Right Front Wheel Sensor - Open"

When looking at the Right Front wheel the sensor looks like it's intact. The first thing to check is to make sure the sensor is pushed all the way into the housing. The sensor reads a tone wheel on the hub and sends a signal to the ABS Control Module.

According to the troubleshooting specs the resistance of the sensor should be between 900 and 2000 ohms. When I checked it out there was no continuity causing an obvious open circuit as indicated by the fault description. The first step is to check the wiring itself for any damage or the possibility of a faulty sensor. Most times exposed wiring to the environment is at fault when troubleshooting a circuit problem.

Further inspection shows a spot on the sensor wiring that has rubbed through on the brake pot assembly. One of 2 wires has been damaged and caused the open circuit condition. I use heat shrink butt splices since they seal very nicely from the environment.

Once the wiring was repaired I moved the bus in a forward direction & the ABS warning light went out. This was an easy fix and it was nice to stumble across the bad wire in an easy to reach location. This conventional school bus is a only a year old but you never know what can happen to wiring and components when operating on a daily basis. I hope this mechanic information has helped you out and maybe you will have it as easy as I did with repairing this failure.

School Bus Power Steering Pump Front Seal

2009-05-21T07:54:00.001-07:00

This is a Haldex 2 stage Power Steering Pump removed from one of our 1998 Pusher School Buses. The problem found was the power steering level was rising on it's own. No, it's not magic but a front seal allowing engine oil to enter the pump suction side.

The power steering pump is bolted in tandem to the rear of the air compressor which has an open crankcase with lots of engine oil being splashed about. Since the suction side of the pump is facing in this direction, if the seal is faulty engine oil will enter the pump and end up in the power steering reservoir.

One quick check to confirm this is the engine oil is black as usual from hydrocarbons while P.S. oil is standard 10w30 engine oil so there is a noticeable difference from the normal appearance.
To change the seal the pump must be removed and the front housing taken off. Always mark the pump stages before dis-assembly for easy reassembly.

With the end housing taken off the seal snap ring can be removed then the front seal can be easily replaced. This pump operates not only the power steering but the hydraulic fan motor as well. There are 2 output ports on the pump which supply pressure oil to run the 2 systems. This pump is mainly found on the 3116 cat Engines in our fleet & work very well in normal day to day operations.

Mechanic Troubleshooting - Allison Transmission Wiring

2009-05-17T12:34:00.000-07:00

Our fleet has absolutely zero manual transmissions, school bus drive trains are unless requested differently come standard with Allison MD 3000 electronic transmissions. Once they get a few years use there are electrical glitches that occur.

In this case the code pointed to the C3 pressure switch. This switch reads the clutch pack #3 oil pressure in the transmission module. It activates at around 37 psi when pressure is operating the clutch release and engagement.

If it fails, a code 32 will pop up. Most times the wiring is at fault so we will check the continuity from the ECU to the Trans. Module. (shown in the photo above)
At the front end the blue connector has to be disconnected from the ECU where the appropriate terminals have to be probed and checked for resistance. The Allison troubleshooting manual is a "must have" for this procedure. For newer units the WTEC 3 is required(world transmissions electronic controls). These manuals are available at an Allison dealer.

You can tell if the system is in the 3rd generation from the 3 connectors at the ECU. In this case the ECU is located under the driver side floorboard attached to the body(Thomas 1999 Saf-t-liner).

The resistance read 25 ohms which is excessive. As with other codes replacing wiring has become a common occurrence. We use shielded wiring which we run front to back to eliminate the defective wire. Many times if transmissions act up and shift awkwardly in wet weather there's a good chance you have a wiring issue.

How To Manually Check for Transmission Codes

Press the 2 arrows on the shift pad with key on and read the 4 digit code that comes up. Record the first 4 number code then press mode which will bring up a second code(if any) . I hope this mechanic information has helped you out.

Replacing Power Steering Hoses on a pusher school bus

2009-05-10T07:59:00.000-07:00

Replacing power steering hoses on a pusher school bus involves bypassing the original steel power steering lines. This school bus is almost 12 years old, the pipes deteriorate over time from rust and vibration. They are clamped to the underside and usually start to leak in that area.

