[pleiad7]

This may be a stupid question, but it seems to be a recurring issue with Slynki's header bolts every few months. Right now she's sitting on ramps immobilized because of a nasty exhaust leak caused by a lost bolt and pivoting gasket where the header meets the cat section.

What do you guys use to keep the exhaust hardware in place? Loctite? If any such product is used, will it present a problem at a later time getting them to break loose when you want to?

 

[2.5x_sleeper]

Is that the attachment that uses bolts, springs & nuts?

Bobby...

['07 FSXT MODding Journal] ['03 X MODding Journal]

 

[pleiad7]

No, the ones with the springs are on the other end of the cat section. This is just a simple bolt tightened down with a nut.

 

[DFBrews]

Does torquing the bolts to different specs help? It might be different expansion rates of the materials stretching the bolts and causing them to work their way loose after a bunch of heat cycles.

 

[pleiad7]

It definitely has to do with heat cycling, expansion of the metals, and to some degree, vibration. I'm not sure if my hubby used factory torque specs when he installed the header about 6 months ago or if he just cranked everything gutentight. Should the nuts/bolts be staying put without thread locker when properly torqued?

 

[DFBrews]

It definitely has to do with heat cycling, expansion of the metals, and to some degree, vibration. I'm not sure if my hubby used factory torque specs when he installed the header about 6 months ago or if he just cranked everything gutentight. Should the nuts/bolts be staying put without thread locker when properly torqued?

They should thread locker is fine until heat is involved, heat is how to actually get the red loctite to release. When you guys repair it again I would inspect the bolts really close and see if they are stretched at all an easy way to check is get a nut with the same thread pitch and make sure it threads smoothly from top to bottom. If it where mine I would get new factory bolts and see if the torque spec is just foot lbs or torque to yield ie an initial torque plus a certain number degrees of rotation. Torque to yield offers a more uniform clamping force. most high stress engine components are torque yield in the diesel industry don't know if it transfers to Roo's

 

[pleiad7]

Good thinking on the new bolts in case they're damaged. We need to replace the missing one anyway so we might as well get both. I just looked up the torque specs for the nuts in the service manual and it's 22.4 ft-lbs. I'll make sure it's done right with a torque wrench this time!

 

[2.5x_sleeper]

I normally don't use a torque wrench on this type of fastener. I'd use lock washers. :wink:

Bobby...

['07 FSXT MODding Journal] ['03 X MODding Journal]

 

[DFBrews]

I normally don't use a torque wrench on this type of fastener. I'd use lock washers. :wink:

Bobby...

['07 FSXT MODding Journal] ['03 X MODding Journal]

After all the same heat cycles lock washers will lose their spring tension then they are just split flat washers:Banane37:

 

[bbottomley]

I tend to rely on rust, but it's hard to get there in the short term. Especially in the current California drought.

:icon_wink:

 

[jgrote]

After getting everything "gutintite", Take a hammer and a flat-head screwdriver and tap the thread closest to the nut so it bends slightly toward nut. Not so much that you will never get the nut off, but enough that the nut won't move. For a more permanent solution, a tack weld works well.

 

[Miniata]

I'd use something like this:
Metric prevailing torque lock nuts - Bolt Depot
An all metal lock nut that is non-reversible and often used in high temperature applications.

 

[pleiad7]

Yeah, rust is not usually happening here, and especially not this year. :lol: It's been a Death Valley kind of dry recently.

Jason, that trick sounds like it may be worth a try.

 

[CinderBlock]

Don't 2 normal washers = 1 lock washer? With 2 washers, you wouldn't lose the spring factor.

 

[jgrote]

I've done it thousands of times on stuff at work. It works well, costs nothing, and is undo-able. The trick is learning just how much to deform the threads so it works, but loosening it will straighten the threads out.

 

[DFBrews]

After getting everything "gutintite", Take a hammer and a flat-head screwdriver and tap the thread closest to the nut so it bends slightly toward nut. Not so much that you will never get the nut off, but enough that the nut won't move. For a more permanent solution, a tack weld works well.

I've done it thousands of times on stuff at work. It works well, costs nothing, and is undo-able. The trick is learning just how much to deform the threads so it works, but loosening it will straighten the threads out.

Staking is the term for this.

If you are deforming threads to get something to stay that is not designed to be staked aren't you in a sense masking the problem of improper torque?
I know I am sounding argumentative but in a dealership setting I see way to often people trying screwdriver on a thread to hold something "fixes" that can end up costing a serious chunk of change... A motor swap on a big rig can run in excess of 32k.

Try new bolts and 25 ft lbs of torque and see what happens, did the manual mention whether you lube the threads or install dry?