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7/6/15 1:44am - Original Message: 'Suburban A/T leaking around the pan'
daveo76
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Vancouver, WA - USA

Vette(s):
1976 Silver/Firethorn. L48, 4spd. Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.

Joined: 8/25/2005
Posts: 831
My 91 4wd suburban with a 4L80e is leaking around the pan - I can see seepage from the pan/transbody interface.  I just recently did a pan drop to try to solve the same issue, although now it seems to be worse.  Any thoughts?  I may have slightly overfilled it, but probably no more than 1/2 quart.  Is that enough for leakage from the top of the pan?  I used a fel-pro gasket that is installed dry - no silicone.  The instructions did call for some light grease on one side of the gasket but I assumed that was just to assist with placement so I did not do that (I just used some of the bolts to keep the gasket in place as I was installing the pan.)  Could that be my problem?  I torqued all the bolts in a criss-cross pattern.  

|UPDATED|7/5/2015 11:44:21 PM (AZT)|/UPDATED|


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1976 Silver/Firethorn.  L48, 4spd.  Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.
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7/6/15 6:01am - Reply: 'Re: Suburban A/T leaking around the pan'
johnu
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Eagan, MN - USA

Vette(s):
1981 Corvette Two-Tone Claret color, 4 spd, C7 Vert

Joined: 5/23/2007
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Grease is good.  Did you check the gasket surface on the pan with a straight edge to see if it was flat?

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7/6/15 6:20am - Reply: 'Re: Suburban A/T leaking around the pan'
Adams' Apple Lifetime Member
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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

Joined: 11/8/2003
Posts: 19454
Need to first determine if it IS the pan leaking. Check the selector(shifter linkage) shaft that sticks out of the ds of the trans, the filler tube seal, cooler lines, and the electrical connector....all of these places can leak, and seep around the pan, making it appear to be a pan gasket leak.
What type of gasket did you use? Cork, "farpack", black paper?


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Joel Adams
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7/7/15 1:22am - Reply: 'Re: Suburban A/T leaking around the pan'
daveo76
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Vancouver, WA - USA

Vette(s):
1976 Silver/Firethorn. L48, 4spd. Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.

Joined: 8/25/2005
Posts: 831
Thanks guys.  Joel, I double checked the stuff you mentioned and I'm 95% sure it's the pan gasket.  Entire driver's side is pretty dry - electrical connector and selector are dry.  On the passenger side there are the oil cooler lines (totally dry) and the dipstick/filler tube.  It could be the filler tube, but it does not look like it.  Worst case seeping is at front and back of tranny.  In fact, most is going on to the t-case skid plate and dripping through a hole in that.  At the front, it is dripping down the bell housing and falling off at it's low point.  The seeping is between the pan and the gasket, not the gasket and the tranny case which kind of tells me it is not coming from above?  

Not sure what material the gasket is.  Definitely not cork, pretty sure it's not paper.  What is farpack?  It's black and somewhat rigid.  Suggestions on what to use next time?  

I'm thinking another pan drop will be required.  I'm hoping to re-use the fluid - it's brand new and there are 6-7 quarts in there.  I'll use very clean containers.  The PO did one thing right and installed a drain plug in the pan - at least that makes things a little easier.  John, I inspected the sealing edge of the pan last time, but did not check it with a straight edge - lesson learned.  


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1976 Silver/Firethorn.  L48, 4spd.  Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.
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7/7/15 11:03am - Reply: 'Re: Suburban A/T leaking around the pan'
Vman73
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Gig Harbor, WA - USA

Vette(s):
1973 L82 4 Speed Coupe - Very original, well documented driver/survivor. 2016 Bend Regional NCRS Top Flight.

Joined: 10/2/2014
Posts: 362
Dave, not super familiar with '91 suburban tranny, but if it is a stamped steel pan, did you tap back the mounting holes with a ball peen hammer ??

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7/7/15 11:54am - Reply: 'Re: Suburban A/T leaking around the pan'
Adams' Apple Lifetime Member
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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

Joined: 11/8/2003
Posts: 19454
Sounds like a reusable gasket, Dave. Not many problems with those at all. Could have a buggered up spot on the pan somewhere I suppose....What of gasket did it have on it when you removed it the first time?

 



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Joel Adams
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7/8/15 9:52pm - Reply: 'Re: Suburban A/T leaking around the pan'
daveo76
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Vancouver, WA - USA

Vette(s):
1976 Silver/Firethorn. L48, 4spd. Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.

Joined: 8/25/2005
Posts: 831
Joel, I don't think it's a reusable one - it didn't have that bead of rubber or silicone or whatever.  But I did just order an ATP reusable from Amazon.  Guess what I'm doing this weekend???

Thanks!




