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View Full Version : Problem I did not expect, caused by routine maintenance



Petervs
01-16-2007, 04:42 PM
Since I was looking through old bus pictures, I found this one that might be of interest to some.

A picture of what is behind the transmission oil pan.

Why do I have this picture you ask? Well, I had the fluid changed one day, by the way we use 30 weight engine oil in the transmission because that is what the previuous owner had been doing with good results, so we kept doing it. When they did the change, they damaged some of the wires you see in the black plastic sleeve, these then shorted together at times and caused two gear sets to try to engage at once which results in an instant jolt to the bus as the wheels stop turning. Luckily it happened only while in second gear so the speed was low. Took the Detroit /Allison shop all day to troubleshoot and repair, all at no charge since they were the ones who caused the problem to start by their changing the fluid ( and removing and reinstalling the pan) which must have damaged the wires some. They ended up shrink wrapping the wires and tie wrapping them into position so they would not touch each other, and the last 40,000 miles have been trouble free.

Thought you might like to see how much electrical/ electronic stuff is actually submerged in transmission oil; all of which gets hot with the oil ( and retarder use if you have one). It is not just gears and bearings anymore.

All part of the fun Prevost lifestyle I guess.

Peter vS
94 Marathon XLV

Jon Wehrenberg
01-16-2007, 05:17 PM
We live in a computerized world and most of us drive computerized buses.

The 28 pin connector shown in the photo on our old coach got corroded (it was not supposed to) and the low voltage passing through the connector started doing some funky things. The corrosion prevented the two halves of the connector from separating and it had to be chiseled apart. The internal wiring had to be redone as a result. Allison and Prevost paid for the repairs.

The newer transmissions and motors have even more sensors and wiring. The good news is this stuff is pretty reliable, and I would never want to go back to the olden days of mechanical stuff even though the computer stuff is way beyond me.