I can't keep exhaust flange nuts tight

[matt schlicht]

I have a 2 liter that has 1.5 inch exhaust.  I have been fighting loose nuts for years!  I am sick of it!  I run the 8mm nut that takes a 11mm wrench.  Help!  What do you do to prevent this?

[Donny B.]

Hi Matt, I use the same hardware, but I use an thick washer from a head stud set and grind edge of it it to clear the header. Then I tighten it very tight and have been know to use loctite.  They don't come loose.  The washer distributes the load, doesn't distort and helps with keeping it tight.

[TexasTom]

I acknowledge your frustration.
Donny has a good idea and it's effective. If there's room on the stud, try putting an original (though new) wavy washer in between ... made the difference for me.
Good luck with it!
TxT

[matt schlicht]

Thanks for the help guys!  What loctite are you using?  I figured it was to hot of an application for loctite.

[Donny B.]

I use blue loctite.  Red is pretty final...

[Nico86]

I've had the same problem with the header/to muffler triangle flange, I use this now :

[deano]

I would think that part of the problem is that the exhaust gaskets are compressing with heat and age. Also, thin flanges could be an issue as well. I know some don't even use a proper gasket at all, and just use a hi-heat sealant..

[neil68]

A few years ago, I switched to the copper flange gaskets and the Bugpack 8/11 mm nuts and have had no issues since then.  The brass 8/11 mm nuts that I used to use, just weren't very strong, when torqued the threads would get damaged.

The Bugpack tall 8/11 mm nuts are silver in colour and take a lot of torque.  I also put anti-seize on the threads.  I've had my latest engine apart several times to change camshafts (experimenting) and the exhaust nuts are always tight now:

http://www.cip1.ca/ProductDetails.asp?ProductCode=C12%2D2512%2D20

[JS]

neil68´s solution also worked well for me.

[Mike Maize]

Same as Neil for me as well, both cars.I actually forgot how often they used to get loose until I read this!

[Donny B.]

I also forgot to mention that I use Vanagon exhaust gaskets.  They are a combination of metal and fiber and seem to work well for exhausts up to 5/8 in.

[Dave Galassi]

Donny, I found that to be the ticket on the gaskets as well.  The quality of the Vanagon gaskets is reallly good. 

I've also used (what I recall are) Rabbit copper exhaust manifold nuts (with the pinched tops to hold on the the stud) on my truck and recently found some cool ones to use that are originally on a 2004 BMW 7 series engine I took apart. They are similar to the Bugpack nuts but have what I think is a wider flange at the base.

[kingsburgphil]

I think you'll find most any new car with 8mm ex studs uses a metallic self locking nut. These nuts like their non-metallic self locking (nyloc)
counterparts lose their effectiveness with reuse.

[HERB]

The copper nuts that VW uses are actually copper plated steel with a 12mm hex, part #N..90894601. I've also used the Vanagon gaskets since 1984 with no leaks.

[Bruce]

With a 1½" tube, you don't need the 11mm OD nuts.  Use 12s or 13s.  The larger contact area will not damage the steel flange resulting in a loose nut. 
I use anti-seize, Loctite won't work at those high temps.

[Gunter]

for your info

http://www.csp-shop.com/products/22526

[Fiatdude]

I just "accidently" put a dab of high temp silicon on the threads before I start the nut onto the thread. It acts as a lubricant for installing the nuts and it cleans up very nicely with a small steel brush when you want to-- -- was shown this trick by an old guy way back in the 70's when I was drag racing my blower bike -- and that beast had enough vibration to loosen any bolt or nut LOL

[Peter]

Hey Harold,
can you tell us the partno of that silicone
I couldnt find it in the store

(need it for the exhaust)

Peter

[Harry/FDK]

Hi Peter, you might using this.

[danny gabbard]

Anybody try useing aircraft jet nuts ?

[Peter]

hello Harry,
its says max temp for a short time is only 300?
Jim talked about copper RTV some time ago?
or is it this product maybe?

[Kaferdog]

I've been using the 3/8 flanged nuts for 2 years and have had no problems..! if you can find the hardened nuts it would be better...!

[Type1/DVK]

Harry, that dirko cannot be used for hot exhaust nuts... 

[Dominick Luppino]

I just use the CV Joint washers, works for me, I also use them on my intake manifolds.

[Wout]

I've used copper nuts (special 12mm wide in stead of 13mm).

gr
Wout

[Fiatdude]

I just used the cheap clear silicon -- worked perfect, even as a gasket material -- It wasn't until I started super heating the exhaust with turbos did it start to fail -- Red stuff now

[Peter]

Whats the red stuff then Harold?

[jonas_linder]

This washer is the shit, you don't even have to torque the bolt down really hard.





www.nord-lock.com

[Fiatdude]

http://www.permatex.com/products/automotive/automotive_gasketing/gasket_makers/auto_permatex_ultra_copper_maximum_temperature_rtv_silicone_gasket_maker.htm

[Peter]

Thanks a lot !!