Transmission Won't Move Car Until It Warms Up - PeachParts Mercedes-Benz Forum

Squiggle Dog · #1 09-21-2010, 05:00 PM

I've searched the forum for other posts and am still in the process of trying to figure this out, but in the meantime, I want to tell you about the problems I am having with my transmission and wonder if there is an obvious diagnosis.

I have a 1980 W116 300SD with automatic transmission equipped with a vacuum modulator. When I start the car and put it into drive the car does not move. I can rev the engine but the car does not move.

After the engine idles for about 5 minutes it feels like the transmission is starting to build up pressure and then the car is drivable, but it won't shift out of 2nd or 3rd gear (can't remember which but the car won't move above 20 MPH without the engine screaming). Finally after about another 5 minutes of slow driving it will shift into a higher gear. Then, for the rest of the day the transmission shifts perfectly throughout the gears and the shifts are hardly noticeable.

I don't know when the last time the ATF or filter were changed. The fluid is a little on the high side and the transmission leaks onto the driveway a little. I plan on going through the transmission and replacing parts. I will replace the ATF, filter, pan gasket, dipstick crush washers, cooler hoses, and possibly add Trans-X.

I have also considered replacing the pistons, spring kits, modulator, etc. but don't want to be wasting money replacing parts if it doesn't need them. Does the way the transmission is acting suggest one certain part has failed? I'm making a list of parts to buy. If I find out the answer I will post it here. Thanks.

Squiggle Dog · #2 09-21-2010, 05:30 PM

I'm still researching this and currently the plan is to replace the cooler hoses, filter, pan gasket, dipstick crush washers, then use cheap Dexron III ATF with Trans-X and see if this fixes things.

After a few hundred miles I'll replace the filter again and use Redline D4 ATF if the transmission is working properly. If not then I'll probably have to replace some parts, possibly the modulator or piston or spring kits.

If the transmission ends up needing to be rebuilt then I have a spare transmission that I can swap out.

I'm still interested to know if the transmission not functioning until the engine has run for 10 minutes is caused by a specific part failing.

4thesporty · #3 09-21-2010, 05:41 PM

Can't comment on your problem, but

A common source for leaks (as was in mine) is the hard cooler lines where they have clips that secure them to the motor oil pan. There is a little bushing that wears out, then the line rubs on the metal clip and eventually develops a leak. I sourced some from the junkyard and cleaned them really well and somehow got them in there.(they are a pain to fish through.)

Squiggle Dog · #4 09-21-2010, 08:57 PM

I think I have ruled out the vacuum system and modulator being bad since the transmission shifts beautifully once it's warmed up.

I don't think a K1 spring or B2 piston kit would fix the problem as once again, once the transmission warms up it works beautifully.

A filter and fluid change might help it work slightly better, but I am thinking it won't fix the problem.

After lots of reading I am thinking that maybe the internal seals are hardened which may cause a loss of pressure until the fluid is warmed and the seals expand. Trans-X might condition the seals and help with this. It also might loosen up sticking valves, which could also be the problem.

Or, more likely, I am thinking that the front pump may be weak and it takes a while for it to build up enough pressure to move the car. If so, I am going to have to replace the transmission with my spare or just swap out the front pump.

In any case, I think I have come to the conclusion that at this point a new modulator, K1 spring, and B2 kit would be a waste of money and would not fix the problem. A filter and fluid change followed by Trans-X would be worth a shot. Who knows, I may be able to get by for a few months on a weak front pump if this is the case.

I think I'll disconnect one of the cooler hoses at the radiator and turn on the engine to see if the pump is pumping any fluid out of the hose when the car is cold. If it's a weak stream (or no flow at all) then at least I will know the pump is going out. If there is good pressure then it's probably internal seals or sticking parts. I'll loose some fluid, which will be good because I think it's an inch above the full mark anyway and I'll need to add Trans-X.

I might do the Trans-X thing before I change the fluid and filter (filter kits are around $50, ouch). So is ATF. I'll probably keep the current fluid and filter in there and run the Trans-X for a couple hundred miles. If the problem fixes itself then I will change the fluid and filter and if not, then I'll get ready to swap transmissions or pumps.

Another thing is that this car had been setting for months before I bought it and I have had it parked for months and only had it running long enough to move it in and out of the driveway, so maybe the car just needs to be run.

The spare transmission and torque converter I have is from a 1979 W116 300SD. It was rebuilt 19 years ago and has 100,000 miles on it. The metal flex disc on the flexplate shattered and the fragments chewed up the inside of the bellhousing and scraped up the torque converter. I don't think the metal particles got inside the torque converter or transmission. I just don't know if the torque converter was thrown off of balance since some small chunks were taken out of it. I hope not if I need to use it if the torque converter on the 1980 ends up being bad.

babymog · #5 09-21-2010, 09:01 PM

Internal seals like you mentioned, somewhat common on older automatic transmissions.

Squiggle Dog · #6 09-21-2010, 10:14 PM

Quote:

Originally Posted by babymog

Internal seals like you mentioned, somewhat common on older automatic transmissions.

