What would you do please?

[belfry]

I was helping my friend to change the transmission fluid and filter yesterday. When my friend was reinstalling the 14 pan bolts he snapped the final one. We noticed that the torque wrench was set incorrectly. We will remove the broken stud with a reverse drill bit and replace with a new bolt.

My my question is, do we need to “un-tighten” the remaining 13 bolts? The gasket is a squishy rubber part about 10mm deep. Each of the 14 bolt holes have a 5mm anticrush washer (I guess to stop people like us over tightening the bolts and distorting the gasket.

The pan pan is not leaking so would you bother to loosen the other 13 bolts or leave them be?

many thanks

[Paul_M3]

What was the torque wrench supposed to be set to, and what was it actually set to?

[paintman]

If it really bothers you drop the sump & refit with a new gasket with all properly torqued.

If it doesn't just replace the broken one at the proper torque & leave the rest alone.

I'm assuming it's the type with a metal tubes at the bolt holes so Guy the Gorilla can't overtighten them by swinging on the wrench

Edited by paintman on Thursday 18th March 18:29

[E-bmw]

If it is up to 25% out, I would just undo/redo them correctly, and hope that it was probably a weakened bolt.

Any more than that & I would be expecting to replace them assuming that the over-torque was to blame.

[belfry]

Paul_M3 said:

What was the torque wrench supposed to be set to, and what was it actually set to?

They are supposed to be torqued to 4.5 ft/lbs. The torque wrench never clicked but the bolts seemed to be quite tight (and the last one snapped).

I don't want to have to go through the whole drain/refill/buy new gasket if I can help it. I will replace the broken one, but will the other bolts being over-tightened cause damage down the line?

[DVandrews]

If they haven't yielded, then leave them till the next time you remove the pan, then examine them and if they are not stretched in the thread, the chances are they will be fine, if you are bothered replace them all at that time.

Dave

[E-bmw]

belfry said:

Paul_M3 said:

What was the torque wrench supposed to be set to, and what was it actually set to?

They are supposed to be torqued to 4.5 ft/lbs. The torque wrench never clicked but the bolts seemed to be quite tight (and the last one snapped).

I don't want to have to go through the whole drain/refill/buy new gasket if I can help it. I will replace the broken one, but will the other bolts being over-tightened cause damage down the line?

So have you undone any yet to see what they are torqued to?

That REALLY should have been done straight away.

4.5ft/lb can be done with a 1/4 drive ratchet & is really very low, if you have sheared a bolt you are clearly going to be way over the elastic limit of the bolts.

I would be changing the lot, it is definitely not worth the risk of losing containment of the sump at speed on a motorway.

[Captain Answer]

All bolts out, new gasket, new bolts is what I would now be doing - sounds like you've got some quite tight bolts in there now, Im guessing it was a 3/8 or 1/2 torque wrench so you'll have got some good torque on them

Tho tbh for 4.5 ft lbs I wouldn't have bothered getting out the torque wrench

[InitialDave]

If it's not leaking, I'd probably just leave it as is.

[finlo]

If they're way overtightened cold expansion could be the final straw for them when it gets up to temp possibly?

[Paul_M3]

E-bmw said:

belfry said:

Paul_M3 said:

What was the torque wrench supposed to be set to, and what was it actually set to?

They are supposed to be torqued to 4.5 ft/lbs. The torque wrench never clicked but the bolts seemed to be quite tight (and the last one snapped).

I don't want to have to go through the whole drain/refill/buy new gasket if I can help it. I will replace the broken one, but will the other bolts being over-tightened cause damage down the line?

So have you undone any yet to see what they are torqued to?

That REALLY should have been done straight away.

4.5ft/lb can be done with a 1/4 drive ratchet & is really very low, if you have sheared a bolt you are clearly going to be way over the elastic limit of the bolts.

I would be changing the lot, it is definitely not worth the risk of losing containment of the sump at speed on a motorway.

I'd agree with changing the lot, but then I am an over-cautious engineer! The fact the one has snapped means that they will all be close to the limit if you applied the same torque to all.

It's highly likely that nothing will happen, but the consequence if they do fail could potentially be significant. I wouldn't be risking it.

[belfry]

Thank you everyone for your advice. We ordered new bolts and replaced them all (one by one so as to avoid disturbing the gasket). They are now all torqued to spec. The broken stud was easy to remove with a reverse drill bit and extractor.

OCD now somewhat relieved!