seankrider

So in the course of replacing my oil this weekend, I managed to finally strip the Torx (or Hex?) threads from one of the aluminum oil drain plugs such that he bit would turn round and round.

Luckily, knowing that it would happen eventually I had the foresight to order the steel magnetic replacements ahead of time. I'm sure I over-torqued them or this wouldn't have happened in the first place, and yes I know the originals could last a lifetime, blah-blah-blah. None of which helps when it happens. All I knew at that point was the aluminum is soft, which makes it a challenge to get out once stripped.

Some of the other forums (i.e., 944) had similar war stories, so I'll cut to the chase and tell you that (a) an easy out/left-hand bolt remover did not work; (b) the little Dremel-notch/flat-head trick did not work; and (c) moving up to one size larger bit trick did not work.

But after 20 mins of Googling on my iPhone under the car, this trick finally worked: hammering a (sharp) triple-square into the rounded-out hole and wrenching it out:



Hard to see entirely, but this was what I pulled out:



So I've got a triple-square-threaded aluminum drain plug, if anyone needs one...

kosmo

Hows the pan itself?

seankrider

Pan's fine, as far as I can tell. Threads are still good, and the new steel drain plug is in finger tight + about 1/8th turn.

Lightningmcnulty

What is the tightening torque required on the drain plug?

I have seen the result of under torqued drain plugs and i'd much rather replace the plug that the engine!

Chris51080

Over on renntech, the DIY calls for 50Nm, or about 37 ft/lbs.

http://www.renntech.org/forums/tutor...ia-oil-change/

DWPC

How hard was it to break loose the plug? Had it siezed? I'm suspect of threads in aluminum and always use anti-sieze compound on them.

dryadsdad

Darned easy too to strip the threads on the pan now that you have a steel plug. I've done it more than once but not on a pan. Steel screws in aluminum parts are very common on bikes which is where I generally wrench (poorly).

fast_freddy

Steel plug in an aluminum case? Hello galvanic corrosion! I'd do one of two things, anti seize the ever living crap out of the plug and change the oil often and relube the plug every time and be oh so careful not to cross thread. Alternatively, just get another aluminum plug and call it a day. I'd go with the latter.

stronbl

37 ft-lbs for v6 and v8, but 22 ft-lbs for diesel and hybrid.

spooltime

Just did an oil and filter change yesterday on my CTTS and looked up the torque values for the oil drain plugs and oil filter housing in the factory service manual before starting since I couldn't remember them from the last time I changed the oil.

I'll confirm the 50 Nm for the drain plugs and note that the oil filter housing torque value is 25 Nm. See the attached extracted page from the shop manual.

dryadsdad

Doesn't seem to be much of a problem, for some reason. Very common, actually.

grohgreg

I'm going to speculate that the presence of corrosion preventatives in the engine oil minimizes the electrolyte level necessary to actually catalyze galvanic corrosion.

//greg//

dryadsdad

Makes sense. Then again the alloys may be such that there isn't that much potential there.

Years ago, I attached some winches to an aluminum mast using stainless fasteners. Even in a salt environment, I didn't see much corrosion.

fast_freddy

Don't hold your breath on that one. You're assuming that the oil gets "replenished" on the threads, it doesn't as its "sealed".

I've witnessed many aluminum alloy seat-posts and stems on bicycles completely seized in steel frames even when adequately greased and/or anti seized. With the threads on these things I imagine they're fairly precise/tight and doesn't give much room for grease/anti-seize. It simply isn't worth the risk. Additionally, if some dip**** changing the oil cross threads (assuming someone other than yourself changes the oil), You.Are.Fooked.

seankrider

Good insights, all around. I actually love that there is never a 100% consensus on anything in this forum (except our intense love/hate with these biotches). Great dialogue all around... though I'm surprised there was not more sarcasm or dry humor.

Truth be told, I went steel for the magnetic properties like in the transmission pan. And I'd heard that similar upgrades been used very successfully in other applications (i.e., aircraft).

Now in another 50K miles when I start a post on replacing a cross-threaded oil pan or seized bolt or galvano-corroded whatever, then loose the pundit hounds!