Tuesday, September 20, 2011

Mechanic Tips-School Bus Fleet Preventive Maintenance

Every Fleet Mechanic will have there own ideas on how to set up the best PM program for their equipment which will vary for different locations. With different climates, road conditions and power trains the procedures will never be exactly the same. Our shop likes to condense the annual PM since the regular checks are carried out every 5000 Kilometers (3000 Miles). Oil changes are done every 15,000 Km with an oil sample to be analyzed. Fuel filters are replaced at every oil change.

The Allison 2000 and 3000 Transmissions  are all running on TES-295 Synthetic oil which has drastically cut down on repairs. Right now we change the oil every 3 years, the newer buses have prognostics which tells us with a dash light indicator when the filter and oil needs to be changed. Air filters are replaced every year regardless of the mileage. Steering Filters are serviced along with changing the oil every 2 years. Valve Sets are carried out according to the Manufacturer i.e Cummins every 5000 Hours or 240,000 Km (Electronic Models). With the introduction to emission controls in 2007 we now have to perform manual regens if required and replace the DPF (diesel particulate filter) every 150,000 Km (90,000 Miles)

Air Dryers every 2 years with a new unloader kit and dessicant filter. Dirt is a factor on school buses so we service interior heater filters and the entire lighting system (Non-LED lights). We check the starting and charging systems including the battery pack. If necessary we will run tests on the batteries and alternator. years ago alternators and starters were removed for rebuild but the time and parts did not add up as an economic strategy so we decided to give these components a 5 year life span before determining if they would need replacement. The cost has come down so much on electrical reman units, it's feasible to go this route with the added bonus of a warranty period.
Spring brake chambers are replaced every 5 years regardless of mileage and condition. The Mercedes MBE 900 requires a coolant and thermostat change every 2 years, the other diesel engines in our fleet do not have a time or mileage limit but we're working on that to prevent antifreeze deterioration and thermostat failures. Our tires tread depth is measured every Summer and pressures checked during each service.

Common sense plays a role with any preventive maintenance program and we found the best way to set one up is to sit all the Mechanics down in one room and go through the fleet  figuring out the best program to cover all the bases. Breakdowns will quickly eat up your labor time and parts budget like wildfire so keeping on top of maintenance with a feasible program will pay you back 10 times over.                                                                     


george said...

Hi John: I just started reading your posts and and the sharing of information you are providing is very interesting. I came across an older post of the cat 3116 top end set up, was unable to see the videos you provided and was wondering if you could help me see them as I am in the midst of one right now and would like to see the correct procedure. Thanx in advance for any help ypu can ptovide. geo.

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Karz.Biz said...

Do you believe I could do the job of school bus mechanic if I have been an auto tech professionally for 18+ years, worked on military trucks for 15 years?

Karz.Biz said...

could I repair school busses with 18+ years as ASE certified auto mechanic No diesel exp.
15 years as Army wheel vehicle truck mechanic. Mostly diesel but never actually worked on the engine to much extent?

J. E. Whelan said...

Do search top left hand corner for Cat 3116 and you should get all the posts. Leave another comment if you can't find the videos and I will help you out.

J. E. Whelan said...

Of course you could be a school bus mechanic, you have the experience. All you need is aptitude, tools and a good manual.

Darrin said...

Hi John, I was wondering if you could help me out. I just recently purchased a 1998 International with a DT 530 in it. When driving it home yeasterday, the oil pressure suddenly dropped to 0 psi on the gauge, and the warning light and buzzer came on. I quickly pulled over and shut it down to see what the problem could be, and nothing appeared to be wrong - no leaks, plenty of oil, etc. I started it back up and it ran fine, but still no oil pressure. My friend was following me from behind in another car, and we both decided that if it had run this long without oil pressure and hedn't blown up, perhaps it was the oil pressure sending unit that has given up on it? I was under the inpresion that an HEUI injected engine wouldn't run without oil pressure. Do you think it would be the sending unit, and if so, where is it located? Thank you for your time - great website!

J. E. Whelan said...

I would definitely take a look at the oil pressure sender. It will be located most likely on the passenger side threaded into the block to an oil pressure gallery with one or two wires attached. You obviously don't have a mechanical oil pressure problem.

Darrin said...

Thank you! Found the sending unit, cleaned the plug, and everything is fine. Thank you for your help!

Anonymous said...

John could you reconmend a good manual for a 97 3600 bus with a
E444T , 545 Trans..Right now need to change a water pump but I'm sure there be more to do. Love the blog.
Learned allot.

Sterling Abbott said...

John, We recently purchased a 2009 Thomas C2 with MBE 900. I read on your blog that Mercedes recemends 2yr coolant/ tstat change. I have looked on both AccessFreightliner & Thomasbusonline and can find that info. Is that just something you practice or directly from Mercedes Benz. If from Mercedes Benz can you direct me to that info. Thanks! Sterling.