I have two 700r4s that were rebuilt by the same trans shop (they are very good, know what they are doing and have been in business for a long time, so no blame there).

The problem is that they use the cheapest parts they can get and I happened to find out by accident who their supplier is. I bought some stuff there myself and they are definitely REALLY cheap.

The problem I am having is that both transmissions leak from the front pump seal. I also happen to know that the seal kit they used costs $20, so it's definitely an economy item.

So... I'm looking for a better quality front pump seal. I would like brand names and part numbers.

 

..... Same torque converter ? ..... it may not be true between the crank register and pump drive shaft ... what year trans ? the early pumps had a small pressure bleed hole behind the seal and the fix is to drill it out ... look in the ASTG book for dimensions ... high line pressures make the seal work harder and wear quicker ... I use Precision kits and they come with National seals ... I'll try to locate a part number for the front seal ...........

 

I would doubt a "cheap out" of the parts - you need to think realistically here. A transmission shop's profit requires builds to be a "once and done" - there's no profit in the "redo" and reputation suffers also. A redo costs the shop way more in $$'s than just the one job, shop space, wages and expenses just keep on going. If the shop didn't have confidence in their supplier they wouldn't be using them.

A misplaced bushing maybe in one but I'd doubt two. C409's recollection of modifying the return orifice is correct for the earlier 700R4's. You don't mention what year cores were used so there's no telling from where you started.

You're sure it's a pump seal leak? A pump seal leak is suspect or blamed many times and the real culprit is the t/v cable seal.

Also I believe in '86 GM started to cast a lip to index the bushing. I've read that you can trash the pump removing the bushing incorrectly. Does the ATSG manual mention that? I would think so but I don't have a need for one. There's much to check - I would doubt the "cheap out" of the parts is going to be a factor.

Perhaps you can just pull the seal and check the transmission that's "on the floor" - it was a build done by the shop also or is it the OE?

 

One 700r4 is the one I took out of my '86. It was rebuilt about 6 - 8 years ago by this shop. They used a rebuilt torque converter. I looked at the bushing and it has not moved forward and the drainback hole is not blocked. This trans is sitting on a trans jack in my garage. I took it out of the car because of the front seal leak. I need to sell this thing...

The second 700r4 is in my car now. It came from an '89 Corvette, so it has the lip to keep the bushing from walking forward. This one has a newly rebuilt Edge torque converter in it.

When the first trans was rebuilt I complained that they used a cork pan gasket. The owner told me they never had a complaint. I thought, "From mini van owners who park it in the street". In my experience the cork gaskets always get saturated with oil and eventually leak. That one started leaking right away, so I bought a filter and gasket kit and replaced it myself. Later on the front seal started leaking. That's why I took this trans out of my car.

The '89 trans was given to me by a friend who put a ZF in his car. His built 383 thrashed the 3-4 frictions so I rebuilt it myself with a kit from Pro-Built Automatics. It turned out that the trans had other problems (broken input drum and a snap ring came loose somehow) and I didn't want to deal with it so I had this shop rebuild it. The Edge torque converter was installed after they did the rebuild. Note that the front seal did NOT leak when I rebuilt it a couple of years ago with Dana's kit. The leak started after the trans shop rebuilt it.

Both transmissions are definitely leaking from the front seal. There is trans oil dripping out of the hole in the cover. There is no trans fluid around the dipstick seal and no leak at the cooler lines.

 

The GM/ACD seal hasn't changed part #'s since '94 so that would imply that they've not likely changed the vendor either.

The GM/ACD seal # is 24202535 and is very inexpensive, the retainer is GM # 8654491 and isn't available from ACD. It is assembled with the retainer?

How many flywheels? Still the original or is it a service flywheel done later in life?

Is it seeping around the metal cladding to the pump? Maybe this time use some sealant at that position.

I'm sure that it's aggravating as he!!

 

With the various problems I've had with these transmissions I've taken them out 4 times. I REALLY HATE that job. That's why I had the shop rebuild it the last time.

I have considered taking it back to the shop and getting some UV dye put in so I can pinpoint the leak. I suppose I could buy some somewhere but I have never had a need for it so I don't have a source. Another (what I call) treasure hunt.

The flex plate is the original.

I had thought about a possible leak around the pump O-ring. I think there is a drainback hole there. I thought about this possibility but I've never seen anyone mention a leak from this source so I didn't put it in my post.

I checked the 24202535 part number and it's listed for '84 through '96 transmissions.

