5.7 manifold errosion

[cdavisdb]

Bill, thanks for the heads up. I'm aware of that issue, but most folks don't know that there are metals as well as graphite in never seize. I don't doubt that it could cause a problem in aluminum and stay away from it for that purpose. I used to use it on my volvo props, which are famous for sticking to the shaft. Never had a problem, but I use anti corrosion grease now.

[Bushwacker]

That's good advice, as the graphite is highly conductive and could increase galvanic action between aluminum and whatever more noble materials are in contact with it. Frank Brown, who was a well known Merc mechanic that used to crew for Carl Moesly on the race boats, used a mixture of anti-corrosion grease and Never-Seize on prop shafts and I've had good luck with that, but the mating parts are steel and brass/bronze, so no aluminum is involved. I normally use anti-corrosion grease on bolts, but Tef-gel would be a good choice for SS & aluminum combinations.

[cdavisdb]

tef gel is a new one on me. What's that?

[gofastsandman]

Teflon in a white gel form. Really sticky and gooey. I usually get more on me that what I am working on anyway. This should surprise everyone. Makes a nice barrier between dissimilar metals. Used it on my LP @ 7 years ago and no corrosion between ss and aluminum.

I recently learned about its conductivity properties. You can use it in butt connectors and such and add virtually no resistance. So I was told anyway.

Cheers,
GFS

[cdavisdb]

Well, I think its ok, I think. I've got a very long trip planned for next summer and this kind of "its ok, I think" can keep me up at night.

Pic below shows that the gasket doesn't cover the entire face of the head. The erosion was on the part of the head exposed and it appeared to stop once it got down to the gasket. I checked old and new gaskets, they cover an identical area, The outer two cylinder's exhaust show no issues, but I guess they run a bit cooler.

I think I will pull the manifolds next winter, just to check. . . . Maybe just before next summers trip would be a good idea. What can I say, I'm paranoid.

Anybody seen something like this before?


Opps, only took one pic and thought it was in focus, sorry. You can still mostly see that the gasket does not cover the area that was eroding.

[FishStretcher]

Judging by an image search, at the port-manifold face there is a lot of metal. Further in the port, say 1/2" or more towards the valve, the water jacket comes into play.


The two links below show how far you can and can't go. Although both seem to be seriously over ported to me. Gasket matching isn't a good basis for a template.

To me, your head looks ok. I think if it were a problem, then it would be a problem common to all marine vortec head equipped small block chevys. (I am assuming you have a vortec head. The internet seems to think so, too.)


http://www.pacificp.com/forum/viewto...c2a63762107ee9

http://www.justinb.net/bulletproof/page4.html

[cdavisdb]

Thanks Fishstretcher, just what I needed. Looks like I'm ok. I will pull the heads next year and look again, maybe grind the rough areas smooth, but not try to match the gaskets. Exhaust flow reversion is a buggabo that I worried about with the engine so deep in the hull.