6r80 transmission pan gasket dilemma

Maintenance/Repairs
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1

Can anyone help me? I have a 2013 mustang gt with the 6r80 auto and I believe it has a very VERY slow transmission pan gasket leak. I had replaced it just 2 days ago with an OEM gasket as part of doing a regular fluid change. Everything was torqued down to spec, 106 inch pounds.

Today I had it on a lift at a shop getting some other work done and we happened to observe what was maybe HALF of an eye dropper sized drop of fluid seeping through just one corner of where the pan meets the gasket. (This was observed while car was running in park on the lift and at operating temp).

Nothing was dripping, and just to give you all an idea of how little fluid actually appeared to be “leaking,” it was about a pencil thin line of fluid about half an inch long on just one corner of the gasket. Literally it was like someone took a regular ballpoint red pen and drew a line half an inch long, that’s how little fluid there actually was. It would probably not be visible if you were looking at it from more than a foot away.

I do know the very small amount of fluid we saw was a leak and not residual from servicing the trans 2 days ago, because when I replaced the gasket and reinstalled the pan and refilled with fluid I wiped everything off very well immediately after finishing the job and saw absolutely no red anywhere on the pan or gasket

Mechanic told me to just leave it alone, and given its current state with the leak being that small I agree it’s probably not worth messing with plus I really don’t want to do this job again or have to pay someone else to do it…

However I’m a little wary of driving it knowing it has any kind of transmission leak even a tiny one since this transmission doesn’t have a under the hood dipstick, so checking and monitoring the level is a pain in the ass!

My question is this: I have an obd scan tool that tells me trans temps, would it be feasible to monitor the level this way? ie if the leak got worse causing the fluid to get too low, would the temps will be noticeably hotter, then I’d know the leak had gotten larger and I’d have it get fixed? The shop i took it to verified the fluid level was correct, I then drove the car for over an hour and the hottest the trans ever got was 188. So in theory if the trans fluid became too low wouldn’t it start reading hotter and I would know I’d have to add fluid and get the transmission re serviced. But like I said earlier I don’t want to unnecessarily redo this job if I can’t help it

And also I just can’t be asked to get out my jack, jackstands, run the car for 30 min to get trans up to temp and then check the level next to the burning hot cat every single time i want to check the level. Using the scanner would definitely save me a lot of headache if this was feasible. Anyone have any input? Should I just not think about it, monitor temps using scanner or just suck it up and re do the entire job?

2

Replace the gasket with this product.

This is what OEM’s use in place of gaskets for the reason you’re seeing…

Tester

3

Should I use this on the OEM gasket or use it instead of the gasket?

4

You apply just the sealant, no gasket.

Tester

5

How long do you have to wait for the right stuff to cure before adding transmission fluid and before driving, after re installing the pan with the right stuff?

6

The time will be on the can. Personally, I don’t like those gasket makers. They’re fine…until the next time you need to do the pan.

First, did you make sure to get all of the old gasket material off and clean the surfaces really well? Second, some gaskets have a bit of “sponge” to them and I generally re-torque after a week or so, and haven’t found it unusual (even at something as low as 106inlb) to find some of them ended up needing a little more turn after the gasket compression. Third, how confident are you in your torque wrench?

And finally, even if it is leaking something like a drop a day, you’re not going to wreck anything. It will take longer than your next fluid change to matter at that rate. Talk to me when you’re leaving puddles under the car.

7

You can add tranny fluid one minute after the pan is installed.

Tester

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There was no gasket material to remove because only oem metal gaskets had been used previously. I just took a rag with brake clean and wiped the mating surfaces down to get an dirt or dust off before installing.

I did tighten slightly beyond 106 inch pounds because i have a mechanical torque wrench and i’d rather err on the side of slightly over tightening than under tightening since like you said bolts tend to loosen anyway overtime. Like i used a regular ratchet after the torque wrench and turned all the bolts a quarter turn.

As for driving it as is, yes a drop a day won’t hurt anything even long term, however I don’t know if/when the leak would worsen or if it would just stay the same, hence why I was seeing if there was a way to somewhat monitor fluid level using trans temps

9

And over tightening can warp the pan and cause it to leak, sometimes that extra 1/4 turn can do more harm than good.

