84 300SD-transmission problem help!
 

This car is new to me but apparently has never had transmission issues. It has been sitting for at least 8 months. I have driven around town for 3 days without a problem and began a longer road trip today of about 45 miles. At mile 40 it started to down shifted from top gear into 3rd and I took an exit and let it sit for a little while and checked the fluid. The fluid was a little high but only by 4-8 ounces. It was shifting hard when I took it back on the road and when I went back to the interstate it began to slip. And began to slip to the point to where I could not go forward anymore. I felt the transmission fluid radiator which was very very hot. When it cooled down I was able to drive again for a few miles until it heated up again.

I checked the transmission drain bolt and was going to drain the fluid. I realized it was stripped and understood by that the transmission fluid probably has not been changed for awhile.

Question-do you think the transmission is failing because of a clogged filter or bad oil? My first step is to drop the transmission pan and change the filter and the oil.

Any advice would be welcome. What is the size of allen bolt that holds the pan?

Thanks

Will

Countless transmission problems have been solved by doing just that.


Are you sure you weren't feeling the oil cooler?


Are you sure you are looking at the transmission oil pan?

I was having symptoms of a B2 Piston problem of not shifting into first Gear. Changing the Filter seems to have resolved that.
Unless you have some way of rethreading the Transmission Pan I would get another one.
Maybe a member has a used one.

Just firing up and driving a car that sat 8 months is an unwise course of action. Why did you not change the fluids and filter first??

Most likely, "stripped" refers to the hex recess in the drain plug. Removing the drain plug is not necessary; plenty of transmission pans don't have a drain plug. Just remove the pan, which is a necessary step for replacing the filter, anyway.

so... on the side of the road, you not only removed some fluid, but you know exactly how much you removed to get the level correct?

and what transmission fluid radiator did you feel? unless you have an aftermarket cooler installed, the trans cooler is inside the bottom reservoir of the radiator... you might be feeling the engine oil cooler that's on the driver's side of the radiator...

I did not think about the hex being stripped.

And, I have owned 2 Cars with no drains on the Pan.
On both I made my own drains.
I found that without a drain I just make a bigger mess of things and I put off changing the Fluid and Filters longer than I would if I had an easy way to drain them.

It could be he thought the Engine Oil Cooler was the Transmission Cooler.

Change fluid including the torq converter; change filter, fix drain plug, refill & go from there.

The simple things do more for these cars than any others I've driven. Wonderful pieces of equipment.