Any tips to guarantee a leak free trans pan?

[WH23G3G]

Ok I haven't had motovation to even work on my 73 in so long because of the continuing leaking problems. Well now I have some time on the weeked to tackle it once again. Remember I had so much trouble with leaking valve covers especially the passenger side. Well after too many attempts I got the passenger side sealed (I think so far) but the driver's side which I originally didn't suspect a leak at is leaking worse than the passenger side ever was. So that's when I just gave for awhile but now I'm going to attempt to fix it. It still has those Mopar orange silicone gaskets on the driver's side. I bought the metal reinforced for the passenger side and that's what seems to have stopped as far as I can tell. So I was just going to change the driver's side over now and hopefully it will stop. But I don't ever know I could drive it down the street and they could start leaking again. I also have a transmission pan leaking. It's a new chrome pan but there's no plating on the flange. I think the bolt holes on the gasket were so tight that when I installed the bolts into the pan it may have moved the gasket eventhough I glued it to the pan using the spray adhesive. This will also be my third gasket on the transmission pan. Twice on the original pan and now once on the new pan. Any tips to guarantee a leak free pan for sure? I still haven't gotten to actually drive it down the road either because of the leaks. So I want them to stop so I can.

[John_Kunkel]

Are you absolutely sure the pan gasket is the source of the leak? Many leaks that originate above the gasket will run down to the protruding gasket before dripping off giving the gasket the appearance of leaking. One often overlooked leak source is the end of the rear band pivot lever, it is just above the pan rail and hard to see.

If the gasket is the problem, the current factory gasket is the best there is...install it dry to clean/straight surfaces.

[WH23G3G]

Yeah thats what I thought too, But it is definitely the gasket, you can see it coming from around the rail and everywhere else on the entire transmission is bone dry, the filler tube o-ring, the pivot levers, the speedometer ring, and the shaft seal, and pump seal area all dry.

[charger Downunder]

Make sure the pan gasket surface is straight and don"t over tighten the bolts and squash the gasket out. I torque mine up by hand (feel). Drive around, once hot nip them up just a bit by hand.

[Kern Dog]

I have no way of knowing what model that your 73 is.   A Dart. A D 100 truck. A Plymouth Cricket.... A slant six valiant.....
If it is a 727 trans in whatever you have, the Mopar 518 gasket is a great piece. Its hard plastic with imprinted rubber. If IT leaks, the problem is elsewhere.

[y3chargerrt]

Get a good quality rubber pan gasket. Make sure everthing is clean and the pan rails are flat. Spray both sides of the gasket with hi tack. Allow to get tacky. Position it on the pan then bolt up. Do not over tighten. Take a test drive then retorgue.This has never failed for me.

[Plumcrazy]

Go to a Chrysler dealer and get one of the reusable rubber coated  transmission pan gaskets.
Like JK says,they are the best.

You'll need to know if you have a 904 or 727 transmission.

[WH23G3G]

Mine is a 73 Charger 400 w/ 727. So they make a thick reuseable gasket? What do I tell the Chrysler dealer it's for? When I come in telling them it's for something old they always tell me they can't help me. I see you said a 518 transmission has that type of gasket. Is the pan shape the same too? Are they very expensive?

[Kern Dog]

There are plenty of idiot parts counter guys that only understand what the book or computer shows. Research is too difficult for them.
The 518 shares the same pan pattern as the 727, but the 518 uses a deeper unit.

[WH23G3G]

Well I still would probably have to get the gasket through Chrysler because the ones at the part store would be just generic rubber or say the OEM gasket is reuseable.

[GPULLER]

Go to the dealer and get a reusable gasket for a Ram pickup they used the same gasket as a 727.   P/N 2464324AC retail of around $15.60  Those gaskets are a hard plastic with silicone bead on both sides to seal.  No sealer is needed on the gasket.  The hard plastic prevents over tightening the pan bolts and possibly causing the gasket to squish.
Make sure your pan flange is flat, or you could buy a new Mopar Performance deep steel pan.  The hold a couple extra quarts of fluid and have a drain plug.  The are pretty reasonably priced.
I had many problems with getting my trans to seal.  I went with a new MP pan and the stock Ram gasket and no leaks.  Highly recommended upgrade.