We Have Ignition & Lift-Off

JED

Well Known Member
Supporting Member 5
After weeks (and weeks) of work to bring the ’34 Plymouth coupe hot rod back to life after its 21+ year slumber (does that make it a “barn find”?), I got to start and drive the coupe out of my shop and down the driveway today.

HURRAY!!

Now, I need to do some final checks for leaks, etc., get insurance and plates and it is a road car once again. As background, I originally built this car in 1974. It has a 350ci SBC, a TH350 trans and a '57 Chevy rear end. Originally I had a Corvair front suspension modified with a rack & pinion, but I updated it in 1995 with a Fatman Mustang II tubular front suspension. It was my only daily driver in the ‘90’s, taking me back and forth to work daily, as well as a couple of trips to Ohio from San Antonio for visits to my parents and the Street Rod Nationals. No updates were done at this time - only making certain that everything worked properly after a 21+ year slumber.

I can’t tell you how pleased I am that it is running again.092818-FirstStart-IMG_3453.JPG

John
 

JED

Well Known Member
Supporting Member 5
Transmission Question:

I realize it is not a "W" question, but I have a follow-up question related to my '34 Plymouth coupe. The short story is that I got it running and legally on the road again after almost 22 years of sitting. I took it to a rod run a couple of weeks ago and then put it back in the shop where it has been sitting for a couple of weeks. It has is 350/TH350 combo, all stock except for the intake & carb.

Twice now after sitting for a week or two, it has a pretty large trans fluid puddle under the car. Putting it on the lift, the trans pan gasket is wet but not dripping and the shifter shaft into the side of the trans is also wet. The first time, I drained the trans pan, removed the pan, worked the steel pan flanges to make certain that they were flat and replaced the pan gasket. I did NOT replace the shifter rod seal. I then added 2-1/2 qts of trans fluid per the service manual. When I checked the dipstick after the car was warmed up, it showed about 1/2 qt low, so I added another 1/2 qt more fluid. The car shifts fine and after a relatively long drive (15-20 miles), I rechecked the fluid level with the engine running and hot and all was ok. I then parked the car for a couple of weeks.

First week, I had no leaks and the trans level looked ok on the dip stick (checked cold and not running). By the end of the second week, I had a good puddle on both sides under the trans and the dip stick showed maybe 1-1/2 qt overfull (again checked cold and the engine off). Checking the trans on the lift - same problem. The pan gasket was wet on both sides and the shifter rod was also wet. Neither are dripping wet, just wet. There are no other leaks or drips and the torque convertor is dry on the outside.

My question is: Since I did not overfill the trans after the first time of changing the pan gasket, is it possible that the torque convertor is draining back into the pan over time (2 weeks) and overfilling the pan which would cause the leaking? I don't know how else to explain the 1-1/2 qt overfill. BTW, I drove it yesterday with it in that condition. It worked fine and the dipstick level read okay after driving 2-3 miles. Does anyone have any suggestions? If the torque convertor is draining back into the pan, what should I do about it or should I just ignore it?

Some photos of the coupe from 2 weeks ago. It cleaned up pretty well. That paint is lacquer that I did over 30 years ago (I have had the car since 1974). Everything except tires, starter, rear wheel cylinders, thermostat, hoses and fluids are just as they were when I parked it 22 years ago.

2018_10_12-CoupeFront.jpg2018_10_12-Coupe.jpg2018_10_12-CoupeEngine.jpg
 

La Hot Rods

Well Seasoned Member
Supporting Member 15
The torque converter is draining down into the pan, common if they set.
On some cases's you can double up the shift shaft seal to help there, on the kick down cable if you can use the cable with the sleeve type seal rater than the o'ring helps.
The dip stick seal can be upgraded to the sleeve type seal also.
Do stay away from the fancy braided stuff.
 

JED

Well Known Member
Supporting Member 5
Thanks. I have been watching the kick down cable & dip stick tube at the trans, but have not seen any leaks there. Everything I have on the trans are the original GM parts, although I chromed the OEM dipstick tube and trans pan years ago. I have never seen this before and know very little about auto transmissions. Has something gone bad that is now allowing the convertor to start draining back into the trans body over time?
 

