1984 300SD TRANSMISSION WOES???? UGH HELP! - PeachParts Mercedes-Benz Forum

DJNEWK2 · #1 02-19-2011, 04:58 PM

This is working my nerves as I've now got a total of 4 trannies.FOUR that I suspect are just fine and something else is the culprit. I picked up another 300sd a month or so ago and was going to put the motor into my other 300sd with a bad motor but decided to just wait on another motor and just drive em both eventually but about 3 weeks ago the "new" 300 seemed to slip just a bit as I was backing out of a parking spot as the back felt a little shaky until it caught and went into reverse. It would also rev a bit high before it shifted from 1 to 2 but the shaking in reverse issue was one time then like 3 days later after a long drive it wouldnt drive forward or reverse (Luckily it was AFTER I parked it at home)

My big mistake was assuming the tranny was bad and I bought another one and actually had all the seals replaced with new ones (which I still have but havent installed YET). While the tranny with the new seals was gonna take a few days to be done, I decided to take the tranny out of my other 300 with the bad motor because I'll probably scrap it (if anyone needs parts the body is in great shape). I KNOW that tranny is fine,shifts smoothly and I had a new filter,etc in it and its only been sitting in the driveway a few months. I had a "mechanic" and myself pull both trannies and put the other one into the "new" 300... While it was on the jack stands, shifted fine, reverse, drive,etc... He lets the car down kinda hard. Not slamming it but I'd do it softer lol. I'm able to back the car up out of the driveway to clean up and after that the car didn't move again under its own power so we've pushed it back into the garage and on stands.

I'm able to put it in gear and the flexdisc,etc is correct the drive moves the wheels very slowly and I can stop it with my hand from spinning... it stops if its in park but only moves forward slowly when in drive and reverse but again its almost as if its only moving from vibration or something. Anyone know if it could be something else? OH THIS IS THE KICKER: We were ready to scrap the old tranny but we pulled the pan and NO shavings,leaks and fluid looks fine with no burning smells so it looks like the "bad" tranny is still good! I was thinking about the piston or something but I had to remember that THIS tranny just came from my former daily driver with NO SLIPPING,ETC... I do remember when I'd drive it seemed to have a strange whistle sound when I get up to 35-40 as though someone was in my right ear behind me in the back seat. Could it be a rear end issue?

I'm sorry this is so long but this thing has been going on for weeks now and I'm sick of this nice looking car not being able to enjoy this nice driving weekend here in Georgia! If anyone has any expertise on this pleeeeease chime in and thanks for the help I've always gotten on this goldmine of a forum...cheers and wish me luck

barry123400 · #2 02-19-2011, 05:57 PM

Differential bad or one drive axle separated in a cv joint? Put the emergency brake on and try to turn the driveshaft with a pipe wrench with a cloth under it to minumise drive shaft scars. Not in park of course.

Use the same torque converter in the swapped transmission? Crank shaft could be broken close to the end but I doubt it.

engatwork · #3 02-19-2011, 06:10 PM

Is the transmission fluid level up to where it is supposed to be? The transmission has to be hot to get an accurate reading.

carat 3.6 amg · #4 02-19-2011, 06:42 PM

Have you changed the tourqe converter or is it the original? If it is original, undo the drain bung and see what comes out. My 560sel had a similar problem that I only cured by replacing the tourqe converter. Hope this helps

DJNEWK2 · #5 02-19-2011, 06:59 PM

Used the same torque converter that I took out with the other trans that was running-- fluid is fine (actually I kept adding fluid gradually until it was overfilled at one time and let it run the excess out then checked again...still won't budge... there is some black fluid drops at the rear end's passenger side wheel boot connecting to the differential though... is this a possible culprit?

DJNEWK2 · #6 02-21-2011, 11:50 AM

Anyone? Anyone? Anyone? Farris Beuller teacher voice

tbomachines · #7 02-21-2011, 12:56 PM

At least the very first transmission you described sounded much like a fluid level issue.

carat 3.6 amg · #8 02-21-2011, 03:56 PM

A shot in the dark here, but dose your car have a gearbox oil cooler? Could the lines or the cooler itself be blocked, starving the return side of oil? Highly unlikely I know, but the fact the car reversed out of the workshop and then would'nt move again, makes me think something is being starved of oil.

