GregN

Hey guys. I just picked up an '84 Berlinetta 305 for $320. At just over 100,000 miles it needs some love but I'm slowly getting it running right. I have a pretty bad leak (about 1 drop every two minutes with engine off) coming from the metal dust cover (?) hole at the bottom. I'm told it's the front pump seal. To replace that I have to pull the tranny. The engine is stock and the car shifts fine when there's fluid (HA), and I don't plan on building the engine much beyond 200 hp. Should I leave the tranny alone and just fix the seal. Or should I rebuild it since I have it out? Does the Transgo kit require pulling anything but the valve assambly? I rebuilt the 700R4 in my wifes Blazer a couple years ago, so I'm a bit familiar with the process and don't really feel like digging that deep into the tranny again. Thanks.
Greg

Kenwood

iTrader: (1)

Greg:

I had the same problem on my 85 corvette...Shifted perfect and no problems BUT it was the front pump seal...BAsically the LARGE o_RING that goes around the pump...I did not do a rebuild...I just bought all new seals and replaced them....It took like a full day start to finish but mainly because a vette is more complex to get the tranny out because its PART of the center structure of the frame...so you have to shore up the motor and the rear while doing it...BUT the problem I had was GM only sells some of the seals in certain quantities...So for instance my tailshaft was leaking a little to...But I now OWN 4 of the seals because the min buy was 5...But for the pump only you Need the front pump o-ring, front pump gasket, and the little rubber o-rings for the pump screws, and since the trany would be out I woiuld go ahead and replace the center pump seal because if you dont chances are it will start leaking the day after you are finished...

Pro Built Automatics

If you replace the front seal only, then the problem will come back almost immediately. The bushing will have to be replaced also. this should stop the leak for awhile. Another reason for this is that the drain back hole in the front pump is on the small side, and when the clearance gets on the high side (the clearance between the front pump bushing and the torque converter) the volume of oil is now to much for the front pump seal as there is nowhere for the excess fluid to go. The passage can be opened up as per instructions in the Trans-Go Shift kit. You might do this (front pump modificatioins) in the future when you rebuild the unit. The bushing & seal can be replaced without taking out the front pump if the proper tools are used, if the the front pump is taken out then do the drain back modifications and be sure to use the teflon bushing in the pump instead of the babbitt.

GregN

Forgive me. It's been a while since I did this. So I can pull the tranny, remove the pump, tear it down, enlarge the drainback hole, check clearances, and put it back together with new seals and o-rings and I won't have to mess with anything else other than taking the pump only into a shop to have the old bushing pressed out and a new teflon one pressed in? Correct?

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Greg N.
1984 P.O.S. Berlinetta LG4

GregN

...Oh yeah, and pull the valve body to add the Transgo kit.

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Greg N.
1984 P.O.S. Berlinetta LG4

rocn7roc

I have 91 700r4 if there is a lip on rear of front pump bushing , can it be done with out pump removal and what tools would I need Thanks

morgsie

iTrader: (1)

No. Way to bring back a 12 year old thread...