Thermostat housing fasteners

[alan.barker]

Good luck
Alan

[gus]

<<<Hi Tony.
I think you should be careful using stainless steel in Aluminium. They are a long way apart on the galvanic scale and in the presence of moisture can cause corrosion. I believe It is possible to use stainless but it needs to be isolated with a barrier cream. Way back we used to use Lanolin on outboard motors but I think modern materials will be better now.
Ordinary steel bolts cause a lot less trouble.
Best of luck
Eric in Burnley
<<

worry for not even a second about this
if you used aluminum bolts to hold together a SS cylinder head, perhaps after some years the bolts would be damaged, but outside of use in fully submerged salt water applications, there is no issue with this.

I changed all the screws holding various lenses etc to SS in 1984.
There is no galvanic corrosion
The SS rear silencer has hung on an aluminum bracket I fabricated for 25 years

Galvanic corrosion is a real thing, but it is so dwarfed by good old fashioned steel corrosion, that it is, for the purposes of our cars, irrelevant

[Craven]

My observations on the use of studs rather than bolts being used is where dissimilar metals are fixed together and the same thread type is less than optimal for both. eg UNC one end with UNF the other, exhaust studs are typical.

[ericbushby]

Thanks Gus, Your experience is useful. The problems I have seen were mainly industrial with long term exposure so may be irrelevant,
However it is still useful to be aware what problems can occur when choosing a different material. Sometimes the old tried and tested methods are still good. I would not change those studs to stainless.
Cheers
Eric

[gus]

As a rule anything in the engine bay of a Lotus tends to get enough oil on it that rust is not the primary problem....there are certain applications where the consequences of failure are so high[think aviation] that even a narrow risk of a problem is worth consideration.
My car has standard grade 5 bolts in this location, and again, has been so for 40+ years[54 really]