Blown Head Gasket

[Peterbylt]

The Governor and the modulator were replaced with new, no change.
As soon as I got the RV back from the transmission shop it acted up again and would not shift out of first all the way home. A different shop recommended replacing the Valve Body.
So, I found a used transmission on Craigs list, a Heavy Duty low mileage TH400 out of a wrecked 87 Coachman Class C, didn’t want much money for it so I took the 50 mile ride to get it. Looked pretty good, Seller seemed to be a nice guy so I took a gamble and bought it.
Put in a new filter and the new chrome pan, the inside of the transmission was spotless, the old filter looked like the original was very clean. There was no sediment in the pan, it did not look as though it had ever been opened.
Also swapped out the tail housing, Modulator, Speedometer gear, shifter linkage and driveshaft yoke.
Spent most of the weekend swapping out the transmission.
Success! Test drive is very positive moves forward and backward shifts smoothly when it should, no slipping and no leaks.
Have only driven it about ten miles or so, longer ride scheduled this weekend.
But, looks good so far.



When I took the pan off the original transmission it was spotless inside, I will most likely tear into it, I would very much like to figure out what I did wrong with the rebuild, I hate to have a transmission full of new parts go to waste.

Transmission fluid gets expensive at almost $20 a gallon and 3 gallons each time I swap the transmission.

Peter

[legomybago]

Bummer on the old tranny...That would definitely give me a headache