Transmission slips when it's cold

[Elyaouti800]

Help! I have a 1984 Mercedes DT transmission has 400,000 miles on it. I know; it’s awful in the snow!

Everything works well except that the automatic transmission sticks in cold weather (50 degrees or colder). I have to drive the car 1 or 2 miles before it will shift into a higher gear. It gets really bad in 30 degree weather or cooler. Also what I've noticed is the temperature gauge no longer goes up to 80 it stays just below it. I think the thermostat is going bad?

This slipping just started happening recently. It happened before only until I change the filter and Gasket and put in new fluid it started shifting well. If anyone can give me some insight on what it could be I've already changed the fluid filter and Gasket. Thanks

[oldsinner111]

vacumm could be trouble too.unhood line from trans, and block other port. This will cause the trans to shift harder,but not slip,until you can trace leaks.These cars are good in the snow with snow tires,and a extra 150 pounds in the trunk

[jake12tech]

Worn clutch packs will slip when it’s cold.

[vwnate1]

When the tranny in my '82 240D was going, a member here suggested "Trans-X", I schlepped down to my FLAPS and they had multiple choices of this product, I tried the yellow bottle and added some, Lo ! . the tranny began to shift properly again and the ATF leak subsided too .

I was able to nurse another few years and 40,000 miles out of it before having the tranny rebuilt .

I did have to add more of this product occasionally .

Hopefully you drained the torque converter when you did the fluid and filter ? .

[Diseasel300]

Is it actually slipping, or is it just staying stuck in a lower gear? Your description sounds like the latter rather than the former.

Make sure you have the correct amount of fluid in there, check with trans at operating temperature and engine running. Low fluid level can cause all sorts of weird behavior.

As a last hail-Mary, the yellow bottle Trans-X can possibly help if you've got some varnish or goop clogging something up or making it drag when cold. Don't expect miracles, but like Nate said above, it made a difference on my car when it was "Shifted by Helen Keller".

[moon161]

a 617 not getting up to temperature is likely a failed thermostat. The bolts on the flange of the thermostat housing, particularly the lower one, tend to be corroded in place and easy to break. It's a good idea to have a spare housing and/or tools and a plan to replace a broken bolt before you attempt to replace the thermostat. Searching the forum will give many examples.

[Diesel911]

When I had that cold temp slip in first gear (it can get into the high 40 degree F at night and in the early mornings here in CA) changing the Filter and Fluid appeared to have fixed that. However, just about 1 year later my B2 Piston broke.

I don't know if the slip was a precursor to the B2 Piston breaking.

Does it also slip in reverse?

[Diesel911]

Again, is it slipping in reverse?

[pawoSD]

Are you running normal dinosaur based dexron trans fluid? Or synthetic trans fluid? When I switched all of mine to Dexron VI synthetic it made a HUGE difference in off the line cold performance of the trans, shifting was much better!

[Elyaouti800]

Originally Posted by vwnate1

When the tranny in my '82 240D was going, a member here suggested "Trans-X", I schlepped down to my FLAPS and they had multiple choices of this product, I tried the yellow bottle and added some, Lo ! . the tranny began to shift properly again and the ATF leak subsided too .

I was able to nurse another few years and 40,000 miles out of it before having the tranny rebuilt .

I did have to add more of this product occasionally .

Hopefully you drained the torque converter when you did the fluid and filter ? .

i put some of that trans x only it wasa a blue bottle and not a yellow bottle. Are there a diffrence between the two?


I then removed a quarter of transmission fluid from the pan then I put quarter of the transx in the transmission and put the 1qt of transmission fluid back in. The car shifts alot better than it did before it will slip occasionally but only if. I dont let it warm up

To answer your second question. I never did drain torq converter.

[Elyaouti800]

Originally Posted by Diesel911

When I had that cold temp slip in first gear (it can get into the high 40 degree F at night and in the early mornings here in CA) changing the Filter and Fluid appeared to have fixed that. However, just about 1 year later my B2 Piston broke.

I don't know if the slip was a precursor to the B2 Piston breaking.

Does it also slip in reverse?

car does not slip in reverse. When I am shifting through P,R,D,N. Its so smooth you dont even feel it. I will check the fluid level tommorow.


Btw whats the diffrence between the trans yellow bottle and blue bottle?

[Elyaouti800]

Originally Posted by pawoSD

Are you running normal dinosaur based dexron trans fluid? Or synthetic trans fluid? When I switched all of mine to Dexron VI synthetic it made a HUGE difference in off the line cold performance of the trans, shifting was much better!

i am using this
https://images-na.ssl-images-amazon.com/images/I/61KI4DD4MBL._AC_SL1500_.jpg

[Stretch]

You should be running Dexron II - if you can't find Dexron (which apparently is a common problem in the US) you'll have to ask others what works

A common mistake is that people think any old fluid will do

[Diseasel300]

Originally Posted by Stretch

A common mistake is that people think any old fluid will do

It's also a common misconception that only Dexron II will do.


I personally use the same red-bottle trans fluid as the OP and so do many other people on this forum and elsewhere. The shift quality is extremely good with that fluid, I have nearly 15K on my fluid change now with zero issues.


If the transmission is healthy mechanically, everything is adjusted right, and the fluid is at the right level, you should be feeling a firm engagement in gear when you shift from P or N. It shouldn't be rough, but you should certainly notice that it shifted into gear.

[pawoSD]

Originally Posted by Elyaouti800

i am using this
https://images-na.ssl-images-amazon.com/images/I/61KI4DD4MBL._AC_SL1500_.jpg

That should work fine, I ran that for 28k+ in my 190D Franken car and it never had any shifting issues or leaks in that entire time period (5+ years)