 

The dye should be an easy buy most anywhere. There is a GM product 12345796 that has recently been replaced so I'd shop for the older number first. If they don't have that just ask for AT leak check.

There's many aftermarket products also. You mentioned earlier you've bought from the vendor the shop uses. I'd say if you really wanted "leak check dye" you wouldn't have an issue.

You know in your particular situation the original number for the seal was actually 8648394 and I'd think there's maybe still stock of that part number also. Then there's maybe an "aging issue" if it's older stock. Who knows?

 

I pulled out the original trans after 15 years because of a front seal leak. It was pretty discouraging to have it start leaking again right after I put the trans back in. I had a water heater drip pan under the car for years:



I ordered one of the 24202535 seals. I saw a reference that showed this number for 2004 - 2007 transmissions, so it's use is pretty widespread.

Now the problem is to work up enough enthusiasm to go through the hassle of pulling the trans to put it in.

 

You're going to do the dye? You did get a new retainer?

 

cliff, I am almost finished putting my tranny back in because of this very problem. I too, hate this job. Heck, I hate being so old and fat now which is the real reason I hate tranny jobs. While being out, I had the shop go ahead and rebuild the tranny and bought a NEW 2,000 stall converter. 800 bucks for the job with me pulling the tranny..as you can see in my avatar. I am gonna be very unhappy if I have to pull it again. good luck with yours.(1986)

 

I will use the dye. I want to be really sure I'm fixing the right problem. If I have to pull the pump that's OK. I made a pump puller and guide pins so I'm set there.

I don't think the seal retainer is necessary with the later pump that have the bushing lip but I put it on anyway.

The seal came today from CT Powertrain through Amazon. They have very low prices and even with the shipping it was way cheaper than some other vendors.

This is definitely a back burner project and how soon I do it will depend on my tolerance of the puddle on garage floor. Fortunately the floor is painted so it doesn't soak into the cement and it's easy to wipe up.

 

I would also check the pump bushings while your in there, assuming that is the leak problem.

 

What "branding" and packaging did you receive from the vendor CT? The retainer was used all years and not deleted just because the pump had the lip.

 

The bushings are all new. I told the builder I wanted them all replaced and he said, "ALL of them"? Apparently they usually just replace the ones that are obviously worn.

 

I Googled 24202535 and this listing on eBay came up in the results:

http://www.ebay.com/itm/350580119601...S:3160&vxp=mtr

I made a bad assumption when I assumed it was an AC Delco part. They show "TRANSTEC/NOK and/or NATIONAL" as the brand and later say "THIS IS NOT AN AC DELCO PART:: BUT IS 100% OEM SPEC PROFESSIONAL GRADE"

Now you're freaking me out. I don't EVER want to take that trans out again -- too painful, literally and figuratively. I'm too old for this stuff and I hurt for days after doing a trans R&R.

I didn't think I needed the seal retainer but I used it anyway.

 

what kinda money you wanting for that other 86 tranny>?

 

I haven't researched its worth yet. One thing I know for sure is that I don't want to deal with shipping it. It's going to be a "you come here and pick it up" deal.

 

Many years ago i came across this issue after sever quarter mile runs the front seal popped out, i removed the transmission and asked a transmission specialist about the trans fluid pressure issues forcing the seals out. He removed the pump and drilled a small bleed hole to prevent pressure forcing the seal out, a common problem he said and i have never had anymore problems with the front seal.

I know later model transmissions have a seal that clips over a ridge in the casting to help secure the seal, my latest transmission started with an 89 build date core that the builder said to start with as they have many improvements and stronger housing.
That has put up with my supercharged engine for years without issue.

 

The decision to do a buy anywhere other than "local" amazes me after you criticized the shops possible purchase practices. Amazing. If you're considering removing the pump you'll need the other seal and the sealing washers for the bolts. Some just reuse the sealing washers, I know some that do them always.

I checked a very responsible transmission supplier for the seal and even they offer a choice for the seal, one is a $2.40 buy and the other is a $5.20 buy. The less expensive is a similar part # with just a suffix added.

Some metal-clad seals are assembled with a sealing bead on the metal-clad sealing surface. If yours is NOT you might consider that or maybe ask your builder if you should.

I asked earlier about the flywheel and you mentioned it is the "original" - since yours is a recurring problem check closely the converter bolt mounting bores on the flywheel. Use new correct bolts this time? Fractures there could create issues. Was anything done to boost pressures in the trans?

 

The drainback hole has always been there. The modification involves drilling it out to make it larger.