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How often do you do top end adjustment?
Several resources on Detroit Diesel website indicate S-60 an initial adjustment at 70K miles and one says 100K is all required.
What is the general consensus of people owning coaches that are low mileage but aged in years for doing the tune up of valves and injectors. Frequency / mileage /time.
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10 Replies
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Based on many conversations with Prevost and Detroit service most shops will recommend top end service if one of these issues are present.
1) poor fuel mileage
2) Excessive black smoke
3) Rough shaking engine at idle.
4) poor jake brake performance
100,000 miles is the point to really consider top end service. Of course the owners who are pro active in doing preventive maintenance before a problem appears will do top end as there long term plan is keeping this coach.
Al
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Detroit says 60,000 miles. Many shops will say to wait until 100,000. I had issues with my first (2006) engine having an injector hold down come loose at just under the 60k mark if memory serves. I had that fixed as well as the complete tune up. Most of the valves and injectors were out of spec.
My second one (2010) was done at 60k as well. There were many valves and injectors either too tight or too loose in this one too. There is no reason to wait past the 60k mark that I can see. There was a noticeable improvement in engine smoothness and fuel mileage after the tune up.
I only paid about $700 bucks for the tune ups. Cheap insurance considering what it would cost if you dropped a valve or had other issues. Hell, the tow to a shop would cost more than that in many cases.
I now have a Volvo and will have that one done at the Volvo specified mileage too.
I also change oil at around 5000 miles. Oil is way cheaper than engines.
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Mark: Who did your tune-ups and if an X, did they pull the engine?
So you wouldn’t necessarily wait until the fuel mileage starts to drop off before doing the top service?
Once its done the first time … then do it every 100,000 miles or are you good for longer.
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If memory serves me correctly, one or more Prevost/DD owners discovered more than valves and injectors needing adjustment when they did the top servicing. Nothing catastrophic as I recall, but things that needed to be addressed anyway. Can’t remember what it was.
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Local Freightliner/DD shop did both of mine. There is no reason to wait and many reasons to do it at 60k. I had issues with the fuel being pushed back to the tank because the injector hold down had come loose and allowed the injector to move up in the head…just a bit, but enough to let compression into the fuel rail and send all the fuel back to the tank at shutdown. Every valve and injector were out of spec by quite a bit on that engine, and at least as much on my next coach by 60k miles. The injector hold downs were not loose on the second engine.
It is an old wives tale that you need to wait for mileage/performance to suffer. Mine sucked from day one, and got better after doing the tune up. The engines also ran smoother and quieter at idle after doing the work. Fuel mileage went up slightly, but not as much as I hoped it would.
The service writer tried to talk me out of doing them at 60k, but the engine mechanics said to do it. I will always trust the guy doing the work before some lower skilled guy just filling out a work order. I do not remember the mileage for the next tune up, but think it was somewhere in the additional 100k range. For what I paid, I would have done it again at the next interval specified. Cheap insurance.
They did not pull the engine in either case. In the XL2 I removed the floor panel in the bedroom which gave them enough room to get the valve cover off and in the H3 there was enough room we did nothing extra. The XL2 had a Jake setup and the rest have retarders FWIW.
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Dick – I think you’re talking about me, we found problems when I did the overhead on my 02 Marathon at DD in Ocala that could have been a big deal if left go. There were several Jake rocker clips that had fallen off and laying on the head. They installed an upgraded rocker that didn’t have the clip.
George – The previous link was corrupt and I can’t find the file.
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If you click on OVERHEAD link posted by Truk4u doesn’t work. Give a error with multiple causes for not displaying.
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See above..
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I did mine at 120M and found the same issues as Tom did. Rebuilt everything with updated parts.
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Bill where did you have the weekend to done?
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Dick. Had it done by Detroit Diesel here in Cleveland. Only one man did the work. had turbo checked too. it had a small leak at waste gate. Ended up as no big deal, but had to check. I’m too old to crawl around in there. All was done over two days.
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