Raw Water Gasket Sealants?

[Juliet 15]

Has anyone found a sealant or something that will seal raw water-side gaskets? My DD 4-71Ns had the heat exchangers cleaned and the gaskets replaced 2 yrs ago, but within 18 months or so I could see salt blooms beginning to seep out at the top and sides of all the gaskets. On certain gaskets the mech who was showing me how to do it 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?

 

[Greg QS]

rtv red works great. The trick is install the gasket with the rtf. Tighten not to spec. . let sit 24 hrs. and tighten to spec.

 

[Greg QS]

This will fill any compromises in the mating surfaces.

 

[RT Firefly]

Greetings,
Mr. J. ANY RTV product has NO place on a boat IMO! Since it already has been applied I fear anything short of more RTV (which will fail AGAIN) is going to fail unless you can completely remove all traces of said RTV. VERY difficult to remove to the point where a proper sealant will do it's job.
I suspect the red "substance" the mechanic used hay have been something like this:

Permatex® Super "300" Form-A-Gasket® Sealant, 4 OZ - Permatex.

I've called Permatex technical support in the past and they've been helpful.

Contact - Permatex

I'm sure they're quite familiar with DD's.

 

[Greg QS]

ok everyone has their opinions I guess?

 

[heysteve]

On certain gaskets the mech who was showing me how to do it 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?

The red, sticky stuff was probably Permatex High Tack gasket sealant. I've had good luck with it on water pumps.

 

[Jeff F]

Aren't they the same thing, essentially?

 

[heysteve]

Aren't they the same thing, essentially?

Permatex uses the terms "gasket sealers" and "gasket makers". The former is used to enhance a gasket seal, the latter can be used to replace a gasket.

 

[PM]

Next year I am going to try cutting a new cork gasket, a thick one, maybe 1/8 inch. Clean the surfaces and try it dry. I'm sick of scraping old gasket goop off the surfaces. There is really minimal pressure there.

pete

 

[heysteve]

Next year I am going to try cutting a new cork gasket, a thick one, maybe 1/8 inch.

If you don't already have a set, be sure to pick up a set of gasket hole punches. Makes a world of difference.

 

[Bmarler]

I have good luck with this sealant: https://www.napaonline.com/en/p/PTX...hyGvgpLkeCnc-6dlbgaAnJmEALw_wcB&gclsrc=aw.ds&

 

[TBill36]

I had the same problem with my 3208 gear cooler. Tried everything over the years and eventually leaked. Was sealing portholes with Butyl tape and thought - nothing to lose. Left the gasket out and just used the tape. Hasn't leaked in 2 years.

 

[RT Firefly]

Greetings,
Mr. h. I used to keep these on board. For larger holes I would just nibble around the edges.

About $15 or so...

 

[Juliet 15]

I have good luck with this sealant: https://www.napaonline.com/en/p/PTX...hyGvgpLkeCnc-6dlbgaAnJmEALw_wcB&gclsrc=aw.ds&

How do you remove that?

 

[Bmarler]

How do you remove that?

I use a gasket scraper and solvent. To be clear, I use it on seals or gaskets I will be replacing.
If you’re sealing rubber gaskets that you intend to reuse, I’d go with the earlier suggestion of a good rtv. I like ultra black rtv, and follow the advice to assemble it, but not torque it till the next day.

 

[capefearcruiser]

sealant

I agree with Bmarler, I was an auto mechanic for 40 years and have always done all my boat repairs. I have used Permatex Aviation Form-a-gasket for many years with good results. I found ATV was good for lighter duty jobs such as valve covers,ect.

 

[kehoff]

My favorite gasket maker/sealer was from Toyota called " FIPG" formed in place gasket , others have similar it is a type of anaerobic sealer

 

[Juliet 15]

Thanks for all the input and recommendations. I went with Loctite 518 gasket maker/gasket sealer (their words). I'll let you know in 18 months how it turned out....

 

[dutch-barge]

we use some 3mm thick bio fuel resistant rubber. which we cut on size. a sheet is cheap and use if for any kind of heavy gasket

 

[Jetstream]

Loctite 515 is what I use and have always been happy with. Just smear it on both sides of the gasket.

 

[RichardM]

I use Aviation Form-a-gasket on my 6V92s and it works great. Was recommended by a few DD mechanics…