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TH350 Accumulator Cover Seal

Chief Brody

Chief Brody

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I finally located the true source of my transmission leak. It is the Accumulator cover that is leaking.

I would like any advice on how to go about fixing it...can I do it myself or is it something that a transmission shop needs to do?

How hard is it to get the cover back on without specialized tools?

By the way, I found this great website that has all the transmission parts laid out in a schematic with hyperlinked part numbers...

https://www.wittrans.com/Schematic.aspx?Transmission=250/250C/350/350C

They have the accumulator cover and seal and just about everything else you could want...even a pan with a drain.
 
Where in the diagram is the part# you believe to be the cause of the leak. The accumulator(s) are inside the pan.
 
It is coming out of this round thing:

Accumulator.jpg
 
OK, got ya now. I'm more used to a T400...but start by cleaning the area really good with solvent, to remove all debris around the area. Then push in that outer aluminum cover with a socket, and extension if you have room, it only needs to go an 1/8" or so. While holding that cover in pry the metal retainer ring out of its groove. Now see that spring in there? It will push out the cover about 1/4-1/2" out of the bore. Enough so you can grab it by hand and pull it out. Watch carefully how that acc. piston, spring, retainer,etc go in order. Replace that Oring under the removed aluminum cover and reassemble. You should be able to do it yourself without a problem. Just make sure you don't let it fly out when releasing pressure off the spring loaded cover. And maybe print a copy of that diagram for reference.

Do you have the trans out of your truck, or is that a reference pic?
 
76zimmer said:
Do you have the trans out of your truck, or is that a reference pic?
Click to expand...


That's a reference pic...I found a Kent Moore Accumulator Cover removal tool on eBay.
I will have to do it with the tranny in the truck....

One of the things that I am unsure of is if my transmission is steel or aluminum...the covers and seals are different for each type.
 
use a magnet to determine the cover material....Put pressure on that cover squarely and evenly so it don't crack the cover when pressing it in, and when reassembling, clean the bore where the cover goes back in really good, and use some vasoline or trans fluid to lubricate the seal as it goes back in.
 
my pan is magnetic but the bell housing isn't...
 
use a magnet on that accum. cover, I bet its aluminum. All auto's used in our trucks are aluminum, and I believe all of them have a steel pan on them too.
 
I hope I am finally seeing light at the end of the tunnel on this transmission leak saga.

I ordered a new pan with a drain plug and a new bolt set from that wittrans company....got 2 seals in case I pinch one...it will take a few days for all of it to arrive, but I hope to be done with the leaks this time.

I hope the seal is enough to stop the leak...I have read that a worn piston can make it leak through the seal....

Since I already have the tool and stuff ordered I am going to do it myself, but I wonder what a transmission shop would charge to do that? I bet they could do it in half an hour...
There is so little room I am worried about getting it clean...don't know if I will be able to see or reach the inside area that needs to be clean before installing the cover.
 
According to the manual I used to rebuild my T350 this year it is the accumulator.

Chief, be careful with the accumulator piston, if you can avoid pulling it out, don't pull it out. The seals on the piston are teflon and cannot be replaced, you will need to replace the entire accumulator piston. You shouldn't need to pull it out, and it shouldn't fly out when the cover is removed.

As for the seal swap it is pretty easy to do and shouldn't take more than a few minutes. Clean outside the cap area before hand with some brake cleaner and a rag. When you have the cap off just wipe the area inside with a clean rag before replacing the cap. Try to remove any loose dust or grease around there so you don't knock any into the transmission.
 
My bad, on a TH350 it is called an accumulator but on a 700R4 it is called a servo.
 
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