4l80e leaking and draining

[Daveo91Burb]

I noticed a lot of fluid on the floor about a week ago, haven’t driven it since because of that. Kept leaking the whole time and noticed it was dripping off the the back of the pan gasket. Last night I finally got to draining the pan (it has an aftermarket plug), but I didn’t drop the pan until midday today. There was a **** ton of fluid in the pan when I did!

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And I found this broken spring in the bottom of the pan:

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And it’s still dripping! Dripping off the back of the valve body, right at two electrical connectors:

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Anyone know what’s going on? Is there a busted anti-drain back valve or something?


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[yevgenievich]

All fluid drains in to the pan naturally and it will keep dripping for weeks. But the spring not sure. When not running the fluid level usually above the top of the pan.

 

[Daveo91Burb]

All fluid drains in to the pan naturally and it will keep dripping for weeks. But the spring not sure. When not running the fluid level usually above the top of the pan.

Cool, wasn't sure if the not-running level was above top of pan or not. Good to know that it's supposed to be. Seems weird that the gasket would fail all at once like that. It leaked when I first put fluid in after I got the engine running, but then after I started driving it and got fluid into the converter and everywhere else, it stopped. Was good for a few week and then dripped at least a half a quart on my shop floor in a week. Old gasket was the rigid Delco with grommets at the bolt holes, and I have a new one here ready to go in. Going to check the pan's bolting flange for straightness very carefully before I put it back together.

As for the spring, I guess I'm going to look up from the bottom and see if it's obvious where it came from. If not I may just bolt up the pan and hope for the best.

 

[yevgenievich]

spring looks like the one used in the park rod/lever assembly towards the back of the transmission. Helps return from park lock.(the lower of the two in the picture).
Mine is currently leaking from two places after sitting for a while. The pan it self and the harness connector. I have it limited to a reasonable leak rate and left it alone for now. If your pan is steel, I found that it does not work well with the rubber/metal style gasket if it is warped just a bit. I ended up using grey rtv style gasket maker. But because my connector is now leaking, I would have to redo the whole thing ago.

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[Daveo91Burb]

spring looks like the one used in the park rod/lever assembly towards the back of the transmission. Helps return from park lock.(the lower of the two in the picture).
Mine is currently leaking from two places after sitting for a while. The pan it self and the harness connector. I have it limited to a reasonable leak rate and left it alone for now. If your pan is steel, I found that it does not work well with the rubber/metal style gasket if it is warped just a bit. I ended up using grey rtv style gasket maker. But because my connector is now leaking, I would have to redo the whole thing ago.

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Awesome thanks. I’ll take a look at that park return spring. Seems like an easy fix if that’s it.

So on the pan, you use gray rtv only? No gasket? I always hear that those rigid oem gaskets are the best, but this is my second now so not sure about that. I know for sure I won’t use the rubber only one that came with filter.

 

[yevgenievich]

The best seal I have gotten so far was using the ultra gray rtv. But that is mainly due to a warped mating surface on the pan and wire wheel damage on the transmission side from previous owner. It is almost impossible to get the steel pan back strait if it has ever been overtightened before. If it is not straight, installing similar to how newer oil pans are installed seem to work best in my case.
I use a good 1mm or so layer, then install the pan watching for just a slight squeeze of rtv. Then let it cure and finally fully tighten.

 

[JoeR Jr]

You need to fix your leak, but the reason it drips after sitting is that it's not uncommon for the converters on a 4L80E to drain back into the pan when they sit. The pump bushings get worn and they don't hold fluid like they should. It's harmless, unless you have a leak!
By the way, if it drains enough that you have delayed drive engagement after sitting, let the truck run a minute before you drop it into gear. If not, you can set some trans codes that result is hard shifts.
I agree that it looks like the spring came off the parking pawl.
Joe

 

[Daveo91Burb]

Thanks guys. Good info on both. I'll be checking the park pawl spring and try to figure out the best seal. I may give the Delco gasket one more shot.....

