Where to use gasket sealer??

Swell

Petty Officer 3rd Class
Joined
Aug 8, 2010
Messages
98
I'm rebuilding a powerhead and am wondering if it is necessary to use gasket sealing compound on any of the mating surfaces where a gasket is used? I've re-surfaced all the associated mating surfaces. I'm specifically looking at gaskets for:

- reed valve cover / plate
- head gasket
- exhaust gasket (to lower unit)
- carburettor to intake gasket
- driveshaft seal

To be honest I'd rather not use gasket sealer as it tends to result in the gasket being destroyed if removed again, but if it's necessary to achieve the appropriate seal then I will.
 

F_R

Supreme Mariner
Joined
Jul 7, 2006
Messages
28,226
Re: Where to use gasket sealer??

As a general rule, sealant is used on all gaskets---EXCEPT reed plate, intake manifold, anything to do with the carburetors or where it would foul a fuel passage. Head gaskets, depends on whether or not it has a pre-applied sealant coating. Do not add sealant if it does.

Also, use it on the outside diameter of all pressed-in seals.
 

Joe Reeves

Supreme Mariner
Joined
Feb 24, 2002
Messages
13,262
Re: Where to use gasket sealer??

(Gasket Sealers)
(Usually available at any reliable automotive parts type store)
(J. Reeves)

Do Not use any type of sealer on outboard carburetor or intake manifold gaskets as this would cause blockage of various fuel/air passageways. Also, there are new type gaskets, including head gaskets, which are used through out the engines that are coated with a substance that gives a shinny appearance to them. These gaskets are coated with a self sealer and are to be installed as is.... no sealers! Older style head and fuel related gaskets that are not coated with this substance are to be simply coated with oil.... nothing else.

All other gaskets (hopefully I've not overlooked anything above) should be coated with Gasket Sealer (the type that comes in a can that has a small brush in its screw off cap). This also pertains to some water pump installations that use a gasket between the plate and the lower unit housing.

Marprox Sealer 1000 or OMC Adhesive or Boat Armor Sealer 1000 (same substance)[See Below Note] should be used on any metal to metal or metal to plastic surface (such as impeller hsg to plate, and plate to lower unit surface) to eliminate air leaks. It should also be used on the Spaghetti tubing that is used on many powerhead crankcase halves, lower unit skegs, etc. I have found that this substance works quite well on various "O" Rings such as what are found on lower unit carrier and upper driveshaft bearing housings (Note that this substance is obviously not to be used on all "O" Rings). This substance also works quite well in sealing the surfaces between the lower unit and the exhaust housing to which it attaches, eliminating the unsightly water spray between the two after completing a water pump installation.

NOTE: OMC Adhesive is now Bombardier 3M Product #847 .

DO NOT use any sealer on the large "O" Rings that are used on the upper and lower crankcase heads (The housing/heads that slide over the top and bottom of the crankshaft). On those "O" Rings, use only a coating of grease.

The exception of surface to surface contacts pertains to the later model matching crankcase (block) halves (which does not incorporate spaghetti tubing) which call for "Gel-Seal", or any other surface that calls for Gel-Seal. This substance seals in the absense of air, and if called for, must be used. One other form of Gel Seal that can be substituted is "Loctite #518". Nothing else that I know of will do!

I advise against using silicone or permatex on a outboard engine. It simply will not function properly. The exception to this (as per OMC's recommendation), is to use the black Permatex (heavily) on the gasket 306242 which seperates the inner exhaust tube from the exhaust housing on the 1959 35hp and 1960 to 1970 40hp OMC outboards.

Thousands of parts in my remaining stock. Not able to list them all. Let me know what you need and I'll look it up for you. Visit my eBay auction at:

http://shop.ebay.com/Joe_OMC32/m.html?_dmd=1&_ipg=50&_sop=12&_rdc=1
 

Swell

Petty Officer 3rd Class
Joined
Aug 8, 2010
Messages
98
Re: Where to use gasket sealer??

Many thanks for the replies. Answers my question perfectly!
 
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