Friggin transmission leaks...

[Kern Dog]

I used to be a confident guy in terms of working on cars. I was a Chevy guy for many years and I had the support of the aftermarket to bolster my efforts. In 2000 I bought the Charger and had to develop my own support system to work things out.
I'm usually pretty decent at parts replacement. I can weld, do bodywork and paint. I've rebuilt engines and performed some minor transmission repair, but for some odd reason, the 727 in my Charger has really tested my abilities !
I had the trans out a month ago to modify the stall of the converter. After putting the trans back in I have had a pesky leak near the dipstick tube. I first thought that the pan gasket was damaged, so I replaced it with another Mopar plastic/rubber gasket. It still leaked. I tightened the bolts a little more. It still leaked. I pulled the dipstick tube and replace the O ring. It still leaks. I have headers and 1 inch torsion bars so getting a direct view of the origin of the leak isn't easy. I assume that the leak could still be from the dipstick tube, so I have one more idea that I read from a Moparts member. I'll drain the ATF, remove the pan and dipstick tube and clean everything. I'll smear sillcone inside the trans case where the dipstick tube fits, then smear some around the tube and O ring. I'll let it sit a day to set up, then put the pan back on and refill the ATF. If this doesn't fix the leak..... THEN what?

 

[mrkinger]

Join the leaky 727 transmission club,Welcome LOL

 

[67 coronet]

could be several things.a tiny crack is a common one.cork pan gaskets dont seem to seal well on these trans,so switch to a felpro black gasket if you dont have on already.i use the dipstick tubes from mancini racing.comes with a cup type seal rather then the oring.

 

[Kern Dog]

The cup seal sounds like a winner. I just was under the car and using a mirror, it appears that the leak is definitely from the dipstick area. I looked at another transmission and noticed that the tube presses into the trans case by 1 1/2". I marked my tube and will return to pull it out. My guess is that I didn't have the tube pressed in far enough.
I have had good luck with those plastic and rubber MOPAR trans pan gaskets.
The 727 in my 74 truck leaks at the KD and shifter seal. Where the heck do you find one of those???

 

[Citrus1973]

Shift shaft seal and kd can been had through rockauto.com

 

[Ron 73]

At one point in time i thought they were supposed to leak lol.. had more then one that did. These Mopars can and are ive found to be some real patience testers.. The cracked O-ring sounds a lot familiar and would start there myself if thats where its leaking. Good luck, there worth the extra head ackes once we get them right again..

 

[dfarmercse]

My 727 leaks, just haven't got under there to deal with it. Heck, everything leaks, rad: replace with 3 core. Front and rear seal, trans and a wheel cly. Soon as I get the inside finish, I am going to start fixing leaks.

Dave F

 

[dam130af]

Just means your tranny fluid is full. When it stops leaking is when you should worry!

 

[mrkinger]

I tryed everything to fix mine,no luck.it seems to have a mind of its own,So i decided to put a small peice of card board under mine and sleep good at night.

 

[Greg Ducato]

These dipsticks are often cracked just above the o-ring seat so when you remove the o-ring pay close attention to that area. The stock 727 steel pan is thin and easily distorted, especially after being overtorqued too many times. If you have a little patience and a good flat surface you can straighten out the pan and reverse dimple the pan bolts a little to help it seal. If you have the funds available, a move to the mopar deep pan or good aftermarket aluminum pan can help prevent future leaks. As some have mentioned, getting rid of the cork gasket is a good step. We like to use the Duraprene or Farpack gasket with a light coating of general spray adhesive on both sides. Another common leak spot on the 727 is the rear band lever pin. It has one or two o-rings on it and these shrink and create leaks at this point. These are difficult but not impossible to replace in the vehicle. I can hook you up with the selector shaft seals if you need them, we have a nice aftermarket slector seal that moves the sealing lip away from the original wear spot for a better seal.

 

[Garys1969RR]

Yea mine leaks too. Not alot. Replaced the shift shaft seal, but not the kickdown one yet. That did help. Doesn't appear to be the dip stick tube. Maybe the pan gasket itself? It is annoying, so I just throw a piece of plywood under there, too. Found a used 727 for $75, so will buy that, re seal the whole thing, adjust the bands and try it out. My old one starting to slip after a few hard runs. Gettin tired I think! That 451 its behind is really puttin it to the test! Good luck with your leak repairs.

 

[Kern Dog]

Thanks Gary. I may have sealed it up right this time. The RTV around the tube on both ends seems to have worked.

 

[ArtH]

Back in those "good old days" car manufacturers didn't care about small leaks from the engine or transmissions. My 77 Cordoba came with the original window sticker and warranty card.. 12/12 ..that's 12 months or 12,000 miles which ever came first and they were off the hook.

I think I finally solved the passenger side rocker cover oil leak that spilled a few drops of oil on the exhaust pipe and then smoked like hell when the engine starts. Aftermarket covers and the sticky rubber gaskets instead of cork. I recently received a note from the original owner who stated, "I always liked that car the only problems I ever had were oil leaks and carb." This gentleman has spent his most of his life with older cars and the notebook I found listed every thing he ever did to that car. Very meticulous. I think it's just the nature of the beast with these older cars.

 

[Sixer]

Care for a great leak detector tip? Clean suspect areas well with brake cleaner. Dry completely. Spray Arid Extra Dry or any aerosol Anti-Perspirant that is a powder form on suspect area-monitor carefully. You'll find it fast. And it'll smell fresh as a spring breeze to boot.

 

[Kern Dog]

I'm guessing that the anti-perspirant attracts and collects the leaked oil?
If so.....pretty clever!

 

[Kern Dog]

I have SOLVED the problem and willing to share the tricks!
First up, definitely use a Mopar O ring on the dipstick or a quality equivilant. Pull the pan off and clean the dipstick tube hole very, very well. Install the O ring and put the tube into the trans case. It should fit into the case a full 1 1/2 inches. The tube will extend below the pan rail by about 1/8". Smear Mopar RTV sealant around the dipstick tube from inside and outside the trans case. Let it dry, then attach pan and add fluid.
My trans now is totally free of leaks. I hope that this helps.

 

[moparphilip383]

Wow, I was told that is how Mopars mark their territory. This being the case I will have to try and fix mine.

 

[lyndondb]

Wow! Can't wait to try some of this. Had my 1969 coronet r/t since 1972 and it has always leaked, changed the pan, gasket, and dip stick. Still leaks.
Going to try the drain - clean the hole and rtv.

Thanks.

 

[AR67GTX]

My 727 leaks after I pulled the pan to fix the kickdown linkage at the valve body. After straightening the pan and two gasket changes I broke down and bought one of the new reproduction pans. Still leaks. Now I have a blue rubber coated gasket but haven't installed it yet. The one corner of the 727 pan that juts out and is kind of cantilivered is where I have problems. I finally cut a pan reinforcement out of 1/8 inch steel plate to fit inside the pan lip and is secured by the two nearest pan bolts. That seemed to help some but it's still a little wet.