Torque and crush rings

[JWHITE518]

Last fluid change I guess I didn't tighten down the transmission drain plug enough, and there was some seepage onto the exhaust system. Shtinky! I got out the wrench and cranked it down till it felt tight. No more leaky. The thing is, I had referred to the torque chart when doing the original oil change, but apparently that wasn't enough to crush the crush washer. What did I do wrong? What's the secret to avoiding leaks without overtightening?

 

[brianfisk]

my guess

my guess is that there was something (crap) between the crush washer and a sealing surface. It happens!

 

[BUBBAZANETTI]

is your torque wrench within spec?


i've stopped using torque wrenches with crush washers, they give a lot of "tell" before you start stripping threads.

 

[JimMoore]

The spec for the oil drain plug is 32 nm. The spec for some of the other plugs is only 23 nm. I've had the same problem you describe. I have always wondered if the 23 nm number had the numerals reversed in the original manual.

 

[hotspice]

I usually do crush washers in two stages. If the torque is 32nm I'll go through and tighten to say 22, then clean up some of my mess in the garage. Then I go back and do a final torque to 32nm.

I don't know if it makes a difference but I've never had any seepage, weepage, or leakage doing it this way.

 

[globalrider]

What's the secret to avoiding leaks without overtightening?

You shouldn't have to go beyond the recommended torque to seal any drain plug when using a NEW sealing ring each time.

Next time, check the sealing surface on the casing. If there is a problem, fix it. Don't over-torque the problem away.

For now, loosen the drain bolt a quarter turn and retorque. Wipe off any oil residue and check again a day later.