Bad leak 85 300 SD transmission pan - PeachParts Mercedes-Benz Forum

yuke · #1 10-01-2014, 02:54 PM

I have noticed a bad leak from my pan since the car has been up on blocks waiting for driveline parts. At first I could not believe the puddle was trans oil as it looks more like motor oil not red in color. I am going to drop the pan and try to reseal with either a new gasket or some type of sealant on top of gasket that is there. The reason I might just go with a sealant is the fluid and pan gasket were changed about 2 yrs. Ago and I remembered it leaked right from the get go left mechanic know about leak but notning was ever done about it. So now I will try to resolve issue. What type of trans oil is recommended and would sealant be a good idea. Trying to get rid of oil leaks on this car as it has many.Strange when I drained fluid at drain on pan I only got 2 qts. out when book says it holds over 7 qts. and when I check on dipstick it still reads about 7/8" below low mark. Is that all you are gonna get out of the pan? Would you have to drain it 3 or 4 times to get a total fluid change?

JamesDean · #2 10-01-2014, 02:59 PM

I would buy a new gasket, I would not rely on any sealants. Make sure that lip the gasket goes on it not warped or anything and do not over torque the pan bolts.

As far as ATF: Dex III.

I've been using Valvoline's Dex/Merc MaxLife in all of my transmissions: Valvoline.com > Products > MaxLife > Automatic Transmission Fluid MaxLife > MaxLife® DEX/MERC ATF

Did you end up finding the cause of your vibration?

yuke · #3 10-01-2014, 03:18 PM

Quote:

Originally Posted by JamesDean

I would buy a new gasket, I would not rely on any sealants. Make sure that lip the gasket goes on it not warped or anything and do not over torque the pan bolts.

As far as ATF: Dex III.

I've been using Valvoline's Dex/Merc MaxLife in all of my transmissions: Valvoline.com > Products > MaxLife > Automatic Transmission Fluid MaxLife > MaxLife® DEX/MERC ATF

Did you end up finding the cause of your vibration?

Thanks Kris I think I remeber the pm did tell he thinks the pan is bent tried to straighten it but it did still leak I would think that when you tighten up on bolts it should take care of any warpage. I tried to tighten some more bolts are very tight and still leaked just sitting there up on blocks sure hope I do not need another pan. Will inspect more closely when I pull it off. I am still waiting for driveline parts will post results when installed hopefully by weekend.

JamesDean · #4 10-01-2014, 03:26 PM

I've been down that road with both of my SD's. I put the bolts on and then found that it leaked so i tightened them up. This ended up warping the pan at that flange and then damaging the gasket itself.

I decided to play it safe and bought a new pan. They are $60-80 depending on where you buy it from.

Are you planning on changing the filter as well?

cho · #5 10-02-2014, 09:00 AM

Quote:

Originally Posted by yuke

Strange when I drained fluid at drain on pan I only got 2 qts. out when book says it holds over 7 qts. and when I check on dipstick it still reads about 7/8" below low mark.

strange indeed last time I drained mine it was approx 5+1 in converter
maybe your filter or somethin' is plugged?

.

bolzano · #6 10-03-2014, 12:46 AM

Quote:

Originally Posted by JamesDean

I've been down that road with both of my SD's. I put the bolts on and then found that it leaked so i tightened them up. This ended up warping the pan at that flange and then damaging the gasket itself.

I decided to play it safe and bought a new pan. They are $60-80 depending on where you buy it from.

Are you planning on changing the filter as well?

Found tightening trans pan bolts tighter than spec only cuts through the pan gasket. On U.S.A. style trans pans, the edge where the bolts go is flat. Is rounded on MB so tighter bolts tends to get the pan to cut through the gasket.
So, try to straighten the pan if needed, use a new gasket and tighten only to 7 or 8 Nm.

Mercedes 300d http://ts1.mm.bing.net/th?&id=HN.608012724829095066&w=300&h=300&c=0&pid=1.9&rs=0&p=0

Chrysler 31th http://ts1.mm.bing.net/th?&id=HN.608019008363169406&w=300&h=300&c=0&pid=1.9&rs=0&p=0

What ATF? Regular Dexron III.

SD Blue · #7 10-03-2014, 01:42 PM

Doesn't the 85 have the torque converter drain plug? I have never gotten much more than ~2 qts from the pan only.

The transmission pan is similar to the valve cover gasket. (It must be a particular with rubber gaskets.) I had good results with an initial tightening and then another tightening after the transmission was warmed up. Unless you are really good, I found a torque wrench was pretty much mandantory to get everything evenly tightened. Overtightening seems to warp the pan and anything you do seems to make it worse. My pan was warped from the start and I ended with replacing it rather than deal with the frustration of constant leaks.

bolzano · #8 10-04-2014, 12:00 AM

Quote:

Originally Posted by SD Blue

Doesn't the 85 have the torque converter drain plug? I have never gotten much more than ~2 qts from the pan only.