DJNEWK2 · #9 02-21-2011, 06:20 PM

Dunno about the gearbox oil cooler cause I dunno where that is... I'm wondering what it could be as well but so far everything looks to be fine as far as fluid level. I read about vac importance with these and wondering also if something was jolted loose when it was lowered down kinda hard (just a shot in the dark as well)...does anyone know if this sounds about right as far as vac pressure to get the trans to function or should I just snatch out my rear end out of the other 300 and swap since I do see a little fluid from the boot of the rear passenger wheel shaft to the rear diff on the floor? This seems like its gonna be something so simple but has been anything but. ugh

barry123400 · #10 02-22-2011, 01:29 AM

Well until you see if it is possible to turn the driveshft with the emergency brake on and the transmission out of park you will not know if the drive portion of the rear end is intact. Pretty simple test.

Or put the nosse of the car against something solid. Run the engine in drive and have a look if the driveshaft is spinning. Simple test as well. Just use common sense when doing it.

DJNEWK2 · #11 02-22-2011, 11:02 AM

I've had her rear wheels up in the air and putting it in drive,reverse and the drive barely spun (and I'm able to stop it from spinning with my hand)-- but I have just started it,put it in drive (also did it in N) with the E-brake on and was only able to move the shaft back and forth and inch or two before it stops. Same when I got up and moved the rear wheel (only moved and inch or two then hear the clunk as it stopped)... should that be normal?

DJNEWK2 · #12 02-22-2011, 11:03 AM

AN inch or two not AND lol...

carat 3.6 amg · #13 02-22-2011, 03:37 PM

Quote:

Originally Posted by DJNEWK2

Dunno about the gearbox oil cooler cause I dunno where that is... I'm wondering what it could be as well but so far everything looks to be fine as far as fluid level. I read about vac importance with these and wondering also if something was jolted loose when it was lowered down kinda hard (just a shot in the dark as well)...does anyone know if this sounds about right as far as vac pressure to get the trans to function or should I just snatch out my rear end out of the other 300 and swap since I do see a little fluid from the boot of the rear passenger wheel shaft to the rear diff on the floor? This seems like its gonna be something so simple but has been anything but. ugh

Jack up the front of the car and look at the bottom of the radiator, you should have two small pipes going in to the bottom of it. Put a drain bucket under the radiator and carefuly undo the pipe unions (they will be rusty), this should drain the radiator of transmission fluid. Position both pipes so any fluid will spray into the bucket. Now for the messy bit! Get a freind to run the engine for a few seconds while you check to see which pipe the fluid comes out of, re-connect this pipe to radiator and run the engine again. If the oil cooler is blocked then no fluid will come out of the radiator, if it sprays fluid then its not blocked.

DJNEWK2 · #14 02-22-2011, 06:44 PM

Oh yeah I meant to share that info as well... I didn't get your cooler comment at first because you said "gear" which threw me off a bit but yeah I did check the cooler lines (and have a new pair of lines that were gonna be for the other 300 but will def go on this one IF I CAN GET IT TO FRIGGING MOVE UGH)... Mine weren't rusty shockingly either but thanks for that suggestion. Do you know if me being able to move my driveshaft AT ALL while out of park with the E-brake on would constitute an issue with the rear end because I KNOW I don't have 4 bad transmissions and torque converters

carat 3.6 amg · #15 02-22-2011, 07:30 PM

Quote:

Originally Posted by DJNEWK2

Oh yeah I meant to share that info as well... I didn't get your cooler comment at first because you said "gear" which threw me off a bit but yeah I did check the cooler lines (and have a new pair of lines that were gonna be for the other 300 but will def go on this one IF I CAN GET IT TO FRIGGING MOVE UGH)... Mine weren't rusty shockingly either but thanks for that suggestion. Do you know if me being able to move my driveshaft AT ALL while out of park with the E-brake on would constitute an issue with the rear end because I KNOW I don't have 4 bad transmissions and torque converters

It sounds like you've got a bit of wear in the differential but I dont think thats your problem. In my w124 I can apply the e-brake and still be able to turn the gearbox flange an 8th of a turn both way's, thats normal. If you had a rear end problem, you wouldnt have been able to reverse the car out of the garage to clean up.