Why to have your top end looked at!

[Kevin Erion]

Jon,
I DON'T believe this is an adjustment problem, I also DON'T believe it is a lubrication problem!
I looked at the valves ONLY as a PM. By doing this you get the only chance to take a look at things, I by no way am recommending that you tear down the motor just for the fun of it.
It is my opinion that Detroit Diesel has a problem with this area of the motor, like I said earlier, 2 for 2. I also have no idea how long the motor would have run before the cam would wear enough to effect the operation of the motor. I just feel better knowing this was done and I will do it again at 220,000 miles, God willing the economy holds up and I still have this bus!

[sawdust_128]

Kevin:

Did you get any kind of a response from United that they agree or disagree with your opinion on a Detroit issue?

[Kenneth Brewer]

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.

Jon is correct on this. This is a loss of lubrication or faulty rollers (heat treatment) - improper hardening. I wonder if the DDEC records loss of oil pressure beyond a time threshhold?

[Kenneth Brewer]

"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."

Jon is correct on this. This is a loss of lubrication or faulty rollers (heat treatment) - improper hardening. I wonder if the DDEC records loss of oil pressure beyond a time threshhold?[/QUOTE]

[Jon Wehrenberg]

I think Ken probably has it correct as being a hardening issue, but I will still stand by the fact that lubrication contributes.

If this was common the trucking industry would be all over this. But they run their trucks so long and so often the mating surfaces between the rollers and the lobes always have a film of lubrication between them. We who own motorhomes let them sit for long periods and the first start-up after that long period of inactivity is the problem. Any film of protective lubrication has probably drained down.

Once metal starts galling like that there is no cure, including lots of lube, and the rate of damage actually accelerates.

If properly hardened the resistance to that damage may be sufficient to mitigate the dry start up. Hats off to Ken for pointing that out.

[Kevin Erion]

I also agree with both Jon and Ken, but I am going with Ken's opinion that the hard face on the roller is not so good. Then with Jon's statement that after long periods of time between the motor running all the oil has drained off the parts and will magnify the problem of bad surface hardening of the roller!
Just FYI, last time when I did this to my 99, within 30 miles of us I found 110 roller rocker just for that model engine between 2 Detroit shops. Maybe that also leads me to believe there might be a problem with the part and not just us RV guys!

[hhoppe]

Kevin: You have the scored rollers why not send them out for a Rockwell hardness test. There is data showing what hardness they should be available somewhere. I tend to go with our intermitten use of our rigs causing these and a host of other problems. Possibly there may be an oil additive that will provide a coating on parts after the oil drains back into the pan. STP for one comes to mind.

[HarborBus]

I'm not as well informed on these kinds of mechanical issues and I don't know what everyone else thinks, but I view this as a REAL BIG problem with the Detroit diesel. Maybe this is one of those dirty little secrets that no one at Detroit will readily admit to or even discuss. I'm diaapponted and have lost some of that warm and fuzzy feeling I had about the bus. Our coach has just under 50K on it so I guess I'll be tearing up the bedroom and having the valves adjusted and the top end checked ASAP.

[garyde]

Its all speculation at this point. It would be nice to have Detroit comment. i have a very good Detroit Service center in Ventura. I will call them tomorrow and see what they know.

[LarryB]

Many of you may remember my "Check Eng. Lite" & "Stop Eng. Lite" issues this summer. This occurred after a 'Valve Adjustment and "tune up" at Pacific Power. When I limped back to them with the warning lites they found no active codes and wanted to re-check the valve adjustment. The rest of the story-----while checking the valves they found a couple of exhaust valves being held slightly open not by their adjustment but by the pistons on the jake brake head. Two pistons in the one of the heads looked like the pix Kevin posted----lack of lube or--?