EricFJ80

Hi Folks,
I have a 4L60 & Gen3 5.3L swapped into an 80 series Land Cruiser. Engine & trans had about 91K when I swapped them and I've put on about 20K since then. When I had the transmission out I took it to a good local shop to swap the tail shaft and refresh the internals with the goal of towing & offroading performance and reliability. I had to replace the original pan with a shallower one for front driveshaft clearance - used a stamped steel one from Summit.

The trans had developed a leak which seemed to to be coming from the mid point of the drivers side of the pan, which steadily got worse to the point where it was a pretty slow but steady drip. I ruled out the shifter bushing as the source of the leak.

So I dropped the pan today, replaced the filter and gasket with a Duralast kit. Nitrile gasket. The old gasket seemed to be paper. It looked to be in good shape when I took it off. Came off the transmission and pan cleanly - no scraping needed.

Put it back together and torqued it down according to the instructions with the gasket & filter kit. 80 in-lbs in a criss-cross pattern, then 120 in-lbs in a criss-cross pattern. Then went around in a circle to make sure I didn't miss anything.

Refilled it again - and when I got to the end of the 4th quart I heard liquid leaking. Look under and it's leaking really badly - again at the pan on the drivers side!?!

Any ideas? I didn't do anything else while I was in there, other then pulling the driveshaft to give clearance to get the pan out.

The only thing I can figure is that pan is warped for some reason, and the paper gasket swelled to some extent to mostly seal it. For awhile at least. But the nitrile gasket isn't doing that.

So suggestions welcome. Not looking forward to dropping the full pan again. I bought a drain plug kit, but ended up not installing it because it seemed a fair number of people had problems with them leaking.

91 Z28

iTrader: (3)

Try tightening it up more in that spot first, Before you pull the pan again mark the spot it's leaking from then after you've pulled it place it on a flat surface to confirm whether it's warped or not. Also check that spot on the transmission case for any nicks or anything they could make it leak.

I think your pan is just fine most likely just those crappy gaskets. Do they make reusable gaskets like the 4l80e has?? If they do put one on, if they don't then I'd do away with the rubber gasket and just use a good bead of RTV

Tommy42088

I've never actually torqued an oil pan gasket, i always just clean the **** out of them and then hand tighten until it seems pretty snug. I'd tighten it up some more, may need to put some high temp rtv on it if that doesn't work. Tbh it doesn't sound tight enough though unless you have some trash or debre in that spot that you didn't notice.

EricFJ80

Yea, I tried snugging it down some more. Not change. It's hard to imagine how it can be leaking this much past the gasket.

I tried laying a straight edge on the pan, but it was tough to tell because it kind of has this raised area that isn't straight down the whole length. I should have layed it on a flat surface instead.

EricFJ80

Is this what you mean by a reusable gasket?
https://www.summitracing.com/parts/lub-llt-g4l60

Tommy42088

You sure it's actually leaking and your not over filling it? The overflow is on top the transmission and could possibly leak down the side of the transmission making you think it's leaking when it's not, just a thought. If not then take it off and put some rtv on it and make sure the mating surface is 100 percent clean and free on anything.

EricFJ80

I guess it's possible. Dumped 4 qts in because I read somewhere that it should take 4-6 quarts for a pan drop & filter change depending on the pan.

Something else that's weird though... when it started leaking with that 4th quart, I went ahead and started the truck. I think the leaking at least slowed down. But I didn't have any reverse? It was pulling in drive, but couldn't move based on how I was parked.

So I pulled the dip stick. I find the dipstick on this frustrating - there's fluid on it, but not like a well defined level line like when you check your oil. So I usually judge by whether the holes by the marks on the dipstick have fluid in them. They didn't, so I added another quart with the engine running. I don't notice more leaking. And now I have reverse! So I take it out for a test drive. Seems ok. Get back and don't notice much leaking, but as soon as I shut it off, it's pouring out again.

I have no idea at this point.

Here's the pan I'm running. Nothing special, but it's AC Delco so can't be to bad, right?

https://www.summitracing.com/parts/ado-8667545

Tommy42088

your over filling it, my truck did the same thing when I over filled it. It was fine when I had it running but when I turned it off it poured out the overflow. Look on top the transmission and you will see the tube on the top of it. Also when you fill a transmission your supposed to have it running and go through every gear while your filling it and continue to check it. Also did did you modify your dipstick to work with the shorter pan? Keep I'm mind you had a much deeper pan originally so the full mark will be much different on that shorter pan. Your should of put the dipstick in the fill tube with pan off and made new marks on the dipstick to compensate for the new pan, you would want the fill mark to be a little over the flange, also even if you weren't over filling it if you didn't run it through the gears while you were filling it then you were basically forcing the fluid into it and it can spit it back out the overflow.