Yeah, and maybe the Trans-X will help it limp by for a while. The car has over 300,000 miles and I have almost no records or receipts for the vehicle. I believe the factory service manual states that the transmission must be removed with the engine and the way the bolts are recessed I think it may be correct. However, maybe I can tilt the engine back enough to access the recessed bolts...

loepke72 · #7 09-22-2010, 08:18 AM

+1 on internal seals. Expect to find burnt clutches and/or bands if the car has been driven like this any significant time.

Not 100% sure about the diesel 116, but I have removed the transmission on the 450SEL by itself leaving the engine in the car. If anything I would think the diesel would be even easier in this regard. Of course I had the advantage of using a lift when I did this. You'll just need to use long extensions to get to the topmost bolts with the rear of the transmission lowered.

layback40 · #8 09-22-2010, 08:26 AM

with a w123 you can lower the trans so tilting the motor. this will allow you to remove the bell housing bolts with a very long extension on a socket.
remove the torque converter with the trans by removing the bolts that hold it to the flex disk/ring gear. Its much less work to remove the trans from underneath than pull the motor/trans together.

Squiggle Dog · #9 09-22-2010, 05:06 PM

Wow, so far the consensus is internal seals! I'm glad we're in agreement. I'll try Trans-X additive and see if it softens and expands the seals enough to get me by until I can do the transmission swap (if it gets me through until next summer I will be ecstatic!). If the Trans-X doesn't work then I don't think there is anything else I can do but replace the transmission.

babymog · #10 09-22-2010, 05:09 PM

I'd try the Trans-X also. Any external leaks?

Squiggle Dog · #11 09-22-2010, 05:23 PM

Quote:

Originally Posted by babymog

I'd try the Trans-X also. Any external leaks?

It was leaking a bit when I got the car but the pan bolts and dipstick bolt were loose so I tightened them and now it only seeps.

If the Trans-X works then I'll do a fluid and filter change, then if the problem returns, I'll add more Trans-X. If the Trans-X does nothing then I'll limp around on the transmission for a while until I can put in the spare.

The rainy season is coming upon me here, but I do have access to rent a lift and tools at work for $25 a day, so I might drive the car there and then do the swap. It would be much easier to do it with the car in the air and out of the weather.

I think the spare transmission will work great since it has only 19 years and 100,000 miles on it, just as long as no broken chunks of flex disc entered it or the torque converter (but I doubt it as it the particles would have had to enter through the front seal).

Squiggle Dog · #12 10-01-2010, 05:39 PM

The transmission was a little less than a quart low on the dipstick so I added a 15 oz can of K&W Trans-X. I've been driving the car daily for a week since then and the functionality of the transmission is improving!

The car now only has to idle for about 1 minute in the morning before I can drive off and it's not sticking in low gears anymore. When I drive home from work I can drive off shortly after starting and the car shifts properly.

If the transmission keeps improving then I'll plan on doing a fluid and filter change with good Redline D4 ATF and add Trans-X if it starts to act up again. Then I'll use the transmission until it's completely worn out.

Fattyman · #13 10-01-2010, 07:04 PM

All in all a much easier than putting that 5 speed in it.

biopete · #14 10-01-2010, 09:33 PM

Quote:

Originally Posted by 4thesporty

Can't comment on your problem, but

A common source for leaks (as was in mine) is the hard cooler lines where they have clips that secure them to the motor oil pan. There is a little bushing that wears out, then the line rubs on the metal clip and eventually develops a leak. I sourced some from the junkyard and cleaned them really well and somehow got them in there.(they are a pain to fish through.)

That's how i got my last 1985 300D for 250.00. The mechanic thought it was a transmission seal and was going to be a lot of work. It was just that the metal clamp wore a hole in the metal line. A 3-inch piece of fuel hose and some hose clamps fixed it good. 50,000 miles later and several trips around the country and that patch has still held.

richland007 · #15 11-19-2010, 12:15 AM

Hi there my 1991 MB 300D 2.5 Turbo Diesel (nicely restored and running on a Grease King WVO kit) got hit by exactly the same problem a couple of days ago. I started the car and did not wait long enough for it to warm up and took of after just a minute or 2 running worked perfectly until i got to a red light right outside my house at the corner after i stopped at the light the car would no longer move. Not on 2 not on 3 not on D not even after it warmed up or any longer. I should say that the car has never suffered from transmission issues at all it was driving like a good solid diesel with the turbo kicking in and shifting nicely for the past 2 years that i have owned it. I opened the transmision fluid pan to perform a ATF change and change the filter and add trans-x to it and it is still open because i found the attached peace floating in the transmission fluid. its a perfectly smooth round cylinder with round heads at the end with one side slightly bigger than the other. It looks like it has come out of somewhere there but i don't know where has any one have similar issues like this and does any one knows where that peace goes in the transmission? please review the pic and let me know any help is greatly appreciated
thank you
Denis

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