Yes. There is a torque converter drain plug. See page 2 of file 2702 from the service manual. See attachment. Turn the engine with a large socket and breaker bar or ratchet handle in one hand. Feel for the TC drain bolt with the other as the engine turns. I think it was an allen head drain bolt. Now that you will be able to drain several quarts, only fill with 4 quarts before starting the engine and adding the rest or the transmission will overflow.

yuke · #9 10-07-2014, 04:50 PM

As far as for the leak on the pan I got about 2 qts. out of the pan and about 2 out of the converterter and keep plenty of newspaper underneath as it will drip for days yet with no pan on. On install with new gasket and proper torqueing 6' lbs. on refill and startup it dripped immediately. Took pan back off put a straight edge on it and it looked to be warped so I procedded to try to straighten on reinstall I put some sealant on area where it was leaking which was where rubber gasket meets pan did not leak at all on top side where gasket meets trans. Put a little over 6 qts. Back in and does not seem to be leaking any more will continue to monitor it hoping problem is solved.

vtmbz · #10 10-07-2014, 08:17 PM

Clean fluid is essential for proper operation. I would be concerned that sealant might float free into the transmission. If at all possible, replace the pan with another from the JY that is not warped, clean it carefully, remove all the sealant from the trans body and replace the gasket. You now know how to do it correctly, so heres your chance!

Transmissions are very expensive and very cranky. If you only got 4qts out, then you were running quite low, and the fact that it hadn't started slipping is lucky indeed.

yuke · #11 10-08-2014, 09:54 AM

Wow I just cant win with this trans leak. After having the pan off twice I put 4 qrts. In started it worked oil into convertor put about 2 more qts. in for a total of a little more then 6qts. Ran car checked underneath no leaks. Drove car 150 miles shifted okay no leaks checked oil and it read a little low on dipstick so with engine at temp. I filled oil to get it between 2 marks on dipstick it might of took at most 3/4 of a qt. Looked underneath and it seemed was leaking out as fast as I put it in same spot where it leaked before middle of pan on passenger side where there is a bolt and ear . Maybe I should have left it a little low instead now I have to drop pan again and try to figure this thing out. Never had problems with other pans on other vehicles do not know what it is with the design of this one on M.B.s

JamesDean · #12 10-08-2014, 10:01 AM

I think once the pan is warped the best and least painful solution is to just buy a new pan. They can be had for $60-70 toss in a filter and gasket kit and you should be under $100 surely cheaper than to keep feeding it ATF and having to deal with it repeatedly.

Been there and done that on two 300SD's. I hate pan gaskets.

Zulfiqar · #13 10-08-2014, 10:42 AM

MB transmission pans require a very gentle torque - something like 60 in/lb - loose leaks - and tight also leaks. Lay the pan upside on a granite counter top and see if it sits square, if you see it crooked - try to bend it back to shape - if you cannot get it back to completely square state then get a new pan.

if you dont have a torque wrench with that low of reading then use a nut driver and get them very gently snug - or use a 1/4 inch ratchet pulling with your pinky finger (assuming you are not an ogre like me). My W124 pan gasket was leaking because of improper tightening and used to leak out about a quart every 6000 miles, new gasket + filter + ATF + correct procedure and its dry as bone ever since.

yuke · #14 10-13-2014, 01:22 AM

Finally after having this pan off 3 times I think leak is resolved. What happened was after putting pan on a second time with new gasket with sealant at spot it leaked at+ filter torqued everthing to spec 6' lbs. everthing seemed fine after driving it a bit seemed to need a topping off to get at the proper spot on the dipstick. When I topped it off it leaked out as fast as I put it in making a big mess on the floor. Pulled pan back off and saw gasket was ripped. Reordered gasket and wrong one came in so in disgust of lost time decided one more time to really try to straighten pan and make sure all bolt holes line up correctly. I used old gasket that still looked good and put a film of heavy grease on both sides of gasket. I put all bolts on with a nut driver no torque wrench tightened equally and no more leak finally. I did notice when pan was off that when the fluid is up to upper level on dipstick you have a full pan of fluid so you do not want to go above the full mark. It seems hard to get a good reading when engine is idleing seems easier when engine is off and cool so according to owners manual I put the level about .2 below low mark on stick which means I put back in about 6.5 qts. which is where I wanna be. Wow I was almost ready to order a new pan what an ordeal.

JamesDean · #15 10-13-2014, 08:29 AM

I hate doing transmission pan work.

I too would be disgusted with having to take the pan off three times.

Do you reuse the ATF or put new in each time? New would be costly after 3x

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