91 Z28

iTrader: (3)

Yea I think that's it. But the one on my 4l80e is just an OEM reusable

bbond105

If the dipstick is not bottoming out on the oil pan the full mark should be in the same okay. the transmission is full when the fluid is just a little above the oil pan rail. With a filter change 4 to 5 quarts is not enough fluid to over fill to where it will come out of the vent.
What is happening here is when the trans has the proper amount of fluid, the fluid will be above the pan rail around about an inch with the engine not running. Once the engine is started the trans pump is sucking the fluid out of the pan and charging the torque converter bringing the fluid level down to the full mark on the dipstick, which is at the pan rail or a little higher and when you turn the engine off that fluid drains back into the pan bringing the level back above the pan rail again.

As for gasket I will only use a quality cork gasket with a stamped steel pan. Torque the pan to 8 or 9 foot pounds. Most auto part stores sale cork gaskets are too thin and the other types of gaskets are nor pliable enough. I get my gaskets from transmission parts suppliers like Whatever It Takes or TranStar. Whatever It Takes has a website that anyone can order from.

Once you have the pan off check the bolt holes, a lot of times the metal around the hole will become raised up and you will need to hammer the raised up parts back down. To do this support the pan rail on a block of wood or vise and using a ballpeen hammer, gently hammer the raised area back down. Once the pan rail is somewhat flat the cork gasket should seal it up. Just be sure not to over tighten the pan. Just a note I never use RTV to seal a transmission pan.

I hope this helps

vorteciroc

No.

The Company that GM worked with to Design the Gaskets for the LS Engines (Gen-III/ IV/ V SBC) also did the 4L80E Inspection/ Oil Pan Gasket (and the Allison 1000).

The 4l60E did not... it received the same gasket that was Designed for it for the 1982 Model Year THM700-R4.

tayto

this is a great gasket, but expensive. i don't like cork or the rubber gaskets that always come with the filter kits.

91 Z28

iTrader: (3)

Yea the reusable gaskets are where it's at. Being able to peel it off do your service and put it back in and tighten it all up is mint

MaroonMonsterLS1

Make sure pan and case are clean and flat
Cork Gasket
Torque to 108 in-lbs
Go around the circle of bolts twice

If it still leaks...either the case has a crack or the pan is not flat...or your leak is coming from somewhere else

Done 100's this way without issue.

Tranzman

Moroso makes a re-usable pan gasket for a 4L60E/700-R4 Took about 30 seconds on Duck Duck Go... Summit Racing or Amazon

https://www.summitracing.com/search/...&keyword=93104

bbond105

Holy Cow, Batman. There's no way I'm paying that much for a gasket, when a $2 cork gasket will seal just as well. I can buy 21 cork gaskets for that price.

reubone

Don't forget if you are going to rely on bolt torque, you need to chase and clean the bolt hole threads. You will also need to make sure that the bolts themselves are clean and undamaged. I have seen damaged bolt holes that feel good when tightening, but leave a gap before clamping the pan. Just a thought.

Y2K_Frenzy

Make sure the pan isn’t bent or warped.
The OEM gasket is made of Farpak and it works well. It sort of melts and seals like tar paper. This for a “shallow” car pan. But farpak is what you want. I bet the pan is bent though if it’s leaking out real fast.

vorteciroc

To put things bluntly...

A quality Cork Gasket (Yes there are junk Versions) is something that is going to take some trial and error for the inexperienced.
Honestly experience or just practice will provide successful results.

The pan Rail of a Stamped Steel Pan with a "Raised Sealing Ridge" will require attention ensuring a Straight/ Level surface and mounting holes in good order.
A good Case Mating Surface and excellent Fastener Threads in the Case are required.

Because of these reasons, so many other Gasket types exist... and RTV (and honestly i would stay away from it as ATF can break down many RTVs)
Note: there are ATF intended RTVs.

I would avoid RTV if possible.
Some of the other Gaskets can work.

Y2K_Frenzy

I think the 80 in lbs plus the additional torque to 120 in lbs might have bent the pan. That or the gasket slipped.