Heat Exchanger Gasket Sealing & Exh Manifold Question

[neildeb2]

Good January morning from the PacNW, all! Has anyone found a sealant or something that will seal the raw water-side gaskets on either side of the heat exchanger box? My DD 4-71Ns had the heat exchangers cleaned and the gaskets replaced 2 yrs ago by a very experienced DD guy, but within 18 months or so I could see the salt blooms beginning to seep out at the top and sides of all the gaskets. On certain gaskets he used a red substance on them that stayed sticky for months, and on some he used red RTV, but they all eventually seeped. Any success stories out there? 2nd question: I decided to remove and inspect the exhaust manifolds and piping since I don't know when they were last inspected. What a messy job. Exhaust wrap is not a fun thing to work with. As for the manifolds, it's near impossible to see inside well enough to determine if there's any corrosion that would warrant replacement. They only have coolant flowing there them, not raw water, so I'm wondering if there's a body of experience/knowledge to say exhaust manifolds should be changed every x years. Any thoughts?

[omecojh]

i was told to flush the cooling system with Cascade detergent every year or two.

[Captain Ralph]

Real DD gasket and grease.
Stainless screws and TefGel on them.

15 years on my stb HE still dry.

[neildeb2]

I have the DD gaskets. Are you saying you apply grease to the gaskets?

[Captain Ralph]

I have the DD gaskets. Are you saying you apply grease to the gaskets?

yes.
Old DD guy made me build everything with grease as the gasket dressing.
No glue.
Lately been using the same waterproof grease out-board/out-drives on water related surfaces like H/Es and water hoses. Not that I went out and shopped for it, just found several lost tubes of it a couple of years ago when moving my shop. Been using it up since.

It doesn't take much just to wet the gasket with the grease. The excess will flow out. years from now, it comes apart clean.
Grease on the O rings also.
Grease is not a gouge, scratch filler.
For rough surfaces, A good inventory of big fat flat files do wonders.
Or maybe a 1/2 sheet sander.

The must have of any sealing surface, flat, smooth & clean.

If you can't clean it up with a file, Loctite 515 fixes rough surfaces.
It will never come apart again.