Why to have your top end looked at!

[Kevin Erion]

This is my 2nd bus and the 2nd top end tune up. On both buses I have had to replace 3 roller rockers due to what looks like the surface starting to fail. On this bus one of the cam lopes also started to fail. So in my opinion the top end should be looked at somewhere between 100,000 to 120,000 miles. It would have been a lot less $ if I didn't need to replace the cam.
Ray Davis is kind enough to post these pictures.

[Ray Davis]

Here are Kevin's pictures ...

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IMG_2165 (Large).jpg

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[sawdust_128]

Were there any symptoms that made you check for something?

[Jon Wehrenberg]

Kevin,

I experienced that on a plane engine once.

I used to do oil analysis every oil change which I was doing at 35 hours. They always came back normal and there were no trends such as a rise in any of the elements.

That galling shown on the rollers happens almost instantly and is attributed to lack of lubrication. I'm not sure anyone could have seen that or any signs it was about to occur until after the fact.

At least that was the case with the plane engine.

[lonesome george]

Kevin, thanks for the post and sharing the ugly truth, sorry your cam got wiped out.

I believe the Detriot service manual states the first valve adjustment should be done at 60K, mine is about at that mileage, so the time has come, it looks like a pain to do in an XL. Most Diesel mechanics I've talked to say the valve train in a Series 60 should be maintained every 100k.

I have seen cams go flat in new engines that were still on a dyno, it can happen in a hurry.

[Kevin Erion]

This is only my opinion and the fact that 2 for 2 is 100%, not good odds.
I think there is a problem with these rollers and if you don't catch it soon enough, the pictures tell what happens next.
I did buy all my parts from United Engines and they are the best!

[rfoster]

Kevin, the outside and bottom exterior of your engine looked slicker & cleaner than those parts. Sorry to see and hear of your problem-

What where the synptoms that prompted you to tear into it?.

[James]

We just had the valves done at around 64,000 miles by Pacific Power. The tech stated that everything looked good. He did find a jake brake connection that was loose and fixed that.

He also recommend that the valves be looked at every 50K to 60K. Kind of a pain to take apart the closet and then put it back.

Has anyone ever modified the closet step on an XLVII to allow the valve cover to be removed without having to take the closet apart?

[Kevin Erion]

There was no reason other than preventive maintanance to take a look and adjust the valves. I asked my mechanic what the symptoms would be if the cam started to wear more and the answer was rough idle, power loss and lower fuel milage. He also said that with the computer, it is hard to notice this at idle because it will compensate for the cylinder starting to fail by increasing the idle speed to keep it at the preset idle.

[Jon Wehrenberg]

Kevin......correct me if I am wrong. In fact use caps if I am misreading this because a lot of guys are going to be rushing to DD as a result of your post.

Your problem was not caused by valves out of adjustment. It was only noticed as a result of having the valves adjusted.

Going further, an engine can have its valves adjusted and before the next oil change this problem can show up. This is not an adjustment issue, but a lubrication issue.

Correct??????