To make the job quicker we replace the pressure and return lines with high pressure double wire braided hoses. The ends are pipe thread and can be easily adapted to fit properly. The factory piping needs to be flushed out after and plugged since it will drip oil for days after and appear to look like the power steering is still leaking.

The hoist makes this job much easier running the new lines and securing them to the body. Once the lines are installed, the filters in the reservoir should be changed and 10w30 engine oil added. We found on occasion that 15w40 is too heavy an oil and creates a backup in the reservoir causing seepage.

The hoses are approximately 40 feet long and can be made up at a hose shop. They have all the tools that a mechanic shop could not justify to have since this is not a regular failure. This mechanic fix isn't hard to diagnose since oil leaks are pretty obvious to the naked eye.

Diesel Engine Cranks Does Not Start

2009-04-30T06:36:00.000-07:00

If a diesel engine cranks but does not start the first thing you want to look at is the power feed to the engine controls. In this case it's a Mercedes mbe 900 diesel engine in a 2007 conventional school bus. The first check is the fuse block since this powers up the ignition relays that operate the engine control modules.

Here is the Engine Power Distribution Module (photo below) with the relay that sends a signal to the engine control module.
The wavy line on circuit here has a ground to one side. With no ground the coil does not energize which will not allow the circuit to close.

Mercedes diesel engines have 2 modules, one on the engine and the other inside the cab. The ignition switch activates the relays that gives us the start operation. We found voltage to the cab module but when the engine was cranked over there was a voltage drop down to '0' Volts.

Tracing the wires and checking for continuity was the first step since a voltage drop means a resistance problem in one of the circuits. With the help of the Thomas Bus Tech Line we found the circuits to both relays then found the ground to be non-existent for both ignition relays.
These 2 ground wires (photo below) energize the coils within the relays. No grounds of course caused these relays to be become inactive.
After running a temporary ground the engine started. So obviously we had to check the ground connections on the firewall and the frame. After some digging there was a broken connector to a frame ground below the cab. Once repaired, the engine was back to normal once again.
The photo below shows the broken ground cable found just below the cab firewall on the outside of the frame rail.

This is Mechanical information that points out that a bad ground can cause a lot of electrical problems and should always be checked first starting at the batteries. A digital volt meter will tell you a lot with voltage and resistance readings. The higher the resistance the lower the amperage.

Cat 3116 Oil Cooler Repair

2009-04-22T21:43:00.000-07:00

This Cat 3116 oil cooler was leaking oil so disassembly was required. On a Thomas Saf-t-liner school bus the complete air cleaner and piping can be removed to gain better access to the cooler and turbocharger. The turbo must be removed to get at all the fasteners on the cooler assy. Before removing the cooler parts the coolant must be drained from the block or radiator. There is a block drain (hex head) at the right rear of the engine behind the turbo.
Above you can see the oil cooler parts. The outer housing and the cooler itself are seperated by 2 gaskets which have hardened over time and became brittle.
Using guide bolts slide the first gasket and then the cooler bundle over the guide bolts. There are also to o-ring seals located at the bottom of the cooler.
Once the outer housing is installed the m8 bolts are installed and torqued to 20 ft. lbs. This isn't a major job but it still takes time and patience to get to the cooler. We have 13 Cat 3116 engines and the oil coolers have never failed as far as leaking oil into the cooling system.

Replacing Worn Alternator Pulley Serpentine Belt

2009-04-11T20:30:00.000-07:00

These are typical pulleys that run a serpentine belt on a Leece Neville alternator. The alternator pulley on the right is the original and is worn on the top edges of the pulley grooves. They are flattened out from belt wear which tells you how durable today's serpentine belts can be.

Of course we launced a campaign to replace the pulleys on the other buses spec'd with the same alternator. Click on the picture above for a closer look (if you could hold these pulleys in your hands you would see the wear much clearer)

The alternator puts out 160 amps so there will be a substantial load on the pulleys and the belt. The engine is a Cummins ISC which uses a tensioner pulley. If this pulley was left on any longer there very well could have been belt slippage eventually. Most mechanics (myself included) would not notice this wear especially during an alternator replacement.

We looked a little closer in this case because of a recurring charging system problem. That's what happens when you look a little deeper into a stubborn mechanical problem.

