Exhaust manifold nuts keep coming loose

[blackmav]

I have a patrol with turbo petrol motor.
Cast exhaust manifold. Has like a spacer plate between manifold and engine.
Manifold has been decked flat.
Nuts keep coming come loose.

Loctite? Gets bloody hot in there.

[Patroler]

If theyre bolts i'd run spring washers, be a bit careful if screwing into alloy, something like a keensert or helicoil would make the thread in the head stronger if you stripped it, i know loctite will break down with a flame, i'd check to see how high a temp it can handle.
I thought the manifolds ran studs and nuts? - if that was the case i'd just use glenlock nuts, theyre like a nyloc but use a steel insert to withstand a higher temperature, and as the name suggests are made by James Glen.

[THE 109]

Try some nordlock washers,they require 1.5 times the tensioning torque to undo.We use them at work in high vibration areas with good results and will handle the heat from your manifold.

[BadMav]

I have a patrol with turbo petrol motor.
Cast exhaust manifold. Has like a spacer plate between manifold and engine.
Manifold has been decked flat.
Bolts come loose.

Loctite? Gets bloody hot in there.

Loctite makes 2 high temp thread locker compounds, Loctite 2422 and Loctite 2620. Here's the write up...

Loctite 2422 and 2620 threadlocking adhesives are formulated to withstand heat and stress to 650 degrees F.

These anaerobic adhesives are ideal for use in industrial ovens, heat treatment operations, turbo engines, boiler rooms, refineries, pulp and paper processing, glass manufacturing, and metal fabrication processes.

Loctite 2422 is a medium strength threadlocker designed for applications where disassembly with hand tools is desired. High strength Loctite 2620 requires short-term exposure to temperatures over 650 degrees F in order to remove the nut and bolt with hand tools

[blackmav]

Thanks, good info.
Was a bit late when I posted, they are studs with nuts.

[blackmav]

Try some nordlock washers,they require 1.5 times the tensioning torque to undo.We use them at work in high vibration areas with good results and will handle the heat from your manifold.

These look like the go.

Gripping viewing http://www.youtube.com/watch?v=mgwmuZuJ02I

[BadMav]

Just watched the Nord-Lock video, they really do look impressive. Though I've seen a very similar demo with Loctite and had exactly the same results. I guess that's why they didn't show it in this demo.

[blackmav]

Would your average bolt/nut supplier keep these?

[awill4x4]

Would your average bolt/nut supplier keep these?

I just googled nord-lock and Coventry Fasteners come up as a supplier so it may be worth giving them a call.
Regards Andrew.

[nayto]

The Nordlock washers arent the best mate, i cant say iv ever seen them widely used. Some certain machines use them at work, and trust me the bolts still come loose. Ive never seen them used on an exhaust manifold though......
Anything to do with exhaust manifold or turbo mount bolts/nuts iv worked with just use Steel locknuts. Basically just a nut with the last thread distorted. Nothing works 100% but they do most of the time.
Also with the Loctite, im not sure if it'd work, i dont know what a petrol exhaust temp can get up to? but 650F (340C roughly) doesnt sound like much.

[Patroler]

glenlock nuts, theyre like a nyloc but use a steel insert

[sudso]

Use Stover nuts

[mkpatrol]

If theyre bolts i'd run spring washers, be a bit careful if screwing into alloy, something like a keensert or helicoil would make the thread in the head stronger if you stripped it, i know loctite will break down with a flame, i'd check to see how high a temp it can handle.
I thought the manifolds ran studs and nuts? - if that was the case i'd just use glenlock nuts, theyre like a nyloc but use a steel insert to withstand a higher temperature, and as the name suggests are made by James Glen.

Spring washers won't work, the heat re-tempers them & they flatten out.

To the OP, if the studs are long enough use a second nut and tighten them together. I used to do this all the time on troublesome exahaust components like Datsun L series engine pipe flanges, Falcon crossflow flanges ect.

[BundyRumandCoke]

You could always use a centre punch to distort the thread on the stud right where the outer edge of the nut is. Just enough to stop it undoing, yet not enough to wreck it next time you need to undo the nut.

[bazzle]

Loctite and spring washers will both be heat affected. Just use a 2nd jam nut and a flat washer if required on flange.

Bazzle

[blackmav]

Thanks fellas.
First thing to be done is new studs.