Re-torquing pan and cover bolts.

[Loobed]

Is it a good idea to re-torque automatic transmission pan bolts, and differential cover bolts? I tightened mine to specification with a torque wrench when I serviced them. I recently checked the transmission pan and the bolts were loose. I can't remember if I used gasket sealer on the pan, but I don't think I did: At least not on the, milled flat, housing side. I also used an aftermarket gasket, not the factory one. I was told that it is normal for the bolts to loosen because the gasket flexes or shrinks. The factory bolts didn't come loose.

 

[Doog]

Don't wake a sleeping baby.....don't re-tighten things that are not leaking....or fix it til it's broke.

 

[Loobed]

Actually the pan was leaking which is why I checked the bolts. My rear cover also has some seepage, but I have not re-tightened those bolts yet.

 

[JOD]

If it's leaking or seeping, the joint has obviously failed--so re-torque the bolts for sure. Bolt relaxation and gasket creep are going to effectively loosen the joint, no matter what you do. OEM's are able to minimize this by tightening the bolts to a higher tolerance (reduces bolt relaxation) and by tightening all of the pan bolts at the same time (greatly reduces gasket creep). It's impossible to duplicate this yourself!

On transmission pans in particular I think it's always a good idea to re-tighten the bolts after a few days.

 

[rationull]

Originally Posted By: JOD
... and by tightening all of the pan bolts at the same time (greatly reduces gasket creep). It's impossible to duplicate this yourself!


Maybe not, you just need about 20 friends and an equal number of ratchets with long flexible extensions!

 

[JOD]

Originally Posted By: rationull
Originally Posted By: JOD
... and by tightening all of the pan bolts at the same time (greatly reduces gasket creep). It's impossible to duplicate this yourself!


Maybe not, you just need about 20 friends and an equal number of ratchets with long flexible extensions!


I can see the Evite now: "Oil Pan Tightening Party at JOD's House. BYOW!" It'll get a little crowded under that car, though...

 

[doitmyself]

I did my tranny pan very OCD, following the tightening pattern in my FSM. I must have went around it 5 times (fourteen bolts?) gradually torqueing it to 10 ft. lbs. in steps.

A month later it was seeping (just wet) in one corner, so I tightened each bolt 1/8 turn, then did this again a month later.

I used a very stout Felpro gasket.

IMO, torque wrenches on "soft" gaskets are tricky. The material compresses, relaxes, and then is under tightened. One time I actually kept re torqueing a gasket to 10 lbs. and ruin it by squeezing it out.

I imagine pros do this by feel and tighten a bit more than needed to not get call backs.

My technique now is to get them up even by torque wrench just one time to the recommended torque (still in cross pattern multi steps). Then if leakage occurs, I tighten each bolt 1/8 to 1/4 turn until seepage stops.

Or.....I just do them by feel from the get go...depends how much I want to "play". Yes, retightening is sometimes needed.

 

[JOD]

Originally Posted By: doitmyself


A month later it was seeping (just wet) in one corner, so I tightened each bolt 1/8 turn, then did this again a month later.



I think that's a good strategy, and pretty close to what I do; add 1/8th of a turn after 24 hours, an 1/8th of a turn after a month, and them I'm done.

I do think it's pretty important to follow the tightening sequence and method (generally make 4 passes in ~25% increments) so that you press the gasket as evenly as possible. Dual-compound gaskets also help (say a rubber gasket with RTV or a commercially-available dual-compound gasket), but that's not always an option.

 

[MetalSlug]

I alway retight tight up the bolt after day or 2, when im doing rear diff or tranmission pant bolt.

 

[mechtech2]

If they are leaking, you could try a gentle retighetning.

I often use sealant where it is not required because I don't want comebacks or leaks.