Mechanic School Bus Pusher Model Overview

Mechanic Notes: working on school bus pushers.
The Bus Mechanic has a different approach compared to working on a pusher school bus since the drive  train is reversed at the back end. The controls are hard wired to a major junction box in the rear engine compartment. They have a single drive axle (1998 model pictured here) with a stubby driveshaft which eliminates a 30 foot driveline. That's one advantage to this design along with a very low noise level for the operator.

Since all the weight is on the rear axle another obvious advantage is the great traction and handling, especially in the winter. The multiple leaf spring pack provides a solid ride but without the hard knocks of a forward chassis model. Having one drive axle compared to a Class 8 tandem makes life easier when it comes to axle work. With just one axle the brake shoes are a special size at 8 5/8 inch wide with 16 1/2 inch brake drums.







The rear engine design has it's pros and cons. The front end is a real treat to work on as you can see here. however you  need to lay over the top of the engine for valve sets or head removal. The transverse fan is common in ER models which use a hydraulic drive fan motor but in this MVP Thomas pusher with a CAT 3126 the fan drive is belt driven.

As a Mechanic you will have new and exciting challenges in whatever piece of equipment you work on and in time you will always find easier ways to work around problems and get to know the symptoms / solutions as time goes on.

A Mechanic On Mechanics

My Mechanic's Thoughts On The Field Of Mechanics
I never thought that I'd be sitting here blogging about the mechanic's trade 35 years after getting into a Heavy Duty Mechanic Pre-Apprenticeship Course. Back then Heavy Duty Mechanics was an all around trade which involved all heavy equipment including class eight trucks, earth moving equipment and automotive vehicles.

Years later Commercial Transport serving the transport truck field came on board and HD Mechanics became an earth moving / Mining equipment trade. It was information overload back then with all this equipment combined into a 6 month course. No complaints,  it was a welcome handful of knowledge.

Realistically you wouldn't be able to hop around from a truck shop to a Mining site too easily because of the diversity in each industry. working on a P&H shovel is totally different compared to a Class 8 highway truck. I worked for Highland Valley Copper in Logan Lake for a few months (between jobs) and it was policy for new mechanics to start with the Shovel and Drill crew. I had copper mining experience during my apprenticeship but I felt like a newborn climbing up a drill mast on a graveyard shift.

The Mechanic trade is full of new experiences and I have stories I can tell, some are strange and quirky. For example:The GM diesel engine that ran backwards one day and the heat riser valve that trickled down to block the muffler causing grief and embarrassment (ate some hours on that one). But.....If you are human you WILL error.

I had a very nasty Journeyman during my second year apprenticeship and he had minimal time to teach me anything and thought apprentices were a waste of skin. Unfortunate but luckily he was the only low point of my career and until I became certified I had the pleasure of working with very honorable Journeyman.

I couldn't wait to become a Journeyman and teach others, it's rewarding to help others. You look at rich and powerful people who are avid philanthropists who state that giving back is the most satisfying gesture of all. It doesn't have to be cash or cars but sharing your knowledge is priceless.

 I still remember things I was taught that are still with me to this day so keep it in mind when someone asks you a question :)




Remember To Think Safety On The Job...Don't try this at home. These guys in the video below are testing out an air bag. After too many beers.....

School Transportation News

School Transportation News - Overview

In my opinion School Transportation News is the most up to date school transportation magazine that's available both online and offline. They publish 11 months out of the year and clearly have their finger on the pulse of the school bus transportation industry.

 



















They are a great source for what's happening in the industry along with trends that affect the safety and efficiency of school bus transportation throughout North America. School Transportation News is viewed by over 23,000 people working in the industry along with agencies from all levels of government and national associations.

STN is always looking for the latest news and stories related to school bus transportation to keep the magazine current. Below are some highlights that I recommend from their website.

They have a Resources Page with maintenance tips, repairs and specifications.

Hundreds of articles: My personal favorite the School Bus Bay section.

Also a social media section called STN SOCIAL where school bus mechanics and anyone interested can hang out, interact, ask questions and publish new found solutions to a problem.

 Since School Transportation News comes in a Digital Version you have online access to everything and anything school bus related. I recommend taking some time to check it out!

Cat 3126 Hard Starting & Running Rough

The CAT 3126 Diesel Engine uses electronic fuel injection and they use HEUI (Hydraulically actuated, Electronically controlled Unit Injector) which require high pressure engine oil to actuate injection. The high pressure oil pump is mounted on the driver side and is engine driven. The hard part of this problem regarding our fleet is we do not have any CAT 3126 software to troubleshoot this problem.