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1976 Silver/Firethorn.  L48, 4spd.  Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.
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7/9/15 11:58am - Reply: 'Re: Suburban A/T leaking around the pan'
Adams' Apple Lifetime Member
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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

Joined: 11/8/2003
Posts: 19454
Most of the factory, and aftermarket reusable gaskets don't have the red/orange bead of rubber...most are all black. That just happened to be the pic I had. Reusable gaskets for the 4L80 are stiff. Actually rubber coated steel.
Cork gaskets are of course flimsy, and the Farpack gaskets are kinda in between...not stiff, but not floppy.
The pan rail itself doesn't have to be perfect....the gasket will fill in any minor defects. If the pan has any bent spots, or large dings, then you'll need to flatten it out as best you can. Check the surface of the trans well, too, for any gouges, or leftover gasket pieces.
You could get a later model(deeper) pan, and deep filter for it, too. The late/deep pans are made a little better(thicker steel), and have fewer issues with leakage. Thumbs Up


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Joel Adams
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7/12/15 12:58am - Reply: 'Re: Suburban A/T leaking around the pan'
daveo76
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Vancouver, WA - USA

Vette(s):
1976 Silver/Firethorn. L48, 4spd. Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.

Joined: 8/25/2005
Posts: 831
I got the ATP reusable pan gasket today - no instructions.  Assuming it goes on totally dry?  

So on a different note but same subject: the burb has not moved or run for over a week now and it's still dripping and seeping.  How can that be?  Did I really overfill it?  It was less than a 1/4" past full on the dipstick after I ran it in stop and go traffic on a hot day.  Maybe the dipstick is not seating properly and I'm putting enough in that the cold, static level is higher than the top of the pan?  Last time I drove it tranny was acting normal and shifting just fine.  


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1976 Silver/Firethorn.  L48, 4spd.  Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.
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7/12/15 9:20am - Reply: 'Re: Suburban A/T leaking around the pan'
Adams' Apple Lifetime Member
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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

Joined: 11/8/2003
Posts: 19454
ALL gaskets should be installed dry, with very few exceptions....imho. The re-usable gaskets can be installed with fluid on them, and they will still not leak, so they don't have to be perfectly dry when changing fluid, tho it is better to be clean & dry.

I'm bettin your leak/seep is something other than the pan, Dave, unless your pan is messed up. 1/4" overfull won't hurt anything, but it certainly can cause the fluid to spew out of the vent when it gets hot. Trans fluid expands as it gets hot, which is why there is a "Cold" and "Hot" marking on the dipping stick. Hot fluid should be in the middle, between the cold and hot limits. A little over is fine, as far as operating functions go.

My only suggestion is to use some brake cleaner, and spray the whole thing off...get it nice and clean. Drive it, let it sit overnight, and look for seepage/trails.



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Joel Adams
C3VR Lifetime Member #56    
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(click for Texas-sized view!)
             NCRS

"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
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7/14/15 1:27am - Reply: 'Re: Suburban A/T leaking around the pan'
daveo76
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Vancouver, WA - USA

Vette(s):
1976 Silver/Firethorn. L48, 4spd. Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.

Joined: 8/25/2005
Posts: 831
Well I drained and dropped the pan tonight.  Inspected the gasket I put in a few weeks ago - it's a flexible, black material, kind of like hard rubber, very thin.  (not much thicker than the rubber of a bicycle tire tube).  Inspected the pan and found a low spot on the bolting rim that is (what a surprise) right where I was seeing most of the seeping.  I lightly ball peened the rim in that area and got it to look a little better with a straight edge.  lightly peened some of the bolt holes that were slightly mushroomed, too.  Then installed pan with my new, reusable, much thicker, ATP gasket.  Also, the holes have grommets - on the old gasket the bolts fit in the holes very tight, I'm wondering if that could be some of my problem, too.  (gasket twisted a little as I was tightening bolts??)  Anyway, tomorrow I will fill it and test drive and hope for the best!  Thanks for the help.  

____________________________________

 

1976 Silver/Firethorn.  L48, 4spd.  Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.
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7/14/15 6:17am - Reply: 'Re: Suburban A/T leaking around the pan'
Adams' Apple Lifetime Member
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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

Joined: 11/8/2003
Posts: 19454
Ah yes....the cheesy inner tube gasket...LOL  Never seen one of those things actually work...too thin, and mooshy to seal anything. Add in a slightly disfigured pan surface, and you have a recipe for leakage.
The new gasket should fix it up nicely. Thumbs Up 

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Joel Adams
C3VR Lifetime Member #56    
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(click for Texas-sized view!)
             NCRS

"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
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7/16/15 12:47am - Reply: 'Re: Suburban A/T leaking around the pan'
daveo76
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Vancouver, WA - USA

Vette(s):
1976 Silver/Firethorn. L48, 4spd. Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.

Joined: 8/25/2005
Posts: 831
Go things put back together last night and drove it to work today - Knock on wood ....no seeping yet.  Time will tell.  Thanks again for the help.  

____________________________________

 

1976 Silver/Firethorn.  L48, 4spd.  Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.
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