Detroit Engine Tune UP 42K Miles ??

[0533]

I seem to have a need to find new ways to keep the bus in tip top condition, and wanted to get some advice and feedback on Detroit Tune Up intervals.

Our bus has 42K miles on it, its now 10 ten years old, runs great. We have addressed many systems and upgraded much, but have done nothing along the lines of an Engine Tune Up. I have been told by Detroit Diesel that the engine break in period takes around 70K miles and that there is no need to adjust the valve lash and adjust or clean the injectors until about 250K, but I do not think that anyone has considered time as a factor.

Is it necessary (Any Benefit) to have a tune up before the book recommends it, is there any other reason other than miles driven, does time have any affect??

Is there any other service items, engine related other than filters, fluids, and belts that need service, upgrading etc??

[dale farley]

Bruce,

As a general rule, you are better off to leave things alone unless you are having a problem. In most situations with Prevosts and Series 60 engines, you will have to tear your bedroom apart to get to your valves.

My local DD dealer told me that if things are running good, don't mess with it. He said many times after making adjustments, you will end up getting worse mileage and may not gain anything in return.

[0533]

Leave well enough alone in other words?? I had heard about the bedroom deal, but when I looked in my engine compartment I thought there might be enough room to access the valve cover and the valves, but I my be wrong on this one, first today. You are also suggesting that the factory settings can be screwed up by the local dealer??

[Kevin Erion]

Bruce, first, I had a 99 Marathon XLV45 and you do have to tear the bedroom apart to get to the valve cover for removal. I don't think you need to look at the top end until between 80 to 100k. There are some that will say you never have to take a peak until it runs rough or different but I belive in a PM at 100K!

[0533]

Hello Kevin,

Thanks for the input. I wonder if Marathon has made provisions for this in the bedroom closets?

What signs to you look for when you refer to running rough or even different, at idle, fuel economy, smoke, pick up etc?? Are there specific signs to look for?

Who in our group has had their (Kevin calls the "Top End") and if so when was it required and what caused you to make the call?

I like to learn and stay ahead of these issues before they become serious.

[Kevin Erion]

Bruce, I did my 99 at 120,000 because I had the bedroom apart for new carpet. The engine was running fine but the tech did find a few things that needed to be taken care of. I have never had an engine that changed before and after a top end tune up so maybe it was a waste of $ but piece of mind has some value also.

[0533]

It is a lot about piece of mind.

[tdelorme]

Take it for what is worth. To me piece of mind is an engine that is running properly, has clean oil and filters and has not been exposed to some half trained jerk off that doesn't really have a clue how to adjust the valves on my engine.
Most diesel engine shops hate motorcoaches to begin with and the junior guy in the shop is going to be the one working on your engine. I know, your going to stay with the coach and watch what goes on and insist that the senior guy either does the work or at least supervises the rookie. Good luck, your in for a real crap shoot every time you walk through that door to the "service" department.

[0533]

Ted, please tell us how you really feel. My Detroit guys in Fort Pierce do not allow us to stay with the bus, in fact wanted it overnight. That is when I started to loose interest in the whole deal. At least at Prevost Jax you can be part of the process and learn while you pay.

[Joe Cannarozzi]

That is a shame.

I set the valves and bought new injectors at 55000 miles on an engine. It was running fine beforehand and ran the same after. It had another 500000 on it without adjustment and still ran the same when I sold it. It was a Cat done at Cat. I have to confess it did make me feel good.

Quoting Jim Scoggins "some of these things have a soul" and I agree.

People could try local excavating contractors to see who they use when they have major internal engine issues. Cat has a fleet of mobile mechanics with full blown service trucks that come out to these guys and do that stuff in the field if need be. These types are also found, sometimes, self employed and usually know their s--t.