My nuts have crumbled

[Walrus]

I was doing an oil change at the weekend and noticed that some of the nuts on the stainless exhaust have crumbled, some to almost nothing.


Can you spot the difference between the stainless steel parts and the cast iron one?




You can see from the pics that the bolts appear to be ok. The cast knuckle is looking rather rusty but is till quite solid. It's not leaking (yet), but my question is should I attempt to remove & replace the nuts? The exhaust is still going well, even if it is a bit discoloured; its been on 5 years or more. If I do replace the nuts, what to replace them with? Stainless steel? Copper? Something else?

[itchyfeet]

My exhaust is steel but I have stainless nuts washers and bolts so they never rust.
Been like that for several years and the exhaust has come off and been reassembled twice in that time.

I would remove and replce with stainless nuts and washers, bolts are already stainless by the looks

[123-jn]

what you need is stainless bolts and solid brass exhaust nuts (slightly deeper)(and available in undersize 11mm AF as well as 13mm AF to aid fitting next to bent pipes) > There will be no rusting or galling then. (Apart fropm that nasty cast knuckle joint) somewhere I have seen a stainless version of that knuckle joint welded from tube, very tasty but also very expensive.