I am replacing my 1.8L SS HEs with the OEM steel ones. I have two good HEs; I noticed the outer shell will slide about an inches fore/aft. A previous thread on this suggests sealing the ends of the shell with Red High Temp RTV to prevent heat loss and keep CO out

My question is when can the ends be sealed; can it be done before the HEs are installed ? or after installation ? Is there a reason the shells needs wiggle room ?

The SS ones will be looking for a new home......

Why the switch Jim?

I'd be concerned of using RTV with the outgassing. I guess once it is cured it should be okay.

I want a better seal at the heads; the OEM HEs have a better mating surface where they attach. Plus, at certain RPMs the SS HE create a tinny noise.

A little wiggle room might be for heat expansion. But, the HE tin connections to the fan housing can be a challenge. I wouldn't lock down with RTV until you have everything in place and properly aligned.

But really, I don't think you lose much air flow there. As far as CO.. there's positive pressure inside, so I wouldn't think you'd suck in ambient CO through that gap.

Good to know, thanks. I am still going to need some HE's sooner or later, just on the fence about stock units or SS

The metal on the SS HEs is pretty thin at the head end. It would be interesting whether a collar could be slipped over the ends so fitment was both larger and firmer

Pics of both below...

Thanks ! Hadn’t thought of that

Yep I agree and just got myself a set of Stock 2.0. HE's

They are better IMHO for more than the fit up and sounds. I think they emit heat better as well.

SS has a tendency to crevice corrode when overheated and cooled. This causes cracks. It also tends to expand unevenly if work hardened, furthering crevice cracking. There are work arounds to this and none of them are cheap.

I may still .....once I'm retired......tool the half shells just for the hell of it if no one else takes it on.

That's a nudge Mark......

I've used the Copper RTV Jim...seems to hold up if you are really concerned about it.

I know there are some very high temp items like tapes, gaskets,and packing material used for heat treat ovens that I have worked on. Some are more compliant than others and would allow for some expansion.

Thanks for the HE info, I guess I'll be sticking to stock units.

Those ends look nice Jim. I would'nt bother RTVing the the covers. You'll get plenty of heat. Plenty...

Thanks now that I've looked closer

My experience when switching from OE to SSI heat exchangers was a mild improvement in engine performance and faster heat. I don't know if they would put out more or less heat in total but the SSI heated up quicker. In California heat was not a big issue either way.

The SSI tubing is slightly bigger inside diameter compared to the OE 2.0L HEs, the outside diameter is the same but the tubing is thinner walled.
The thinner walled tubing and slight inner diameter increase, contribute to better exhaust flow. But also to the tinny noise Jim hears and less area on the gaskets.

Since I went from 1.7L OE exchangers to 2.0L SSI's the diameter change was a little more then if I already had 2.0L OE exchangers.

Jim