The use of Copper exhaust manifold Nuts?

[Maverik]

Hi folks,

So I've got my exhaust manifold off my Defender 200tdi at the moment, the nuts around the turbo where quite corroded so ordered some replacement, when searching for nuts I got quite a few hits with copper nuts.

Does anyone have any advice with using copper nuts on the exhaust manifold?, are there any benefits for me to fit copper nuts over standard steel ones? or reasons why I shouldn't use them?

 

Mav

[Inigo]

They were standard on my old Jag XK engine.  I seem to remember that the argument was to do with the heating cycle and that wouldn't loosen after repeated heating and cooling.

[Nonimouse]

Same as brass - don't corrode bond either

[Stellaghost]

Just be careful tightening up  I think they can strip the threads more easily being a softer metal regards Stephen

[David Sparkes]

1 hour ago, Stellaghost said:

Just be careful tightening up  I think they can strip the threads more easily being a softer metal regards Stephen

You will find that the standard brass nuts for this purpose are longer than the equivalent steel nuts, to help avoid this 'easy' fail point. The other trick is to only use a standard open ended spanner as this limits the maximum torque you can apply.

There are available on eBay UK 'double length' brass nuts, designed to cover all the exposed thread on the 'pipe to manifold' studs and so inhibiting corrosion of any exposed thread, which would otherwise damage the nut as it was forced over the corrosion.

These may not be suitable for your 200TDi application, but Paddocks sell Brass Nuts for the S2 and S3 range. I know the Paddocks search function can be a little trying but it's easy to find these, simply search for 'Brass'!!

 

Edited to add that the links already included will be for BS or UNF threads when I'm guessing the 200TDi is Metric.
This eBay supplier included the option of M8 and M10 nuts, which might be more suitable.

Regards.

Edited July 2, 2020 by David Sparkes
To include the Metric options

[FridgeFreezer]

As others said, brass nuts tend to be deeper than steel ones to avoid stripping threads, and they won't corrode or stick on.

For ultimate loveliness buy unequal thread studs - standard thread into the head/part and then a fine thread with matching brass nut for the other side.

[Maverik]

I just received the copper nuts, they're magnetic, so I presume they're copper plated. they look pretty durable so going to give them a try, worst case I guess is they don't stay tight so I'll just change them out.

I just wanted to check make sure i'd not missed something obvious with using them over the cheap galvanised ones.

[Ex Member]

Yes.  They are copper plated steel nuts.  Pure copper nuts would be a very bad idea....

Galvanizing does not work.  Zinc melts at 420 C, well below typical exhaust temperature.

Edited July 2, 2020 by Red90

[Romahomepete]

It is the exposed part of the thread that corrodes.  It is worth while if the studs are in good condition  putting double nuts on to cover all exposed threads, then you dont destroy the inner brass nut when undoing.

 

Peter

[mickeyw]

When I had my 2.25 petrol 88" I was always chasing loose manifold nuts until...

My local parts man who was an invaluable resource and walking LR encyclopedia could get all sorts of oddities for his customers. One of these was, as Fridge said, studs with different threads at each end. Course UNC into the manifold and a longer fine UNF section for the nut, in stainless. With these I used BZP a single coil spring washer and BZP steel nut. This provided good tightening capability and better resistance to loosening. 
Note: never use stainless nuts with stainless screws anywhere near an exhaust. They tend to gall and will be worse to undo than the most corroded mild steel equivalent.

The original LR design of a long brass nut seems good in that it doesn't corrode, and it doesn't leave any exposed stud thread to go all grotty, but I could never tighten them enough to stay done up for long. I think the brass nut was susceptible to too much expansion through heating and cooling cycles.

[Ex Member]

Brass and stainless steel nuts on steel studs are a bad choice for a hot applications as they expand more than steel, thus loosen in service.

The copper plated steel nuts mentioned here work well.

[FridgeFreezer]

My solid brass UNF ones haven't loosened in years of service, I must have done something wrong

[smallfry]

Ford used to fit copper plated manifold to downpipe nuts years ago, and they were a bar steward to get off after a while.

I have a huge tub of Rocol J166 anti seize compound which I have used with success, with like Coppaslip but much more durable.

[Maverik]

Probably came from the same people.

[Happyoldgit]

A lot of the 1930's stuff I've restored in the past have steel manifold studs in block and long brass nuts that cover the entire length of the stud, or two shorter brass nuts that do the same job. They would generally undo without issue even after decades of use - as long as the thread hadn't been pulled through over tightening.