Transmission reluctant to shift into 3rd on first run of the day - PeachParts Mercedes-Benz Forum

jbach36 · #1 09-22-2007, 04:58 PM

Just a few weeks ago, my transmission was reluctant to shift into 3rd as it normally does, around 40 mph or so. I find myself doing 40+ in 2nd gear and the rpms's are above 2000. I'll slow down to about 20, then go back up toward 40, and the same thing, won't shift. I'll try a 3rd time, then it will reluctantly shift into 3rd, then I'm doing 40 mph at around 1700 rpm which is normal. It runs the rest of the day fine. It did this for a few days, then shifted normally, then started doing it again.

I checked the transmission fluid level. It was slightly low (less than 1/4" on the dipstick). I thought the small leak in the garage was power steering fluid, but turns out now might be the transmission leaking a bit, very small amount. I filled the fluid back up. The new fluid that went in of course was nice and pink on the paper towel I used to check the fluid. The used fluid in the transmission, though not brown or burned (burned is very brown and smells like burnt toast), wasn't pink anymore, more a light tan. I last had the transmission fluid changed around 90k, it now has 111k on it. I did a visual inspection of the vac hoses, they all seem to be hooked up fine, and I replaced the little filter in the passenger wheel-well area of the engine, the one that goes to the vac pump.

The transmission worked normally again for a few weeks, now back to the same thing. It's possible temperature change is causing this, but it didn't do this last year at all.

Any suggestions?

Thanks,

Jeff 1991 300d, 111k

Ken300D · #2 09-22-2007, 08:43 PM

I strongly recommend Mobil 1 Synthetic ATF, and recommend you change your fluid and filter and go with this product.

The synthetic ATF has better cold weather viscosity, and provides a much greater cleaning capability. Sometimes the valve body bores and pistons get gummed up with varnish and don't move smoothly - the Mobil 1 ATF will clean all that varnish out. While it is certainly not the only thing that can cause your problem, it frequently is the fault of the valve body components involved in poor or late shifts, especially when cold - and then shifts find when warmed up.

Ken300D

jbach36 · #3 09-23-2007, 04:05 PM

Quote:

Originally Posted by Ken300D

I strongly recommend Mobil 1 Synthetic ATF, and recommend you change your fluid and filter and go with this product.

The synthetic ATF has better cold weather viscosity, and provides a much greater cleaning capability. Sometimes the valve body bores and pistons get gummed up with varnish and don't move smoothly - the Mobil 1 ATF will clean all that varnish out. While it is certainly not the only thing that can cause your problem, it frequently is the fault of the valve body components involved in poor or late shifts, especially when cold - and then shifts find when warmed up.

Ken300D

Yeah, but if we're talking about "when cold", I'm in Atlanta, and we've gone from 103 degree temp in the shade to 92 in the shade and it started doing it. We're not talking 10 degrees in the winter time, that's what scares me. Now we're at maybe 75 when I first drive it for the day.

jeff

junqueyardjim · #4 09-23-2007, 05:15 PM

Then your transmission was not only low, but your fluid being brownish or tan and having the smell of burnt toast is eating your transmission alive. Get rid of all that old fluid now, in both the transmission and the converter. Tomorrow may be too late. If it really is that bad, I would do a filter and fluid change and at this time refill with Dextron 2 or 3. It is much lower in cost, and if it seems the transmission will continue performing well, then a second change to synthetic fluid would be a good idea.