So as with DT466 electronic engines the most common failures is the o-ring seals on the injectors. If high pressure oil is bypassing, the injection cycle is incomplete and the hard start poor running condition develops.

Side Note:  By varying the oil pressure, injection can be controlled independently of the position or speed of the engine crankshaft or camshaft. The injectors are controlled by a Powertrain Control Module or PCM. Injection Pressures can reach as high as 18,000 to 24,000 PSI.

Since this particular engine has accumulated lots of  miles without having a major tune-up besides a valve set we pulled all of the injectors and found the problem. The o-rings failed on a couple of the injectors enough to cause a constant problem every day cranking over the engine excessively to get it started and having a bad miss when warm.

Cat Engines specify that you need a Cat tool specifically designed to install these injectors, well since we only have a few of these engines in our fleet (and want to save money on tools) we found another way to push the injectors into the bore.

Use an appropriate sized combination wrench to gain leverage using the open end, coat the o-rings with clean engine oil and seat the injector using the injector hold down or body casting. (whatever you use take care and push the injector into the bore without force making sure it goes into the bore evenly). using the hold down bolt to install the injector is not advised but you can lightly snug it up as you progress.

The main point here is to not pry on the very top of the injector where the solenoid is located.We found this technique in our International installation manual. The HEUI injectors are used in their engines as well.

I hope this information helps you out the next time you have a CAT 3126 Diesel Engine with a hard start or rough run condition.

Cummins 5.9 Diesel Fuel in Oil

Replacing Injectors Cummins 5.9 Diesel Engine

Here is a question I received from one of my subscribers and since it's a common problem with the Cummins 5.9 diesel engines I wanted to post it and share it. This applies to the 2004.5 - 2007 year engines.

Question: I have been working on a cummins power generator engine Model 6 BT 5.9 G1 for some time now. The problem was with fuel leaking into the oil sump. I was gonna over haul the engine but prior to that i would like you to suggest the problems related to this. Can you please advice me on the common problems which will cause the fuel to leak into the engine sump.

Answer: Leaking injectors is the most common problem with a fuel collecting in the oil pan. If you're finding your oil level is rising this may be the problem. I usually put new fuel connecting tubes with new injectors (the Mechanic in the video calls them feed tubes). The feed tubes are indexed so you can't go wrong when lining them up with the injectors during installation. The Mechanic in the video explains in detail and makes this operation a snap.




This second video is from another Mechanic who demonstrates some important techniques when removing and installing Cummins 5.9 injectors. I love these videos because of the no frills production from technicians who have a good foothold and knowledge with this type of repair.  NOTE: Torquing everything demonstrated here to specs is extremely important.

 NOTE: Here's a  post with a link to a 15 page manual on tools required, procedures and torque specs compliments of a  Dodge Diesel Forum  member. Thanks Boys!

How To Become A Professional Automotive Technician

Professional Automotive Technician Advice.... from Eric The Car Guy.

 Listen to Eric explain important details on becoming an Auto Technician including ASE certification. He speaks very candidly and fills in all the answers that you're looking for. The main point he makes is "go to a tech school!". I like his statement on finding a shop that will provide upgrading and help you advance in the trade. Check out the video if you're thinking about the automotive technician trade or ready to go full throttle, you'll find some great insight from an experienced mechanic who has been through it already.

How Diesel Engine Turbochargers Work

How Diesel Engine Turbochargers Work

Mechanic Notes:  A diesel engine is 'dead in the water' without the turbocharger. High pressure atomized diesel injection needs maximum air intake boost to operate efficiently. You'll know when the turbo is not working up to speed, the smoke show out the tail pipe will be the obvious sign.

 Mechanic Checks for A Turbocharger Problem
If you suspect a turbocharger problem and the diesel engine you're working on is a mechanical model you can check the boost pressure which should be around 20 p.s.i.

Take the reading off of the intake manifold with the engine at full throttle and full load. Hook up a line and go for a road test and make sure you get a nice heavy pull on the engine. The next step is to remove the intake side of the turbo (easier than the exhaust side) and check the compressor wheel and shaft for any movement and wear or signs of engine oil in the piping.

The air induction system includes the air filter and piping which must not be overlooked. Simple steps include checking for a restriction in the air filter and visually checking out the piping for loose clamps and perforations. The first sign of a hole in the piping or a loose clamp will be a high pitched whistle, not to be confused with the characteristic whine that comes from a turbocharger under load.

 This is a common problem and can be checked by setting the park brake (set wheel chocks as an extra precaution), foot brake on, transmission in gear and throttling up the engine RPM enough to feel a load. You'll need assistance with this test so you can look and feel for leaks.

Electronically controlled diesel engines will most likely flash a trouble code on the dash which requires diagnosis with a laptop / software. The modern day Mechanic needs software and a laptop...if you don't have these tools you're going to go down fighting.