 

[Daveo91Burb]

The best seal I have gotten so far was using the ultra gray rtv. But that is mainly due to a warped mating surface on the pan and wire wheel damage on the transmission side from previous owner. It is almost impossible to get the steel pan back strait if it has ever been overtightened before. If it is not straight, installing similar to how newer oil pans are installed seem to work best in my case.
I use a good 1mm or so layer, then install the pan watching for just a slight squeeze of rtv. Then let it cure and finally fully tighten.

Because of this I've been thinking about a new pan, but not sure that's feasible? After stopping at 2 parts stores today, one being Napa, and scrounging around on Rock Auto - seems like the OEM steel kind aren't available anymore? I'm guessing the pan design changed somewhere along the way. If I search for late 90s with 4L80e multiple show up, but for my '91 and even for a '94 K2500 nothing comes up. I did just find one on eBay that looks like it will fit, but it's description doesn't match up with my application.

 

[yevgenievich]

It looks like the only new pans available are the new style. It should still work, unless the cooling line location effects pan design

 

[Daveo91Burb]

It looks like the only new pans available are the new style. It should still work, unless the cooling line location effects pan design

Thanks. I took a look at mine and it's almost exactly the same as the one in the ebay listing I posted earlier. Some of those showing up on Rock Auto for later trucks show a ridge that I'd be worried would conflict with the filter. I think I'm going to buy the ebay one, seems like a fair price to me.

Having a new problem.... There's a bushing/gasket that goes between the machined hole and the filter's output that holds the filter snug. You can see it in my pic of the pan with fluid and old filter. Is that replaceable as a "filter gasket"? I don't remember replacing it when I changed filter last time, but it was at least a couple years ago. Rock auto shows a "filter gasket" but it looks like it's just rubber, not metal and rubber like in my pic.

 

[Daveo91Burb]

spring looks like the one used in the park rod/lever assembly towards the back of the transmission. Helps return from park lock.(the lower of the two in the picture).
Mine is currently leaking from two places after sitting for a while. The pan it self and the harness connector. I have it limited to a reasonable leak rate and left it alone for now. If your pan is steel, I found that it does not work well with the rubber/metal style gasket if it is warped just a bit. I ended up using grey rtv style gasket maker. But because my connector is now leaking, I would have to redo the whole thing ago.

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Yep, crawled under there tonight and it looks like that spring is missing from the park pawl assembly. Just going to find one close in length and spring constant and put it in there. Thanks.

 

[yevgenievich]

There is a filter seal in there. Some times they are a pain to get out. And factory one is harder composition than just rubber. Hard to see from the pictures. Usually new filter comes with new seal.

Thanks. I took a look at mine and it's almost exactly the same as the one in the ebay listing I posted earlier. Some of those showing up on Rock Auto for later trucks show a ridge that I'd be worried would conflict with the filter. I think I'm going to buy the ebay one, seems like a fair price to me.

Having a new problem.... There's a bushing/gasket that goes between the machined hole and the filter's output that holds the filter snug. You can see it in my pic of the pan with fluid and old filter. Is that replaceable as a "filter gasket"? I don't remember replacing it when I changed filter last time, but it was at least a couple years ago. Rock auto shows a "filter gasket" but it looks like it's just rubber, not metal and rubber like in my pic.

 

[Daveo91Burb]

There is a filter seal in there. Some times they are a pain to get out. And factory one is harder composition than just rubber. Hard to see from the pictures. Usually new filter comes with new seal.

Yeah, I feel dumb after my last post. There was a filter seal in the box - it was buried under the flimsy gasket that I won't use and hadn't taken out of the box yet. Seal even has the metal ring around it like the last one. Thanks.

 

[Dutch Rutter]

A little late I know but, best thing I have ever done to rid myself of transmission leaks was getting a lubelocker transmission pan gasket. Matched with an unbent pan and pan leaks are a thing of the past.