Transmission leaks like a sieve, but only when hot
 

Hello folks,

I just got my 300D back yesterday, and decided to drive it to work this morning. I noticed that when I picked it up, that the shifts where early and abrupt, but I figured this was merely either an adjustment to the bowden cable and/or the modulator.
Everything went fine until I was about 5 minutes off the freeway... I noticed slipping... 1/2 mile later, while at a left hand turn lane, there was no movement whatsoever! First thought was that possibly a line was broken and it just bled all over the road. I happen to look behind the car, and noticed a large puddle of tranny fluid. Then, I looked under the car, and it was almost literally running out ot the tranny ( passenger side ). So, naturally I thought that the pan was loose. Seeing as how I was in the left hand turn lane at a very busy intersection, I decided to see if I couldn't get at least some movement of out it. (pushing was out of the question, the intersection was waaaay to big.) It made it across the intersection. The road there was on an incline, so i decided to coast. A phonecall to work, and within 10 minutes I had some quarts of fluid in my hands.
After adding a generous amount, I got back into the car, and took off...everything was as it was when I left my house earlier.
I took the car out for lunch, (I'm the one that ate, not the car :D) -everyting was fine. My trip home consists of about 20-30 minutes on the expressway - shortly after getting to a normal road, and having to stop at a light, the slippage was back! I pulled into a service road, and had a look-see. Again, fluid leaking out in little streams. I had a huge migraine, and decided to go to the drugstore a few hundred feet away. After returning to the car maybe 10 minutes or less later, I got back in it and was able to continue driving as if nothing was wrong. ( go figure ) This time I was going to not go home, but to the mechanic who installed the rebuilt engine and also put in a new filter, along with a front seal. ( the modulator valve was either replaced then, or is quite new) I was just about there-all I had to do was make a left turn and into a driveway, when it started its slipping thing again- I made it by the skin of my teeth, and idled up his driveway. Looking under the car, little streams where once again visible. After sitting there for about an hour, he had a lift free and up in the air it went. He cleaned the area and tried to see where the leak might have been coming from. Nothing Then he decided to turn onthe motor and engage the trans. He looked again... and again... Nothing.
This for me is really weird. :confused:
Why would it only decide to leak like crazy once it was hot? Does this mean I have to move to Alaska? Is my transmission possessed and in need of an exorcism? :eek:

Any input is greatly appreciated! :)

-Larry

Hi Larry;
You are the second one with this Ghostly problem in last 7 days.
I dont know whats going on here??? Look at one of the other posts in last few days about leaking Tranny.

Did you change the gasket lately?? And if yes where did you get it from and which brand? I think there are some bad generic gaskets out there??

MVK

Larry, from what you are telling us, it seems that the front seal he installed was put in incorrectly. Did the mechanic fill the trans when you coasted in to the shop?? If he did the leak will definetely show up again. I wouldn't let that car out of that shop until you are sure he fixed the leak. It's really not a good idea to drive the car until you are sure its repaired. There is one thing that automatic transmissions really hate and that is running dry. It does very nasty things to the clutch packs! Let us know what you find!!

MVK & Bill

Yes, I did see that post about the leaking gasket. What I think differentiates our two problems, is that this leak doesnt occur until the trans is hot. I could probably drive several hundred miles without trouble, but, as soon as I got off the highway, I would bet $$ that within 3 miles, it would start to drizzle oil again.

I'm thinking that if the pan gasket, and/or the seal was not correctly installed, that I would have more immediately occuring events.

Thanks for the reply :)

-Larry

I'm the guy with the same problem. Mine also does not leak unless it is hot. I was thinking it is pressure related.

I would have to drive about three miles before it would leak, and when it does leak, you can pour more fluid into the filler tube and it will pour right back out.

I am out of time to work on this problem and am going to drop the car off at the local MB dealer to fix. I will tell him not to give it back to me until it has been tested.

I will then talk to the mechanic to find out what he did to get this thing to seal. I can only think now that the seal is slightly thinner.

The transmission could be overfilled, this is as bad or worse than too little fluid. And I would guess the fluid would expand and leak out when hot.

I had a problem with the front seal and clutch soon after I bought my car (driven maybe 300 miles), but it happened with the transmission cold (just started the car in the morning) and was an expensive but effective fix by my mechanic. I suspect installation error caused the first problem.

Both my friends with leaking gasket:
Just a thought. I hope you guys are not overfilled. When I did mine at home, then filled per the specs, it was overfilled. I had to darin out some.
Check when its full cold, the level should be slightly below the lower mark, then check as specified when hot, it should be between the marks.

Still beats the hell out of me as to whats up with your tranny??

MVK

B2 piston seal? Upper passenger side, no pressure in it in fourth, but there is at low speed in other gears.

