tranny leak

[1966newport]

got my 68 300 out of storage today to find a large mess of red fuild on the floor. took 3 quarts to refill. tranny was professionally rebuilt in 2003 , about 10k miles ago. what should I be looking for?

 

[saforwardlook]

Such large leaks are usually from the selector shaft seal or the transmission pan gasket, but could be from the front pump seal too. The selector shaft seal will leave oil on the top side of the lower transmission housing on the ledge just above the pan. The trans pan gasket seal leaking will indicate wet fluid leaks around the bottom of the pan while a front pump seal will leak at the bottom of the front edge of the transmission housing, just below the torque converter. None of those leaks are ever much fun to fix unfortunately. The only other possible leak could come from the rear of the housing just ahead of the output shaft housing where it attaches to the main body of the transmission. There is a small O ring that seals the shaft that the kickdown bank rotates on, and sometimes an inexperienced transmission rebuilder will miss that seal because it isn't obvious that it is there until you see some fluid on the floor just above that area. So in short, check around carefully to see where the oil is originating and go from there. The only possible more simple fix would be to check the torque on the transmission pan bolts to be sure they are a little snug and not too loose. Generally after a transmission pan is installed during a rebuild, it is wise to recheck the bolt torques to make sure they are still uniform and snug, but not too tight either. After some driving after installing a fresh pan gasket, they tend to need to be retorqued after a little driving. So check those first.

 

[Big_John]

Could also be the dip stick tube o-ring.

If it' been sitting a long time, I'd drive it a bit and see how bad the leak is and figure it out from there. It might be a simple fix.

 

[saforwardlook]

Could also be the dip stick tube o-ring.

If it' been sitting a long time, I'd drive it a bit and see how bad the leak is and figure it out from there. It might be a simple fix.

Very true, but I have never had one of those leak yet. Just a sheltered life I guess!

 

[commando1]

And it never leaked before??

 

[BIGBARNEYCARS]

Real good information from Steve and John. I'll add my .02 on the pan gasket by only saying I've tried 'um all with and without adhesives and the only 727 pan gasket I'll ever use again is "REAL GASKET FROM TENNESSEE" Their customers include the air craft industry too if theirs any doubt the gaskets do what they say they do. Go on dry, torque to spec. DONE....And I don't give ah ratz a$$ if they're red or purple and do cost ah tad more, Jer

 

[azblackhemi]

If you drive the car regularly and the leak stops it probably is the shift shaft seal. After it sits for a few days the fluid drains back into the pan and will start leaking then due to the level being above the seal.

 

[saforwardlook]

If you drive the car regularly and the leak stops it probably is the shift shaft seal. After it sits for a few days the fluid drains back into the pan and will start leaking then due to the level being above the seal.

Just about every car I have has had the selector shaft seal replaced. The trans pan gasket comes in second. I just received one of those Real Gaskets for a pesky pan that I have had a real hard time to get to stop leaking, based on Jer's recommendation. I am going to try it out soon. I also noted that they have a new design that has recently surfaced that is a sandwiched type silicone gasket, with a middle layer that gives the gasket more support relative to resisting deforming that I might try next time too. It is relatively expensive at this point, but my view is that so is doing this job more than once and considering the cost of the tranny fluid that is lost each time the job is done.

 

[azblackhemi]

While we're on the subject of shift shaft seals here is a tool that makes it real easy to change them right in the car with out even having to pull the pan.

 

[BIGBARNEYCARS]

You'll like it Steve. Just follow the instructions that come with it. The new gasket you mention is the latest creation from Mother Mopar. Good but that one leaked on me too. A '62 727 transmission in my '61 behind the 440. 3 different gaskets with the original '62 pan glued and dry and it still leaked. New pan from Mancini Racing and 3 more gaskets glued and dry and same result, still leaked. Invested in a deep B&M aluminum pan. Hung it and noticed that it was 'bout 3" lower then the center link. Un-hung it and took it to a machine shop and had them carve 2 1/2"s horizontally out of the middle. Then took it to my favorite welder person and had him do his magic and run 2X360* beads inside and outside making it whole again. Then one more trip back to the machine shop for the final flattening of the mating surface on the bridgeport. Pretty red gasket (Made of Silicone BTW) Torq to 25 "lbs....NOOOOO MORE LEAKZ, Jer

 

[saforwardlook]

While we're on the subject of shift shaft seals here is a tool that makes it real easy to change them right in the car with out even having to pull the pan.