1 Like
10

Which side of the transmission? The gear selector shaft is on the left side, oil leaking from that seal can run along the gasket to the corner of the pan causing the appearance of a pan gasket leak.

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11

Did you check BOTH sealing surfaces . . . the pan and the transmission case . . . for porosity, nicks, burrs, etc. . . . ?!

12

This trans uses a re-usable rubber gasket with metal inserts. If it sticks it tears. It is obvious as well.

The wiring for this trans comes through a big round connector on the passenger side that is notorious for leaking. It can be replaced without draining the trans.

You cannot detect low fluid from the temp sensor.

A drop is a very small amount of fluid. You can drive a long time without issue. Watch for puddles. Puddles are bad.

2 Likes
13

So the gasket compression is set by the height of these bushing inserts. The OP cranking down a bit extra is just distorting these bushings and potentially causing problems which, tightening more than recommended usually accomplishes.

Can’t tell you how many used vehicles with stamped pans or valve covers I had to tap the dimples back out of due to overtightening in a misguided attempt by the previous owner to ensure it didn’t leak (which it then did).

:grinning:
Man, I almost want to get this on a Tshirt!

2 Likes
14

I stopped using transmission pan gaskets about 45 years ago when I questioned the Plymouth dealer oarts guy why my transmission filter did not come packaged with a gasket like the aftermarket ones…

He said because the cars come from the factory with RTV sealer. Chrysler recommends aginst using a gasket. I personally find the RTV to be much more forgiving than a gasket.

15

That varies greatly by car design. Some Chryslers use RTV, and if the proper type and method is used, it will never leak. On the other hand, the Chrys/Mercedes transmissions that use a rubber gasket with only 6 bolts for the pan require the use of a gasket.

For transmissions that have a steel shim reusable gasket, trying to use RTV will guarantee a leak.

3 Likes
16

I was thinking the dimples may have gotten flattened out too or not tightening in an alternate sequence. On Gm anyway, those bolts seem to loosen up over time though and need to be torqued down again. Maybe just my improper tightening in the first place. I do like the idea of the leak being from the harness plug. Leaks can be deceiving.

17

I’ve never encountered that on GM trans pans with factory reusable gaskets

18

The leak seems so small that I’m inclined to concur with the OP’s mechanic, if you need to worry, worry about something else. As far as what’s causing it, my guess is the pan bolts were over-torqued at some point in the past, and that warped the pan’s sealing surface. Next time OP needs to remove the pan, clean it thoroughly then check the sealing surface under good light with a straight edge.

Over-torqueing isn’t uncommon, esp among diy’ers, when the repair manual spec is listed in inch-pounds. Valve covers, oil and transmissions pans. It is easy for a diyer to not notice the the non-standard-torque units, and torque to the same number, but in foot pounds, way too much.

Sorry you are having that difficulty w/monitoring the transmission fluid level. YOu’d think the manufacturer would provide a simple way to do that. Maybe they do, but it requires a tool only the dealership has.

19

Don’t do that. 1/4 turn is a lot. There’s no reason to go past spec, so just drive maybe 500 miles or so and check the torque again. Or at the very least, if it’s 106 inlb, and you want some peace of mind, maybe just set it for 115 or something. I’ve done a lot of trans pans as a DIY - it always “feels” wrong b/c that torque is low - but you just trust the spec. (Well, except if you’re working from a Haynes manual. I got burned once on misprinted torque specs for some brake work - trust but verify, I guess).

20

For years I bought slant six Chrysler products as “work cars” for $2oo or less, interrupting their trip to the junkyard for a couple of years. I would hammer pieces cut fro, the hoods and trunks of the one I was going to junk to patch the holes in the floor pans of the new one.

Inevitably, the aluminum case torqueflight would have several pan bolt holes stripped. I would cut the threaded part of longer bolts to make studs (I cad coffee cans of all sorts of used bolts.) I would then twist steel wool into thin lengths and with J B Weld into them and put them up into the stripped hole and hand thread the stud up into the hole and carefully wipe off any J B Weld that was not up in the hole. Never had any leaks afterward.