Here's an excellent video tutorial on how the turbocharger works. Check it out!

Cummins 24 Valve Turbo Diesel Torquing Head bolts

Torquing Head Bolts on a Cummins 24 Valve Turbo Diesel Engine.
This is a video I posted years ago on Youtube. There was a lot of noise in the background and I just grabbed my torque wrench and went through the sequence. I apologize for the poor video quality but I get my point across :)

The Torque Pattern
Start from the middle of the head in a circular pattern outwards. Torque to 59 ft.lbs then 77 ft. lbs. check again at 77 ft.lbs. then finally another 90 degrees. Coat threads lightly with engine oil. This is a universal torque pattern that makes sense to apply to any type of diesel or gas engine.

Starting from the middle and moving outwards so the head is fastened down evenly. Cummins uses a system called torque and turn which accounts for the extra 90 degrees to finish off. The Cummins 24 valve turbo diesel (5.9 Liter or 359 cubic inches) is one of the most dependable engines in our fleet.

 I must add that this diesel is an electronic model known as the ISB which stands for Interact System B.

Below are some extra Specs:
- Fuel System = Direct Injection
- 1998.5 - 2002: Electronically controlled Bosch VP44 rotary injection pump.
- 2003-2007: Bosch high pressure common rail injection.
- 235 - 325 HP @ 2,900 RPM
-  460 - 610 lb-ft @ 1,600 RPM

 



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Mechanic Careers And How You Can Succeed

Mechanic Careers - How to Succeed & Decide If It's Right For Your Future.

Yes it's true that Mechanic Careers are abundant around the world but getting started is the hard part. You may have a background in the trade which is a bonus. You need to be good with tools and have a certain level of aptitude that gives you the upper hand when assessing each job you receive. Taking a pre-apprenticeship course is a wise investment.

There are thousands of colleges and technical institutes that offer 6 to 10 month courses. The main focus is to learn the basics, why? If you are interviewing with a prospective employer they will smell a rookie from a mile away. Not knowing basic terms and technological lingo will prevent you from selling yourself.

A Mechanic pre-apprenticeship course instructs you on everything from nuts and bolts to tools and the all important theory you need to become confident when you apply for a job.

Successful Mechanics Possess A Great Attitude Attitude Attitude

I've worked with fellow Mechanics (not many) that had bad attitudes. The terms "good enough" or "let's just patch it up and kick it out the door". Your signature needs to be on every job you do. Working in retail will subject you to different personalities.

If you show that you care even the nastiest customer will bow to your compassion and understanding. Think about it...would you rather spend money on a kick butt vacation or pay  $400.00 on a fuel pump on your 10 year old car that's ready for a trade-in?

Most people aren't in the best of moods when they have to open up their wallet. That's why I say attitude is a huge factor when an employer is ready to hire. I believe it's much easier to train someone with a positive attitude compared to the opposite mindset.

Mechanic Careers - My Big Break!

To Succeed with a Mechanic Career all you need is knowledge and the right mindset to catch an employer's eye. The more you apply the odds get better, don't limit yourself to your hometown. I went north as a young man (sounds familiar?) as a total greenhorn.

With a 6 month pre-app and maybe a year of experience in mining I pulled up anchor and worked up North, a 12 hour drive and if I had not taken the challenge to work in a customer truck shop my Mechanic Career would have been extremely limited.

So go for it! get schooled, get out of your comfort zone.... be ready to uproot yourself and start your career with a passion!!

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DT 466 Fuel Inlet Restriction Test

DT 466 Diesel Engine Fuel Inlet Restriction Test -  Robert Bosch MW / A injection pumps.

Another DT 466 engine diagnostic test procedure that you can carry out easily is a fuel inlet restriction test.  This will tell you if you have a restriction  between the fuel tank and the suction side of the pump.

The causes of a restriction may be a kinked or pinched fuel line or a blockage in the fuel suction line in the tank. The tools required is a tee fitting and a vacuum guage with a 0-15 In. Hg. between the outlet of the Primary fuel filter and the suction side of the injection pump transfer pump.

DT 466 Fuel Restriction Test Procedure

Run the engine at high idle no load and measure the restriction. If it exceeds 6 in. hg. there is an excessive restriction and it has to be located and repaired. most times the fuel line can be at fault or something foreign entered the fuel tank blocking fuel flow.

The mechanical DT 466 diesel engine may be long in the tooth now but for an owner / operator / Mechanic who is handy with a wrench these models are easy to work on.

If you're wondering what diesel engine I would recommend for P&D, farming, construction whatever....the International DT 466 is golden in my book.