engine miss firing

[MOBILEMERCMAN]

http://www.mercruiserparts.com/Show_...+Exhaust+Elbow

Install gasket with permatex aviation sealant on both sides. It has a brush in the cap. Scrape and clean surface. Drain manifold first. When you have removed riser you should see no signs of water or rust in center exhaust area. Tighten evenly to 30lbs.

[MOBILEMERCMAN]

Old thread on subject

http://www.seriousoffshore.com/forum...ead.php?t=3188

[drpete3]

http://www.mercruiserparts.com/Show_...+Exhaust+Elbow

Install gasket with permatex aviation sealant on both sides. It has a brush in the cap. Scrape and clean surface. Drain manifold first. When you have removed riser you should see no signs of water or rust in center exhaust area. Tighten evenly to 30lbs.

So this looks like an easy job. Where would you suggest I get the permatex sealant and also the gaskets? Looks like I have the cast type.

[CAPM KURT]

Good advice m.m.m. That's what I've used before is the Permatex. Just this week I've ben talking to Loctite just to try and get the best sealer I can as I'm fixin to change mine on my 3 year old 5.7liter that are leaking on the outside.

The Permatex is good to 400 degrees. I'm sure the exhaust gases are way up there but the actual metal surfaces are much lower, who knows exactly-maybe over 400 right on the edge of the exh side but way less on the water side.

I bought some Loctite Hi Temp Gasket Maker part # 30558, (good to 600F.) Put a bead out just to look at it-looks thicker like the old #2Permatex form-a-gasket but different smell and dried much quicker than Permatex so it's not just a similar product. Looks like it would work even better. It's non-hardening also. I'm going to try it next week or so.

Volvo Penta has just gone to thin metal gaskets with a crimped ridge in them. Cannot get the old paper type for my 5.7L from Volvo. I think I'll try one of the metal type with the Loctite 30558(even though they strictly say to put the metal one on completely dry) and one paper type aftermarket gasket. I'm just not sure about the metal type!

Do you have any experience using a gasket maker hitemp silicone on the elbows?? Loctite suggested it may work also(Loctite # 5920). Just have to make sure its a sensor safe one. But they aren't any higher temp than the 30558 - 600 degrees. Never heard of anyone using silicone. Probably not any better than the Perma or Loctite.

thanks for any advice

[MOBILEMERCMAN]

The permatex aviation is brown has the brush in the cap and is the equivalent to Mercurys Perfect seal. You should be able to find it in any well stocked supply house. I would not use silicone or any RTV.

[MOBILEMERCMAN]

http://www.smallparts.com/Permatex-A.../dp/B00137FW4S

[MOBILEMERCMAN]

Respectfully guys, I have witnessed the various gasket types, aluminum and stainless risers on cast iron manifolds over the years. You need to protect the metal around the gasket. Dry metal hazes and corrodes faster than protected metal. The foil gaskets were developed for SS risers on cast manifolds. They were just a band aid for poor engineering decisions.

I have been using perfect seal {aviation sealer} since 1983. There is nothing better.

It is just your engine at stake. Go ahead and experiment with something new.