61BUBBLE348

Well Known Member
Supporting Member 11
JED, I had an issue after about 10 years with my TH700R, started leaking and leaving a puddle, I put a new trans in the car a couple of years ago, what I found was the seal on the speedo gear drive housing had badly worn, leaked like a sieve. Seal cost a couple of bucks and no more leaks.

The seal is an internal seal inside the speedo gear housing. It may not be your problem, but it might be part of the problem.
Cheers
 

Junky

Well Known Member
Transmission Question:

I realize it is not a "W" question, but I have a follow-up question related to my '34 Plymouth coupe. The short story is that I got it running and legally on the road again after almost 22 years of sitting. I took it to a rod run a couple of weeks ago and then put it back in the shop where it has been sitting for a couple of weeks. It has is 350/TH350 combo, all stock except for the intake & carb.

Twice now after sitting for a week or two, it has a pretty large trans fluid puddle under the car. Putting it on the lift, the trans pan gasket is wet but not dripping and the shifter shaft into the side of the trans is also wet. The first time, I drained the trans pan, removed the pan, worked the steel pan flanges to make certain that they were flat and replaced the pan gasket. I did NOT replace the shifter rod seal. I then added 2-1/2 qts of trans fluid per the service manual. When I checked the dipstick after the car was warmed up, it showed about 1/2 qt low, so I added another 1/2 qt more fluid. The car shifts fine and after a relatively long drive (15-20 miles), I rechecked the fluid level with the engine running and hot and all was ok. I then parked the car for a couple of weeks.

First week, I had no leaks and the trans level looked ok on the dip stick (checked cold and not running). By the end of the second week, I had a good puddle on both sides under the trans and the dip stick showed maybe 1-1/2 qt overfull (again checked cold and the engine off). Checking the trans on the lift - same problem. The pan gasket was wet on both sides and the shifter rod was also wet. Neither are dripping wet, just wet. There are no other leaks or drips and the torque convertor is dry on the outside.

My question is: Since I did not overfill the trans after the first time of changing the pan gasket, is it possible that the torque convertor is draining back into the pan over time (2 weeks) and overfilling the pan which would cause the leaking? I don't know how else to explain the 1-1/2 qt overfill. BTW, I drove it yesterday with it in that condition. It worked fine and the dipstick level read okay after driving 2-3 miles. Does anyone have any suggestions? If the torque convertor is draining back into the pan, what should I do about it or should I just ignore it?

Some photos of the coupe from 2 weeks ago. It cleaned up pretty well. That paint is lacquer that I did over 30 years ago (I have had the car since 1974). Everything except tires, starter, rear wheel cylinders, thermostat, hoses and fluids are just as they were when I parked it 22 years ago.

View attachment 65662View attachment 65663View attachment 65664

Your car reminds me of my 1934 Dodge Pick Up I sold about 20 years ago. Yours is a great looking car. As for the transmission, how you check the oil in the transmission is sometimes the key to the problem. Some you would check the oil level with the engine running, and the car in park, and others like my '62 Powerglide, you check the transmission oil with the engine running, and the car in neutral. As was said, the torque converter will drain down, and flood the pan, pushing the oil out the overflow tube. I doubt that the shift linkage seal would leak that much, or even the pan gasket for that matter. Sometimes the pan gasket bolts that extend into the inside of the case will leak, because the oil will follow the threads down to the heads, but even that isn't going to give you a flooding condition. Using a sealant on the threads before you fill the transmission will stop that bolt problem, but the holes need to be clean and dry, as well as the bolts themselves, for the sealant to work.
 

bobs409

 
Administrator
As was said, the torque converter will drain down, and flood the pan, pushing the oil out the overflow tube.

We should put a surveillance camera on an old PG and see exactly where this leaks from! :D Then after it floods over, we just hit rewind to check the "evidence." :think I do like your idea of it probably coming out the overflow tube. Mine will fill a large drip pan easily!
 
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