My truck: '92 1-ton, 4WD, 6.5TD, HD trans. Bought it 10 months ago for $4,500 with 160K on odometer. Nice all around truck; runs perfectly. I changed all fluids over the first 2,000 miles I had it: difs, auto trans (including pan drop, filter and complete fluid change), brake fluids, etc. Truck was always dry underneath when I got it. Same after all the work.....for another 3,000 miles. Then I developed a trans fluid leak that appears to be the pan gasket. Was back at shop that did work and they snugged bolts; but it is now worse. Truck has been sitting for 3 weeks inside and still slow drip, even when it's not just hot-off-the-road. They suggested I might have torque converter seal leak, but I only see wet areas around the trans bottom pan gasket. Before trans service work, fluid smelled good and was very clean. Not like I had them change dirty, really old fluid.

So I figure, "do the simple first," and change the danged pan gasket again. Never done one, but truck being 4WD, I can slide under it without even jacking it up. All bolts (10mm, I think) are potentially fragile as their size is only about that of a quarter-inch bolt and I suspect they can break easily. I searched the archives here and see there is debate between cork and neoprene gasket material. 25-pounds torque on tighten I don't know whether to go to NAPA and see what they have or go directly to Chev dealer for gasket. Some say use gasket sealer, some not. I am thinking of pulling pan, checking for gasket-area, "straight-ness," then using a little sealer on the pan side. Not sure about trans casting side. I don't see any hidden pan bolts right off, but do see some front and rear that require a universal joint socket.

One fellow said replace the gasket with a little sealer and do not put fluid in for a couple days until sealer cures. Might be good idea unless internal seals in trans dry out !!!!!! (thoughts?)

Any tips for my first pan gasket change out?? Any surprises dropping one??

Thanks, Dennis...a bit nervous....

I like the rubber gaskets myself. Make sure the torque is Inch #'s or Foot #'s (lots of difference there), I usually use a 1/4" ratchet gripped in the palm of my hand and just snug them up good. Make sure your dipstick tube and tv cable o'rings aren't leaking (can look like it's coming from the pan gasket). Check shifter shaft seal also.

Ive always cleaned the pan very well with brake cleaner. Once I do that I take the pan and put a thin layer of RTV on the pan only were the gasket will be. I then take the gasket place it on the pan. After that I put something on top the pan to hold the gasket firmly in place. I let it air dry for about 15 minutes. After that I put a layer of RTV on top the gasket then again let it air dry about 15 minutes. Make sure you have no leaks and drips from the trans. As the gasket sets up on the last rtv treatment i change my filter on the tranny. I always use a 1/4 drive in hand and turn all bolts tight as I can by hand without using the racthet. After that i follow up with a torque wrench tighten them all evenly. By letting the RTV set up a little you eliminate the gasket moving around. This methoed has worked perfect for me for years with NO leaks. Also I like CORK gaskets on trannies.

Ahhh. Thanks. This helps.

Dually....you said that during the application of gasket sealer, "..make sure there are no drips or leaks from trans..." At that point, with pan down, wouldn't the trans be dripping occasionally from up in the various wet chambers of the transmission anyway? Or am I missing something?

Krue, ...hate to ask this but, what's the, "tv cable?" Really good points on o-rings, etc. I did have a major leak from that once in an old car....pressed right in, easy fix.

Sounds like I might benefit from sliding under the truck, blasting all the ATF off the trans bottom, then going back under twice a day with a good light and watching. I wonder if I can see all the leak possibilities from underneath.

Dennis

I do the same. Clean very well with brake cleaner. Then I always use "finger film" of sealer. By that I mean run a small bead around then spread it evenly with your finger all over the flange. And make sure that your bolt holes have not been tightened down to where they are protruding on the transmission side. Take a small ballpein hammer, put the ball part into the hole and strike it with another hammer back towards the outside (road side) This will insure that the pan holes are not interffering with the gasket.

Kevin

TV is the throttle valve cable, yours may not have it, if it does it will be right by the dipstick tube.

kelvin45 hit it on the head. you said you re-tightened the bolt. make sure you follow kelven45s advice.

overtightening the pan bolts is the most common cause of leaks. Can't remember the torque spec, but it is very small. I usually use a small amount of rtv on both sides of gasket and allow it to cure maybe an hour before adding fluid. If it is cold, let it cure longer. For the rubber gaskets, rtv is not needed but helps to put a little on the pan to hold the gasket in place when mounting.

Well, I guess I came here to learn, and I am. I think you are all right once I think it over. I've never had the trans pan in my hands so I don't know how heavy a material it is made from, but now I'm thinking it is like a rocker cover. I think I understand that Kelvin45 is saying the pan holes themselves become distorted during overtightening and the metal gets mushroomed upwards toward the trans. So that would be metal interference allowing a pathway for leaks that increases the more the mushrooming occurs.

Right? Again, like a rocker cover.

Wonder if there is a good way to drop the pan without getting covered with ATF? ha. Not sure how effective it would be to try to suck it out through the dipstick tube.

Dennis

leave 3 or so bolts in loose- just a couple threads- and bump 1 end with a rubber mallet to release a corner or end, it will still be messy, but most will hit a drain pan.
Yes, the pan is rather thin stamped sheet, like a stamped velve cover, and easily distorts. I try to use a nitdriver handle and snug the bolts only, this is usually abought right in torque.
Also, the bolt sequence is debatable, but a head gasket stly pattern is prolly best to evenly distribute the force and not roll the gasket and put a bulge in it somewhere.
Good lick

Might be a good time to install a drain plug. You can get a kit from most auto parts store. I got mine at Oreilly's it was on the rack with carb spacers and dressup kits.

oh, i meant good luck!