Hi

Changed the ATF today. M103 engine and 4 speed gearbox (1990). Encountered a number of problems:

1) 5mm hex drain bolt would not undo. The hex stripped! Therfore had to drain fluid by taking pan off, not too much of a big deal since had to change filter anyway. Anyone have any tips on getting the drain pug out for next time?

2) Could not drain torque converter. After stripping the drain pug hex was not too keen to apply too much torque. How much fluid did I leave in the torque converter and will it make much of a difference?

3) Fluid level now a bit high. What effect will this have on gearbox? Should I remove some by sucking it from the dipstick?

Thanks in advance

Regards

I would definetly remove the extra fluid. Too much can cause damage. As for the stripped drain plug in the pan, I would first see if a new one is available. If there is, then I would use a drill bit that is smaller than the diameter of the drainplug and drill a hole through it. Use a tap and die set and unscrew the remains, then install the new one. Actually if you have a reversible drill, drill it that way. The force should free up the plug. Again, though I would first get a new plug.

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1999 MB SL500 (110,000 mi)
2004 Volvo V70 2.5T (220,000 mi)
2014 Tesla Model S 85 (136,000 mi)
MBCA member

I just did mine a month ago on a W201 engine. My manual stated that to drain the t-converter, you need to line up the drain screw with the small hole in the converter cover. This is possible with 2 guys and a car lift, but not if you are doing it with ramps or stands. I did not do it, and instead pulled off the pan and removed the filler/dipstick. After letting the car sit and drain, I noticed the fluid gurgle and a bit more came out. Maybe the converter released it? Anyway, I don't think you will ever get all of the fluid out without pressure. You will notice the book gives a flush fluid amount and a simple replacement amount. Flush gives a bigger replacement amount.

I would suggest not worrying about the converter and put new fluid and filter in. If you have a fluid extractor (Griot's Garage in the US has them online) you can easily pull out a few qts/ltrs from the filler later and add some fresh fluid. You may want to do this after a month or so of driving....give you the peace of mind that the tranny has very clean fluids.

As far as the drain bolt. You could either leave it in and start using a fluid extractor (thus never needing the pan bolt) or work on getting it out before you decide to put the pan back on. Maybe take the pan to a shop and have it tapped or drilled out?

Another thought would be to buy a new pan and bot....probably not too terrible a cost.

At least the pan can be taken off and dealt with on the bench or in a shop. I hate playing blacksmith when parts are still on the car!

For the torque converter try a different 5mm allen wrench. Yours may be worn with a rounded tip. Grind some of the tip down to get sharp corners. Clean the bolt hole of any crud that can prevent total engagement.

I believe the aluminum washer is the problem. It galls readily. I'll have to remember to replace it with copper next time.

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95 E320 Cabriolet, 159K

Try finding some valve lapping compound. It is a gritty paste that you put on your allen. It often will take up enough of the slop to allow you to get the bolt out.

If your allen is worn also try using a hex head of a similiar size, It has more surface area and grippers.

ALWAYS whack an allen an extra time to make sure it is fully seated. Always, double-whack an allen to make sure it is fully seated. Check the head also for dirt and debris. If in doubt: clean it out.

If your allens are worn, throw them away or grind down the ends so you get a clean perpendicular surface.

Haasman

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'03 E320 Wagon-Sold
'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
'91 300E-Went to Ex
'65 911 Coupe (#302580)

if you remove the spark plugs and that shroud around the the fan you can hand crank the engine pretty easily with a socket and wrench on the crank bolt to find where the drain plug is. my problem and i've heard its "normal" is a leaking pan.

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Ken
87 190E2.6

If I have a stuck one, first I tap on the head a little with a hammer (I usually do this with the pan still bolted to the transmission). Then I use a small or medium chisel and chisel at the edge so that the force is directed in a counter-clockwise direction. Works good, just be careful so the corner of the chisel doesn't damage the pan. This is quite common, especially if the transmission hasn't been serviced for a long time or if the plug was overtorqued.

You left LOTS of fluid in there, more than what's in the case!
Maybe you need either a better tool (as Haasman hinted at) or more guts, don't know which. You using name-brand tools, or just some no-name cheaper stuff? You can also use a punch and tap into the center of the hex-shape, this can help it loosen up easier with the tool.

YES you should correct the fluid level. Sucking out the tube is OK, I would recommend starting over and replacing the fluid again, and remove both plugs this time, probably just leave the filter alone if you just did that. You can buy new drain plugs for it.
Torque the oil pan bolts at 10nm, and both drain plugs at 14nm.
Use an aluminum seal ring on the torque converter, and a copper one on the pan.

I'd like to know what "book" gives a flushing amount for a Mercedes transmission, certainly not one published by Mercedes. Don't even go there!

Gilly

PS Make SURE you get the old seal removed from the torque converter. If you didn't have one to remove from the converter drain plug, it's probably mashed into the torque converter around the drain-hole. Remove it!

Thanks for the replies.

Will rectify the fluid level ASAP. and have a go at the torque converter.

Regards