View attachment 55392

I have that tool Chris, but I still have a bit of a hard time getting it started into the top of the seal to pull it out in the car. Maybe the threads on mine are getting worn though, since it seems like it is harder to get it started than before.............................. Do you have a trick for putting enough downward force on the tool to get it started in the car?

I also still struggle with getting a new seal knocked in place - I use a friend down below to hold the installer while I tap it downward from the engine compartment above (near the brake booster) using a long extension and a medium hammer. It works, but much easier if the trans is out of the car. Then the whole job is cake. Maybe you have some better techniques.

Steve

 

[azblackhemi]

I use a flat body spoon to tap the remover tool into the old seal and also to tap the installer tool with the new seal. There isn't room to use a hammer but a flat bar that has a little weight to it works great.

 

[saforwardlook]

You'll like it Steve. Just follow the instructions that come with it. The new gasket you mention is the latest creation from Mother Mopar. Good but that one leaked on me too. A '62 727 transmission in my '61 behind the 440. 3 different gaskets with the original '62 pan glued and dry and it still leaked. New pan from Mancini Racing and 3 more gaskets glued and dry and same result, still leaked. Invested in a deep B&M aluminum pan. Hung it and noticed that it was 'bout 3" lower then the center link. Un-hung it and took it to a machine shop and had them carve 2 1/2"s horizontally out of the middle. Then took it to my favorite welder person and had him do his magic and run 2X360* beads inside and outside making it whole again. Then one more trip back to the machine shop for the final flattening of the mating surface on the bridgeport. Pretty red gasket (Made of Silicone BTW) Torq to 25 "lbs....NOOOOO MORE LEAKZ, Jer

So the red silicone sandwich gasket is made by ma mopar rather than Real gasket? From their insert flyer in the box the silicone seal they sent me was in (the one like the one you have been describing), they imply it is their design. I am aware of the sandwich seal design by ma mopar and have some of those I have yet to try, but I thought the latest red sandwich one is from Real gasket?

 

[Big_John]

Very true, but I have never had one of those leak yet. Just a sheltered life I guess!

My experience with the dip stick tube leaking has more than made up for none of yours leaking. A lot of my cars (including the present one) have had that issue.

 

[BIGBARNEYCARS]

The Real Gasket is NOT a sandwich Steve. The Mopar silicone sandwich I'm talking about is black silicone bonded in grooves around a dark brown hard plastic center? The Real Gasket is between an 1/8th" and 3/32nd" thick and is solid red silicone not a sandwich

 

[commando1]

How can anybody come up with all these solutions without asking more questions first.

 

[Big_John]

How can anybody come up with all these solutions without asking more questions first.

I have a handbook of standard answers that was given to me when I first got on the internet.

Included in that list are overheating questions that should always first be answered with "it's the thermostat" Starter questions are answered with "96 Dakota at the Pick and Pull". No start questions are answered with "ballast resistor and/or fuel pump rod".

In this case, turning to the trans leak section of our standard answer handbook, the proper response is "selector shaft seal".

As you can see, there is no need to ask other questions, all is covered in the handbook.

 

[commando1]

Lmao. Thanks John.

 

[1966newport]

it never leaked before

 

[saforwardlook]

The Real Gasket is NOT a sandwich Steve. The Mopar silicone sandwich I'm talking about is black silicone bonded in grooves around a dark brown hard plastic center? The Real Gasket is between an 1/8th" and 3/32nd" thick and is solid red silicone not a sandwich

Well, Jer, I have the black Chrysler gasket already and it is as you describe. And I have the Real red silicone gasket that you describe as well. But Real also sent me a sample of their just made available new type of sandwich gasket, and it has a stiff center and red silicone on both sides of it, probably to take care of the problems like Stan said he had with his Real silicone gasket (squishing out when tightening the bolts). So I'm not hallucinating - as it came in the same package as mother "Real" sent me their regular silicone gasket in that I ordered. They also said the newest type sandwich gasket was particularly better if reusing their gaskets in the future.