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Correctly Torquing Rubber Gaskets

So anyway, I've decided to change the ATF and filter on my Mercedes E270 CDI which I keep as a spare cheap runabout. Only paid the equivalent of 2 grand for it. It's showing 135k miles but has been well looked after by previous owners. I know these auto boxes are supposed to be sealed for life and maintenance-free but that's a load of old cobblers as I think we all know by now. Anyway, the oll pan on these 'boxes uses a 'U' section rubber gasket; the lip around the edge of the pan fits inside this U. So I've done up the bolts and filled it back up with ATF. They say you should warm up the engine and check the level with it running in park after cycling through N,P,D and R a few times. Anyway, to cut a long story short, ATF was pissing out everywhere. I admit I got lazy and didn't use a torque wrench to do up the bolts, but I did check to ensure the gasket was still correctly seated over the pan's lip after doing the bolts up. I can only think the problem came from not using a TW, but could that really cause it? How fussy are these rubber gaskets WRT torque settings?

Reply to
Cursitor Doom
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My bet would be that you have got a mechanical problem somewhere, perhaps a cut gasket or a significant lump of trapped debris.

Garages use pumps to suck out oil out from sump and gearbox fillers for a reason.

Reply to
newshound

Yes, that and/or the securing bolts weren't torqued up to the same level, causing the cover to warp slightly - easily done if access difficult. Learnt this the hard way with a water pump cover.

Consistent torquing is at least as important as level.

Reply to
RJH

Agree 100%. I don't know the geometry of that sump, but traditional pressed steel engine sumps with thick cork gaskets usually had lots of bolts, making them slightly less sensitive. Water pumps were always prone to that.

Reply to
newshound

Dunno why I didn't think of just posting a link to the damn thing!

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This is the top view they're showing, so the hollow of the 'U' section that the lip of the pan fits into is not visible from this angle.

Reply to
Cursitor Doom

I'm guessing it does not have that many bolts then. That said, I'd expect a Merc sump cover to be pretty well designed against deformation either from variable torque or temperature effects. IME relatively thick rubber gaskets and washers, provided they are adequately constrained, are normally *very* reliable. As I said, I'd expect the cause to be large debris or damage to one of the three parts, all of which should be revealed on dismantling.

Reply to
newshound

Many autos require a filter change at the same time as the very infrequent fluid changes.

Reply to
Dave Plowman (News

These aren't the monolithic type built in to the pan like some are. But they're just push-in; couldn't be simpler so yes, I'll be changing that at the same time.

Reply to
Cursitor Doom

Duly noted, Newsy. I only suspected it was deformation because I'd reached the point where the bolts wouldn't turn any more - which didn't seem right and no, they were not x-threaded or anything. And this was at no great torque, too. I do have a TW ideal for this purpose but couldn't grab it without getting out from under the car and walking 20' and back. An unforgivable bit of laziness on my part I admit. :(

Reply to
Cursitor Doom

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