Two of my Cutlasses spent a decade or two sitting in storage, rarely if ever started or moved. Both are now back in driving condition and shift well when topped up with fluid, but leak copious quantities of transmission fluid if they sit for any length of time. One has pretty much bled itself dry.


I haven't gone looking for specific leak sources yet, but plan to pull the transmission from the '72 later this month for installation in my '70. Obviously I want to address the leak while I'm at it.


Is it typical for the gaskets to dry out and leak or is there likely a bigger problem? Is it just a matter of replacing a gasket or two? I'm assuming the pan gasket, maybe the speedometer cable seal need to be replaced...what else should I be expecting?


From what I can tell, the transmission is fairly low miles after some work on it including installation of a shift kit before it went into storage.

 

It's very common for gaskets to dry out. Also could be a seal. Try tightening the pan bolts just to see what happens.

 

If one of those leaks happens to be the front pump seal weeping & if it let's go while you are driving the car you will be spending lots of money to fix the trans. Ask me how I know......

 

I changed a pan gasket twice before I discovered that both the shifter seal and the kick down seal were the culprits.

 

The filler tube o-ring is another common leak spot. I've heard that when a car sits the torque converter can, or does, drain back into the trans causing a higher level in the pan, etc. So, someplace that may not leak in normal use, will leak because the trans is like overfilled when the car sits. I don't know if that's an old wive's tale or not.........

 

this is very true,no wives tale,the converter drains and effectively overfills the pan,when this happens it's usually the shaft seal or dipstick tube seal.

 

When I picked up my 70S it was low and topped it up 3 times on the 6 hour trip home. The last I threw stop leak in it but think somehow it slowed down some how. Do the front seal, maybe the pump bushing, pan gasket, filter, speedo seal, both of them and the tail housing oil ring, seal and bushing. The selector shaft can leak but I have only seen that on one trans.

 

You really need to go under and check. My car was sitting for years and leaking trans fluid. I changed the pan gasket,shifter seal and speedo o ring and was good to go.

 

X2...right...I really don't think there's a need to overhaul all the seals. The pan gasket, modulator seal, speedo seals (2), filler tube o-ring and shift shaft are usually the problem areas. Those are all pretty easy to do and cheap.

 

Mine was the kick down cable. Not the o-ring but the actual cable housing was cracked. After it sat for a few days the converter would drain back into the pan and fluid would leak out of the cracks in the cable housing. Apparently the cable was at lest partially filling with fluid.

 

Well, so much for a clear and easy answer to that! Thanks for everyone's input - as diverse the responses were, I think they've been helpful.


I'll probably start with a quick inspection of the transmission in the car to see if I can locate probable sources of leaking before giving the trans a good cleaning and refill with fluid...run the engine a bit and move the car around the yard a couple times, then let it sit again and wait for the drips to reveal themselves...and respond accordingly.


If the front seal is leaking, would it leak continuously even while running or only be intermittent once the converter has drained down?

 

Haven't done anything with it yet but I checked the trans fluid level last night (first time). Dipstick shows it as being exactly at the "Full" line, so it's obvious the torque converter drained down, appears that the seals below the normal full level are fine (or I would expect to see a lower level) and that the fluid escaped through the first convenient place above that line.


Based on that observation, I'm not planning to replace the pan gasket or other low seals. If this was your car, is there anything you'd replace regardless?


In regards to the torque converter leaking down, which seems to be hit and miss with the cars, would replacing the TC solve that issue or just be a bandaid? Obviously I would prefer to not have to run the car every couple of days while it's sleeping for the winters.

 

If it's not leaking don't fix it but did you get under the car and have a look?

 

It's not leaking now because the TC is empty . But it's lost a LOT of fluid over the past year of mostly not running, and that was obvious the last time I moved the car in the yard under power.


I haven't crawled under the car yet but that's happening in the next couple of nights. Just processing observations and thoughts as I get them so I can plan the work ahead.


If it isn't broken, I can probably fix it!

 

I've done some of my best work on things that weren't broken.��

 

I picked up front and rear seals to replace while the transmission's out of the car. I'll decide on any others once I can see clear indications of where it was leaking from.

 

I'd venture to guess that the speedometer cable is leaking for starters...

 

Ok, I've read all of the responses to your original question. First of all, I've been doing this for a long time. If a transmission sits idle for an extended period of time, the seals/gaskets can develop leaks. Fixing the first one that rears it's ugly head will only lead to the next, etc., etc. Since you are pulling the transmission out of the car, take the time to change all (3) seals/gasket on the front pump. There is the obvious front seal, where the torque convertor goes; but there is a large "O" ring around the outside of the front pump, as well as, a gasket between the front pump and the transmission case. Also, put a little RTV under each of the washers that are under the front pump bolts. Pull the transmission pan an look at what's inside. You may find that the trans needs freshening up. It's better to find out while it's out than going down the road. Any other seals can be replaced with the trans in the car, if you want a wait and see approach.

 

To be honest I've found that when a car sits it develops leaks that may be temporary. When the car is put back into service the seals will swell back out and leaks disappear. Once the car is started the converter fills back up, levels need to be checked with engine running and the trans at operating temp. I'd monitor it for awhile and run it regularly and see what happens. If your going to pull the transmissions refresh the one your going to keep, don't worry about the one your selling.

 

X2...I would agree with this. I've chased all those small leaks and fixed them. But if the car sits for 6-7 months,it might leak a little, sometimes. Then when I drive them, nothing for the 4 or 5 months I drive them.

 

I removed the dust cover a couple days ago and gave the whole transmission a good wiping down. The only signs of leakage I can see so far are the speedometer cable I mentioned a few days ago, and another near the dipstick tube although it looks to be coming more from the black cable. Is that the kickdown cable?

It will be a couple more days before the engine comes out but from what I'm seeing so far I think I'll stick to replacing the front and rear seals and addressing these two leaks.

What is that electrical connection/sensor beside the cable? I had a quick look and didn't see any obvious wires dangling around.

 

I didn't look at the pictures that you posted. I thought that you had a plug sticking up vertically on the driver's side, which would be for a lock-up convertor. The switch that is next to your detent cable is a ground for your TCS solenoid, that only allows vacuum advance in high gear. I would leave it disconnected.

 

Interesting. What time frame would it be correct for? Car is a '72, engine is a '71 and I was assuming the transmission belonged to one of those two years.

 

Also has me wondering if I should check what's in my '70 and perhaps avoid the lockup setup?

 

disregard; see above.

 

see above.

 

Whew! Thanks for clearing that up :-)