I've seen a similar problem with the low/revers band servo on Borg Warner (Ford) automatics -- blows fluid like crazy hot while stopped since the servo is pressurized in 1st or reverse, usually doesn't leak as much cold, seal on the cover shot. Leak stops once the pressure is off the servo. It leaves a diagnostic trail -- puddle under the car when you stop and a trail until the car shifts into second, then a few drips. On the MB, it might start after the car moves off, the stop when it changes gear.

Peter

Michael,

I am waiting for the results of your trip to local MB dealer with baited breath.

-Larry

Just got back from vacation and picked up the car.

Dealer says the tranny was overfilled by 2 quarts! I hope I did no permanent damage to the trans.

Now, the book says (owners manual) that a refill without draining the converter is 5.5 liters. I put in 5 quarts which is less than 5 liters and I was 2 quarts over. The manual must be wrong!

Car runs fine now, but looking at the invoice, they (the dealer) charged me for 7 quarts, so I'm guessing they drained the torque converter. I'll try to talk to the mechanic who did the work tomorrow as he was out to lunch when I was there.

I have always filled an automatic tranny by putting a couple quarts in (usually a little over half the required amount) with the engine off, and then added more with the engine running, checking frequently, until I had some on the bottom of the stick. Best the cycle through all the shifter positions a couple times, too, before adding extra. Then I get it hot by driving some (1.5 miles, usually, which is around the "block" for me-- actually a triangle), then checking hot. I'd rather take extra time than get too much in, as it will get into the gear train if it is too high, foam, and blow out the vent, plus the foamed oil will cause the clutches to slip, etc.

This, by the way, is what happens to overheated trannys when someone tows something much too large -- the viscosity drops with heat, the oil expands, gets into the gears and gets foamed, blows out, and the clutches fry.

I don't think you can do serious damage unless you are really driving hard -- if the fluid doesn't smell burned you are probably fine.

Peter

Update
 

I ordered a new gasket, thinking that this might solve the problem. Today I drained the fluid... and thats when I saw that what should be red and clear, was pink and cloudy!
Arrgh. :(
My conclusion is that the tranmission cooler ( the one thats inside of the radiator ) has a hole. Once I was off the freeway, the engine temp went up, the pressure increased, and pressureised the transmission, forcing fluid past the pan gasket.
That, is what I think is wrong.

Now I need to decide what to do....Do I buy a new radiatior, or do I see about buying a trans. cooler and plugging the lines at the bottom of the radiator?

Any comments, ideas, suggestions, or even a good joke, are appreciated :)

thanks!
-Larry

Oh boy:
Sorry to hear the bad news. Hopefully the mixture did not mess up the tranny.
Now about the tranny cooler, I had one large size put in my Oldsmobile in series with the radiator. I was getting that at a bargain price from a friend so I decided to attach that one. Yes it worked well and tranny ran much smoother. Then again GM olds tranny are like best shifting ones in the industry.

You can try one but in my opinion what prevents the radiator from going bad at other places. So why take a chance. I would put a new radiator and a midium size tranny cooler -IF YOUR TRANNY HAS A PROBLEM OF RUNNING HOT. Otherwise just a new radiator should be fine.

MVK

An external cooler can over-cool the transmission, not a problem in Florida, maybe, but surely would be up here.

You cannot replace the cooler in the rad, alas, since it requires removing the cold side tank. This isn't a problem, but getting the rad back together most certainly is. You will only trade a leaking tranny cooler for a leaking rad.

Bite the bullet and get a new rad. You will thusly be spared the broken upper hose nipple and obligatory cracked head. $300, easy to install. Put new hoses on at the same time.

Peter

Replaced my radiator a year ago with OE for ~$200. Easy to do, id it as preventative maintenance. Mine was developing a hair-line crack along the palstic top piece. Made my car consistently run at exactly 100deg C.

As for filling the tranny, I always measure the amout that I took out first, and measure that same amount back into the trans to start; then drove a while and rechecked etc. I have found that it's too hard to guess what's the right amount to use, even if it reads full when running.

The transmission fluid level will rise significantly when the transmission is at opperating temp (20+mi driving), so go for a long drive with both a quart of tranny fluid and a vacuum pump w/ reservoir. Once you get it right, always measure first before filling (as long as it doesn't leak, the fluid should be the same level no-matter how long it's there; unless you have other problems).

ATLD

P.S> Now, why they don't measure transmission fluid amounts w/o the engine running is because themperature expansion is quite significant in that specific fluid, so if you lived in maine and filled the trans, you have more fluid that someone filling that transmission in Florida (considering ambient temperature was the same as the trans fluid temp). By driving the car and heating up the tranny, all the cars should get the tranny to about the same temperature. That's why you must drive...and drive...and check... and drive. The transmission fluid leve is much more sensative than any other fluid level in the car to temperature expansion.