904 Transmission Stopped Going Into Gear
View attachment 1715214352
Here is is by the way.
I agree with you but I'm kind of stuck on the TC problem.
I've heard people say:
"flush it, look into it at the splines and re-use if good" and also "always replace the TC, no exceptions"
There was gunk in the pan (see post #34 and 22), not sure how bad that is....
I would like to replace but the problem is that I cant find anyone around town that has them.
Where should I be looking for these? Buying a used one that I know nothing about is the same as me re-using mine, so I would need to find a "new" one.....thoughts?
Yea, no way would I trust that converter after all that was in the pan.
Think of that thing spinning at 2-5k and what the stuff in the fluid does.
It packs a fine powdered combination of burned clutch material and aluminum dust around the entire inner surface, and it's almost impossible to get out without having the converter cut open and rebuilt.
I seriously doubt flushing would even come close to getting that junk packed in the converter out.
I would do almost anything to not use that one again, as it's just to risky on a fresh rebuild.
I only replace bushings that are bad. That pump bushing looked pretty good to me; a lot of them show copper when new. The drum bushing looked worn, but also check the pump cover surface where that bushing rides and replace the pump cover is there's wear. Check the inside of the pump cover for wear from the forward rings. Also check the inside of the direct drum for wear from the direct rings. Any wear; replace the drum. Replace that converter. It looks worn in the bushing area and it might be grooved in the seal area. Check it for cracks emanating from the square cuts toward the front. If you stick your finger inside you'll find the weak spot of the 904; the converters are thinner forward from the pump tangs and that's what makes them crack. You can tap it and oil will come out of the crack; then you can see it. Bottom line, although the filter will protect the valve body and converter from contamination by large particles, the problem arises when new hot fluid hits the built up layers of contamination that have been compacted into the outer perimeter of the converter. While all of this has been a build up of very fine particles that can't damage much, it gets washed out in large compacted chunks that will clog your new filter again and again. Rebuilt converters aren't hard to find. If the composite thrust washers are brittle then replace them. Put a new on on the front of the output shaft. You can put two on the pump to reduce endplay.
The problem with not replacing the pump bushing is that it locates the pump gears in the pump housing by locating the pump drive cogs on the converter, so not changing it can lead to pump damage purely from the pump gears running off center causing low pump pressure and quicker drain back of the fluid when not running.
The pump tries to run off center anyway, just purely due to the function of the pump pressure pushing it to one side, so it's pretty darn important to replace it always.
If you look at one of those bushings it will be heavily worn on one area more than the rest, which lets the center gear of the pump get off center.
When that happens it starts dumping cast iron dust into the fluid and quickly distributed it through the rest of the trans killing it, and likely doing so much wear damage as to make the internal parts completely trashed and not even reusable.
The filter will not save the trans from that iron dust, and it takes the converter with it.
It's just not worth a 50 cent bushing to risk it.
Also have to be careful about stacking washers as to not get the sealing rings so far out of place that they don't direct fluid where it needs to go.
If you look in the drum on the other side of that bushing there are slots where the fluid goes through so the clutches apply.
To much washer can misalign the rings to the point the fluid can't get into the drum.
You or I might get away with different spacing, and I have done it before, but for someone new to it probably best to stick to normal endplay practices.:D
