Heat Exchanger Fasteners

[Ferrino]

I cleanly removed my OEM Carrera heat exchangers recently and am unsure what the recommended replacement fasteners should be. I need to replace a few studs and then all of the barrel nuts and regular nuts (are these supposed to be locking nuts?). Some have recommended copper-based nuts before - is that a good idea? Thanks.

[kodioneill]

I'd go with stainless on all exhaust fasteners. I know you can't get stainless barrel nuts so I use a heavy coating of copper never seize (sp) on them.

[4flyboy]

Lucky California car owner Ferrino.....

[KTL]

Plain steel (zinc plated) nuts are fine. Not a big fan of the copper ones since they are easy to round off the flats if you can't get a clean grab on the nut with your wrench or socket.

The barrel nuts are still available if you want to replace with same. Pelican carries them. Or you can use an 11mm M8 nut and a thin wall deep socket to get the nuts up thru the exchangers. 11mm M8 nuts are not really common & you have to hunt for them. I found mine (I use them on the Weber/PMO manifolds) from CB Performance.

[redridge]

copper nuts, anti-sieze are fine... its only 17lbs of torque.

[HawgRyder]

I have always gone with stainless studs and brass nuts if possible.
They lock up nicely...and don't seize.
Bob

[Ramp]

How about OEM from Pelican ? If new and used with antisieze, shouldn't that be fine for the foreseeable future ?

[The cap'n]

Stainless steel studs are brittle and apt to fracture after heat cycling. Those "copper" nuts are plain old steel with copper plating. They're lock nuts, which Porsche NEVER used for this application on air cooled engines. OE hardware was fine when they installed it, and it should be fine now. If they broke when you took them apart, you didn't use the right/enough penetration oil and/or heat. 2.7s were famous for breaking exhaust studs, 3.0/3.2s aren't because Porsche moved the heat source farther from the problem area.

[Ferrino]

So just to confirm - the OEM nuts are not of the locking variety. I guess the corrosion is enough to keep them nice and snug :-)

[KTL]

The weight of the exhaust itself helps prevent them from loosening too. Honestly, plain zinc plated nuts with a blob of antiseize (the inexpensive Permatex is great stuff IMO) will do just fine. Lock nuts here are a PITA due to the tight access. You want to spin the nuts onto the studs as easily as possible! Also helps to run a thread cleaning die on the studs