Cummins Diesel Repair - ISC Model

2009-04-06T22:48:00.000-07:00

This particular Cummins diesel repair was necessary because of an indirect code that was finally traced to the camshaft endplay. There are 2 sensors installed to the backside of the timing cover just below the top drive gear (the 2 black round shaped sensors are visible to the right of the cam shaft bearing bore). One is the camshaft position sensor the other is the engine speed sensor.

The camshaft has been removed as well as the cam gear (above). You can see the tone wheel that the sensors read and send a voltage signal to the engine ECU. When there is a problem with these readings an engine code appears and a driveability problem arises. There is a specified air gap between the cam gear and sensors, if that gap is not maintained an inaccurate signal is produced. This is typical for most electronic diesel engines and care has to be taken when handling these components.
To remove the camshaft the rocker arms and shafts must be removed first. The wooden dowels act as holding devices that jam into the solid lifters that ride on top of the cam lobes. Once the dowels are installed elastic bands are used to hold them secure while removing the camshaft. This saves a lot of time not having to pull the cylinder head.

The camshaft endplay was excessive which caused the sensor problem/codes to become a regular occurrence. The first step we took was to change the sensors, this cured the problem for several weeks but the fault always came back to haunt us. The camshaft showed signs of wear on the shoulder where the gear sits and the cam lobes as well. There is a thrust washer that goes between the gear and the engine block to help with endplay movement.

If you have to do this job in a Thomas ER Pusher Bus you will have to remove the rear engine mounts and lower the engine enough to get the rear pushrods out of the engine. The solid floorboards above are not designed to allow the pushrods enough headroom for removal.

The cam gear has to be heated to 400 degrees Fahrenheit to install back onto the camshaft. We elected to replace the gear as well as the camshaft. If you are a Diesel Mechanic this is a Cummins Engine repair you may have to go through one day. I hope this mechanic info has helped you understand the procedures involved in this operation.

Cummins Diesel Engine Drive Gears

2009-03-25T22:40:00.000-07:00

If you were to remove the front cover off of any diesel engine you will come across a series of drive gears. No belts or chains here, you're looking at the timing gears that make this diesel engine run. Each gear is timed to each other with specially placed marks that must be lined up during assembly.

Enlarge this picture by clicking on it and you should see the timing marks on the crank and cam gears. They look like center punch marks one on the crank and two marks on the camshaft.

The crankshaft and camshaft gears are driven together to provide proper valve and piston timing for combustion to occur. Fuel injection timing on the Cummins C Model diesel engine (pictured here) is accomplished by inserting a pin into the injection pump drive gear (top right).

The pump in turn has a pin in the side of it's housing that has to be removed, flipped around & aligned into the injection pump shaft setting it for injection on #1 cylinder.

The oil pump is also driven off of the crank gear and idler gear. The air compressor is located lower right without it's drive gear installed.

The Benefits of Diesel Mechanic Colleges .

2009-03-17T23:30:00.000-07:00

Back in 1977 I entered Diesel Mechanic School at the local college. This was the start of my 4 year apprenticeship as a Heavy Duty Mechanic. This first step was called a pre-apprenticeship which would last 6 months. I had never touched a diesel engine before and had some automotive/small engine experience from high school.

There was also other areas that would be covered such as gas engines, electrical components, hydraulics, air brakes & drive trains. I really enjoyed all this technical stuff even though it was information overload.

Obtaining diesel mechanic info was my primary objective as well as experiencing hands on maintenance and repairs. With the aid of pictures, videos and books my first taste of college was very positive.
Learning about tools and how to use them including dial indicators, micrometers and other specialty tools was a huge asset. When you hit the pavement with your resume you need to know the language. Diesel Mechanic pay these days depends on your experience and where you live. This trade is very diverse; mining, highway trucks, earth moving equipment and fuel injection are some of the specialized fields that you can choose from.

A Video Says A Thousand Words!

Once you get some experience under your belt you will be looking for more challenges and honing your troubleshooting skills. I like working out in the field as a mobile diesel mechanic because you don't know exactly what's in store for you when you get to the problem.

If you're interested in getting into this trade I would go down to the nearest diesel mechanic college or technical school and ask some questions about the curriculum and cost. You usually have to buy your own books which can add up fast but they will pay you back ten fold with new found knowledge. I'm content now after working in this trade for 32 years and find myself telling a lot of stories about experiences and aha moments & wouldn't trade it for the world!