Anyone know of a good durable pan gasket for a 700R4 auto trans? I replaced the fluid, pan gasket, and filter on my 82 after I brought it home last Sept. It has leaked ever since.

At first I thought it might be something else on the right side of the trans but now it leaks all the way around. I lose a pint in four weeks just sitting static.

The pan gasket I used came from AutoZone. It's not cork but some black material. The torque on my bolts are good and even.

I'm looking for a gasket that has the compression washers at the bolt holes. Any input is greatly appreciated.

 

The last one I bought had the compression washers. I just got it from the local auto parts place. Fel Pro?

 

I'm not sure the good gaskets are still made for the 700R4 (I know they're not for the THM-400). The auto stores just sell the whole filter/gasket kit with the neoprene gasket these days.

If you are left with cork or neoprene, I would suggest that you drop the pan, clean pan and housing gasket surfaces well with lacquer thinner, etc. to get all oil, grease, etc off of them, put a thin wipe of Permatex #2 sealant on BOTH sides of the gasket, place it on the pan rail and install it to the housing with very light torque on the bolts (1-2 ft-lbs). Let it sit overnight, then tighten the bolts again in stages up to full torque(7-10 ft-lbs.). Note: you want to balance the bolt torquing process so that you don't "oversqueeze" any section of the gasket during that process.

It should not leak again (from the pan).

 

Thanks for the tip. If I can't find one with the compression washers, I'll try this on the next neoprene one. The irritant on this is it wasn't leaking when I bought the car but it had been sitting for a few years and I figured fresh fluid and filter would be a good idea. I went against my adage of "If it's not broke, don't fix it."

 

You did the right thing to change the tranny oil and filter when you bought the car. But, the gaskets available now...suck! If you installed neoprene gasket on it, you can reuse it if you are careful when you remove it. Just use the Permatex #2 after cleaning the metal rails AND the gasket surfaces; it should seal just fine. You can also reuse the tranny oil, if you clean all the pan/housing surfaces well before you do the disassembly and use a clean pan to catch it in.

And, while you have it down, install a add-in drain plug so you can drain most of the oil first. You can find them at most auto part stores (I got mine at NAPA). Just drill the right sized hole in the pan bottom, insert the plug body, and install the retaining nut and washer. Good to go!

 

i believe the 700R4 pans are the same as the 4L60E pans. I would use one of the factory reusable gaskets that the newer cars and trucks use.

 

it takes only about 90 inch lbs.....any thing more will spit the gasket....i actually bought an inch torque wrench for this one and my pan hasnt leaked since....

 

About 6 months ago I rebuilt my TH700R4 and quickly ran into problems. At around 250 miles my transmission started blowing oil out of it's dip stick tube whenever I pulled the ten mile long hill coming home. I was very puzzled why it would blow oil out of it's dip stick tube because I knew I had only put 10 quarts in it. I dropped the oil pan and was shocked to see the filter come down with the pan (???). Upon closer inspection I found the filter seal had collapsed and didn't have any tension on it. Assuming I had just gotten a bad seal I replaced the filter and the same thing started happening within 250 miles. Once again I pulled the pan and found the filter came with it. One of the filters said "MADE IN CHINA" on it and the other said "MADE IN AMERICA". So I'm assuming the defective seals are being made in China and finding their way onto filters made in both countries. I finally solved the problem by putting three 3/32" X 11/16" X 7/8" Viton o-rings on the filter neck instead of the original kind (you can't buy them separately anyway).

 

If that were a widespread problem, it could be solved by gluing a small neoprene plug of the correct height to the inside surface of the pan just under the pickup tube area on that filter housing. Then it couldn't drop out of the hole in the main housing. I haven't had that same problem, so it might be that the pickup tube bore in your housing is oversized. {Or, it could be that the seal on that AutoZone filter tube is just chinzy cr@p!}

 

Be careful using sealant on the pan gasket-- on the right side under the 2-4 servo in the pan rail, there's a hole to exhaust 2-4 oil from the servo. Plug that hole, and it'll shift correctly one time. Oil can't get out of the servo, the band stays applied.

 

Nope, the filter seals were no good as after 250 miles their O.D. and I.D. shrunk about .020" to .025" and failed to seal. Upon taking the filter out I found I could place the seal on the filter neck and the seal would slide down by gravity alone. So I suspect the defective seals are being made in China and then sold to filter manufacturers all over the world. Just because a filter says "MADE IN AMERICA" doesn't mean it's seal was. Rather than putting a third new filter on I put three common 3/32" X 11/16" X 7/8" Viton o-rings on the neck and that cured the problem of sucking in air. I now have about 15,000 miles on this transmission and the filter is still tight. After I encountered this unusual problem I sent one of the defective seals and a new seal to my friend in Louisiana so he could see for himself what was happening. Like me, he had never seen a filter seal fail like that. As I live in the mountains I have a ten mile long 5% grade to pull on my way home. During the first 5 miles my transmission did okay but then it began blowing oil out of the dip stick tube and continued until I reached the top. I pulled over and checked my oil level and found it was showing 3" overfilled. But the next morning the oil level showed normal. So what was happening was as my oil thinned the pump lost it's prime and failed to keep the torque converter full. And as oil from the torque converter found it's way into the pan, the pan got overfilled and then the excess oil got shoved out of the dip stick tube.