Thread: Stock 700r4 Pump Case Leak

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In June I installed a 430 HP/452 ft lb of torque 383 SBC in my 1986 IROC Z, I knew that the stock 700r4 in the car would require upgrading in the near future, but it took less than three months for it to give out on me. It started with what I thought was a bad input shaft seal leak, so I pulled the transmission, changed the seal and reinstalled the transmission only to have the same exact leak.

Being that the car had sat up for several years before I bought it, I was kicking myself for not changing the pump O ring seal while I had it out and so i removed it again and changed out the pump O ring seal, which looked a little dry but didn't appear to be cracked. Much to my dismay I reinstalled the transmission only to have the same leak again.

At this point I figure, that even though the transmission shifts good, something must have let go inside and cracked the pump housing case, so I pulled the trigger on a new 700r4 Level 3 Raptor Transmission from PATC. I should be able to get it installed and back on the road this weekend, fingers crossed that this is the last transmission I'll ever need to put in this car, as they are not cheap these days.

If you are talking about the front bushing behind the torque converter and input shaft seal, it seemed to be fine, I know it hadn't walked out any; hair line crack?

The engine is new, a professional build and runs at around 180 degrees all the time, I'm running a good transmission cooler as well as a brand new Be Cool heavy duty automatic transmission radiator; there has been no signs of the transmission running hot, the fluid is clean and bubble free when running. I drained and serviced the filter when I pulled the transmission the first time and found no metal or trash in the pan. There are absolutely no engine vibrations going on and the torque converter was a brand new Hughes with a 2500 stall, the only thing reused in the build was the transmission and the torque converter felt good and snug on the pump. For the record, I also bought a new 2600 stall converter from PATC with this new transmission so that everything will be new.

I also plan on tearing down the old transmission and finding out exactly what went out.

The new level 3 Raptor 700 transmission is installed and all I can say is holy cow, I had no idea how bad off the other transmission was; it's obvious that I was losing a lot of horse power through the stock transmission.