Well,
I was tuning a 502/502 with a 700R4 this weekend and during an acceleration, the front seal blew out, and dumped tranny fluid for 1/8th mile.
We determined the cause was that one of the front bushings had slipped forward and eventually blocked off a return hole, which shot the pressure so high that the front seal blew out, and sprayed the car and exhaust and road with tranny fluid.
Anyone ever seen this before? Anyone know why the bushing slid forward? Could TV cable adjustment have anything to do with it?

We tapped the bushing back in place and put a new seal in, in a hurry. This worked, but later we called an expert who said we should have locktited the sucker in place .

What should be done in the meantime if anything (before time allows locktiting it) to prevent future problems?

Thanks,
Jeremy

 

It's been quite a while since I used to O-haul 700R4's, but I recall having to drill out the fluid return hole slightly bigger and installing a front pump seal retainer, per a GM service bulletin. This was a fairly common occurance on the earlier 700's. I don't seem to recall the bushing slipping out of place though.

 

excessive converor drainback will cause front seal blowout,however if the bushing circled its way out then thats why the seal popped out.the later 732 pump bodies have a step in them so the bushing cant come out of its bore.if you have an earlier model with no step you can grind three small grooves in the bushing bore,install the bushing w/locktite,and then stake the bushing into the three grooves.usually once it pushes out i wont use the body over again.also a misaligned hub on the convertor can cause this too.is it a new convertor?

 

Yeah, it was a completely new car - a 34 ford street rod (appraised at over $100k!). I really don't know what year the tranny was, but it was from a legit tranny builder I guess (no shortcuts on this car). It was setup for a non lockup converter, and it was new too. The car is in New York, so I don't have to worry about it anymore, but I just wanted your guys' input as to what could cause it for me to store away for my knowledge.
Thanks for the responses.

 

Exactly. the drainback needs enlarged on a few GM apps.

 

my original 700R4 did thid too.When I bought a new B&M Trans it had an extra retainer holding the seal in.Never had a prob again
PM

 

Blew my front pump seal out in November... The last owner changed the torque convertor but didnt change the seal. I was driving down the highway at about 80, lost 4th gear, started to smell stuff, then about 1 minute later, tons of smoke out the back of the car... im talking like total nascar smoke screen... it was pretty awesome actually. So anyway, i was in the woods and had a few miles to get to civilization, so I just mashed it and hauled a$$ It must have been pretty funny, cuz it was daytime, and i was passing cars at 80mph with 2 tons of smoke out the rear of the car. I knew the trans was toast so I didnt care about driving on it the few miles.