After leaking for a good while, the front seal went out in my 700R4 a few weeks ago, and when the car is running, it gets a steady stream leaking between the oil pan and bell housing. I called the "transmission guys" in town to see what they charged to change it. I explained to the guy that it had been leaking before, and that i'm guessing the seal finally gave out. Told him my car, and he gave me a story about the early 700R4's had a common defect in them, and that he guarantees that if he replaces the seal, it will blow within a day or two, and to fix it, I will at least need the seal, pump, and some other stuff replaced for $900, or fully rebuilt for around $1500. He said either that, or find one that's 87' or newer out of a donor car because they fixed the problem after 87'. Now i'm just here to see what any of you know what he has said is probably my real problem or not.
I picked up a used 700R4 out of a 2WD 88' blazer for $300, it's a little worn out but they say it works. It will cost another $300 to have it put in, if it even works right. And now i'm having my doubts. I have a week or two warranty to take this transmission back. Should I swap it out? Or am I wasting my time and money and really just need a new front seal? I checked the ID on the new trans, and apparently it's only an 86' anyways. Thanks.

Also, I wanted to add, that the transmission runs fine. The day the seal went, I drove all the way from wal-mart to my house ( About 8 miles ) And didn't even notice it was leaking until I saw smoke from the tranny fluid running on the exhaust when I got out of the car. I've been starting it every few days. And it still catches all the gears just fine.

 

Hopefully the Blazer had a 2.8 also so the bellhousing bolt pattern matches?

I'd drop it myself and replace the seal or find someone on Craigslist who will do it for a bit less than $300.

 

Yeah the blazer also had a 2.8L. I don't know how, or have a way to even get the car up high enough to even take it out myself. But i'm thinking about taking this tranny back, and just replacing the seal. Save a lot of money, and get money back to put into other stuff for it.

 

The "fix" for this is to remove the front pump and enlarge the "drain back" holes in both sides of the pump. This way the fluid will have an easier way back to the pan without putting pressure on the front seal. The TransGo Senior Shift kit recommends this for all early units and has the instructions on how to do it in their Shift kit. GM did this in 1987 and up transmissions. I do this to all pre-1987 units.

 

Ah. I thought I had heard something like that before, but I wasn't sure about it. They aren't wanting to do a return on the transmission, even though its an 86, when they said it was an 88' out of an 88 blazer. It's in decent shape, and should work, comes with torque converter and fill tube and cooling lines still attached. Do you believe I could resell it on say like craigslist and get my $300 back out of it? I really want to keep mine and save the hassle of this one not fitting right or anything.