This motorhome has 80,000 miles. I have had it the past 28,000 miles. Also has a Banks Transcommand since I got it. Holds 16 quarts ATF. At 52K I had half the fluid drained, the filter changed, and refilled with Mobil 1 ATF. At 72K I drained 14 quarts and refilled with Mobil 1 ATF. At that time a used oil analysis showed:

181 ppm copper
77 ppm iron
87 ppm lead
31 ppm silicon

Only the lead and silicon were flagged abnormal. Lab comments were: "Suspect clutch/disk pack damage....monitor at next service interval..."

This tranny has performed flawlessly since I got it (except for the soft shifting that the Banks fixed). A few weeks ago I was returning from a 100 mile run and noticed sitting at a light that the motorhome was shaking some, kind of like a rough idle, but the tachometer was rock steady. Put it in neutral and the shake was gone. Air conditioner seems to worsen it but not sure. Anyway it is present when in gear. Also notice some roughness when accelerating from a stop slowly, but if I give it a lot of pedal it seems smooth. Also smooth while driving along the road.

So is it the tranny, or could there simply be a vacuum line loose?
Maybe I should pull a sample and get another analysis?

 

You have slight engine concern.
A plug, wire, going bad.
With the added load of idling in gear with the A/C on it will show up.

 

Wow Stewart. Thanks. That is wonderful news. In fact I just had new plugs, cap, and rotor about 250 miles before this. The wires are 28000 miles old though (from 2001). Guess the first thing is to make sure the plug boots are all on tightly, but new wires may not be a bad idea. Also, I know the PCV hoses are kind of hardened and may not be a perfect seal. And I suppose the tach will not show it because it connects to the coil which is before the problem. Yeah, check the plug boots and maybe new wires. Auggggh. Too bad I didn't just have it done when it was in the shop. Oh well. Thankfully not the tranny.

 

The problem is gone. I found one spark plug wire that was wrapped down across the exhaust manifold (actually nearly pinched between the exhaust manifold and the engine cover). I moved it back above and today we drove 20 miles and the engine was smooth at idle in gear. Strange how a little thing like that could affect it so much--if that was the problem, or maybe it was something else that just happened to go away at the same time.