Monday, April 30, 2012

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.


Bruce H Fader said...

Sorry, didn't know where I could put this:

Here is what it was doing.

It quit outside of Kersley and wouldn't start normally. I used a spray into the airfilter and she got going again. I turned it off again at Boston Bar to check the oil and again she wouldn't start. Sprayed her and she got going.

Around Langley the real problems started. She stalled when I hit the brake and reduced speed to 80 km. Just dead. No warning stutters, or hitches, or anything. Almost got rear ended by a semi in the process. Pulled her over and started her again with the spray; no problem. Got her going and managed to limp into Vancouver and park her where I am staying on east 1st avenue.

Went to go get a new fuel filter, because I figured that might be the problem, but she wouldn't start, with the spray, or otherwise. Missed getting the fuel filter and tried to clean the one in there, but it still wouldn't work.

Checked the bleeder valve at the fuel filter and turned the key; fuel came out, so the pump is fine. Checked the one near the fuel injector pump and nothing. Replaced the fuel filter, but she still won't work, but am now getting fuel at the injector bleeder valve. Getting some puffs of smoke out the tailpipe, but she isn't catching. Been a couple of horrendous clanks, but they come and go.

I think, in light of the fact that she isn't firing even with the spray, that some of the glow plugs are damaged. Only two of the eight are fairly new and both of those are on the driver side. I suspect that the glow plugs on the passenger side are as old as the truck; so 20 years old.

John Whelan said...

Bruce, I don't know your engine model but it may be air in your fuel or bad injectors? If 'ether' is the only way to get it going then there isn't enough fuel or poor atomization from poor injection.

les klusack said...

I hope you will answer my question I have a 1986 blue bird diesel I am turning it into an RV My question is...can I remove the heater on the drivers side at the middle of the bus including the duct work all the way up to the drivers seat

John Whelan said...

Yes you can if it doesn't leave gaping holes in the body.

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