Trans pan leak

What I know, and what I've done:

I've read through the trans leak posts here and elsewhere.
I flat hammered the stock pan lip around the bolt holes. It looked reasonably flat before I put it back on.
I changed the filter and gasket (rubber). No sealer was used.
I torqued it to spec 120in/lb alternating the bolt pattern.
I drove it to operating temp (about 20 miles)

I know its leaking from the front right pan/gasket area.
I went under and snugged up the 3 bolts in that corner.
I drove it to operating temp (about 20 miles)

It's still leaking just as bad from that spot. Not just a little, a 3'x3' cardboard is wet to the edges...I know cardboard is like a sponge but that's really excessive.

If I have to take this thing off again, and take a trans fluid shower, I want a new pan with a drain plug. I'm open to any suggestions that I have not tried, but I'm pretty sure I want a new pan.

So... If you were going to buy a new pan for a 71' GS TH350 what would it be? And why?
I'd love to hear some success stories!

Thanks

 

you sure 120" lbs is correct. thats 10' lbs and thinking thats to much. My oil pan specs at 14" lbs which is a bit more than hand tight with a 1/4' drive.

 

Wow that's like 1.166ft/lb

I'm not exactly sure... A search for "TH350 pan torque specs" are all over the map from 8ft/lb to 18ft/lb

This thread says 13ft/lb http://www.v8buick.com/showthread.php?257862-Th350-pan-leaks&p=2220497#post2220497

 

Do you have to use the pan you have? Why not just buy an aftermarket aluminum pan with a known flat and true surface. Torque it down to 8 lbs. or so using the provided gasket. A new pan would be around $100 or so for the better aluminum ones with the thick mating surface.

 

That's what I will most likely end up doing. I was wondering which one people were buying?. Summit? OPG? Doesn't really matter?

I found the factory torque spec in the chassis manual: 13 ft/lb

 

I would be sure its the Pan and Gasket. The area you say is leaking is where the dip stick tube and the lines are. It could be those flowing down and making it look like the Pan is leaking.

 

I'll definitely re-check that. I did a good spray down with break clean and wiped everything off real good after I re-snugged up the bolts in that area. I didn't see any fluid coming from above the pan but I will make sure.

Thanks!

 

I've been chasing around a leak on my TH350 too. So far I've replaced the gasket no luck and replaced the pan and gasket with no luck. Mine is leaking from the left front corner. I torqued the bolts to 12ft pounds. At this point I'm pretty sure mine is leaking from the shift shaft seal. Like someone mentioned yours is on the other side and could be the trans filler tube. There is a o-ring that goes on that. Anyway I got this pan as a replacement. Looks nice and has the drain plug. Price seemed fair too. http://www.jegs.com/i/Proform/778/141-250/10002/-1 In my case I tried a the thin neoprene gasket and currently I have a thicker Mr Gasket cork/neoprene gasket. Good luck.

 

I was going to answer and tell you the leak in the Left front area is Probably the Shifter Shaft seal but you found the answer yourself.

There is a deeper shaft seal for the shifter that you can use. It puts the sealing surface at a different spot on the shaft. Talk to a "OLDER " guy at a Trans shop and he probably has some extras laying around.

 

Although not a TH350 or 400 I've a done a few pans on my late model Fords. I found the Felpro gasket to be virtually worthless and instead love the Victor-Reinz. It is a double steel o-ring sealed up in neoprene, and reusable. I don't know that they sell an equivalent for the GM tranny. Regardless my OEM stamped steel pans are not quite flat at the flange but it mattered not to this gasket.

 

I had a leak from the dip stick tube. all i did was replace the O ring and and some RTV. BOOM problem solved !

 

It's nice u flattened all ur bolt holes, but the way it's done is with the rounded end of a ball ping hammer or is it pin hammer, with round part on the hole strike the head of this hammer with another hammer, with the pan rail on edge of bench or block of wood, the idear is to have the hole evenly pooped outward away from gasget , then you just tighten snug and a quarter turn,

 

Ok, so I went and installed a new aluminum pan from Summit, with a Moroso gasket a few weeks ago.

http://www.summitracing.com/parts/sum-4338856
http://www.summitracing.com/parts/mor-93102

Still have a leak

I'm putting it up on the lift next weekend to look it over again. I want to have all the parts I may need, ready just in case I find the problem.

So, for a 71' TH350 do I need a grommet or oring or should I just get both for the dipstick tube? Also what do I need to seal the shift linkage?

If anyone has correct part numbers and/or preferred suppliers that would help a lot!

I also would not be opposed to replacing the dipstick tube entirely, but...I've read where aftermarket ones didn't work out well for some people. I don't want to create a 'new' problem lol.

Any help would be appreciated.

Thanks,
Storm1

 

I did the filter change in the 4L80E and the factory gasket is a ringed neoprene but the kit came with a rubber gasket so first correct thing is to use it RIGHT! yea I saved original so I could take off the new one after a couple days and put it back on [17] bolts 2 take as long as 15 it does have a plug anyway

 

Yeah those 2 bolts back by the trans mount are a pain in the A$$ ..

 

Still looking for some words of wisdom on this. Anyone have good results with oring or grommet or replacing the tube completely?

Orings for shift linkage, good vendors?

Sent from my SM-T210R using Tapatalk

 

Kevin. You really need to figure out where the leak is coming from instead of indiscriminately replacing seals . Any local trans shop probably has whatever seals you need left over from other jobs. They would probably sell them to you cheap if not just outright give them to you.

 

I'm putting it up in the air this weekend. I just thought it would be a good idea, since they are so cheap, to have them on hand if I need them. I was hoping to save some time.
Good idea on the trans shops. Ill give a few a call and see if they have any laying around.

Thanks

 

It would be better if you walked into the shop and Say something like " I hope you guys can help me out . i want to replace the external seals in my trans and was hoping you might have some "left-overs " laying around. "

Don't go to AAMCO or chain shops. Go to a Independant.