Does stainless cause problems

[lewdon]

I recently fitted a water pump using Stainless bolts with copper anti-seize grease. I mentioned this to a group of friends which resulted in much sucking of teeth, sharp intakes of breath and anecdotal tales of disaster. These Included “I knew a man who used stainless bolts on his motorcycle crankcase and when he got up in the morning the bike had dissolved into a pile of white dust” and “when this blokes land-rover got caught by the tide the only usable parts left were those attached to stainless bolts by copper grease” (I may have misquoted slightly – my memory is a little befuddled as at least the conversation was well lubricated).
This made me curious, and I’ve looked on the internet but I cant find definitive answers, though I have learned that the Permatex data sheet for their copper anti-seize recommends it for spark plug threads in aluminium heads, that a number of aluminium alloys actually include copper and that 304 StSt is a long way from mild steel in nobility. What I have really found are lots of different opinions that seem to be based only on theory..
I know many of the people on here use a lot of stainless. Do you use StSt bolts in aluminium type alloys, does copper grease act as an electrolyte, does the copper in the grease react with the aluminium, or act as a sacrificial anode, and is copper grease conductive. So many questions, so little time, does anyone know any answers?
And the most important question of all - has anybody ACTUALLY had any real first hand personal experience of problems with StSt bolts or copper anti-seize grease?

[lewdon]

Thanks everyone; Most of my questions have been answered.

I have also been doing a bit more reading.
Galvanic cell voltages are;-
Stainless Steel & Mild/Carbon Steel = 0.5V
Stainless Steel & Aluminium = 0.58V
Mild Steel & Aluminium = 0.08V
Copper & Aluminium = 0.53V
Copper & Stainless Steel = 0.05V
Copper & Mild Steel = 0.45V
NACE recommend that in brine galvanic voltages should not exceed 0.25V, and in fresh water should not exceed 0.45V.

I was surprised that Stainless steel in Mild steel has a galvanic difference of 0.5V = very corrosive, whereas Mild steel in aluminium is only 0.08V = almost no galvanic corrosion. (Compared with Stainless steel in aluminium = 0.58V.)
I have not been able to find out whether the insulating jointing compounds recommended for dissimilar metals are able to withstand engine temperatures and oils.

But the proof of the pudding is that no one appears to have actually experienced any problems with Stainless and copper grease in Aluminium on our cars. So I shall leave my Stainless bolts in place.

[lewdon]

TurboTony said:

Having one on board a nuclear submarine would be a nightmare, especially if you are claustrophobic.

Not if you keep the hood down. (and the hatch open)