Ford Lehman 120, Johnson raw water pump gasket

[GrandWood]

Servicing the raw water pump, I’ve put a new impeller in, and the gasket ya get is a wafer thin paper gasket.

Do you use the gasket dry or use some gasket sealer. When I removed the cover, didn’t seam like there was any sealer on it, and the gasket just peeled right off no problem. Wasn’t leaking or nothing like that.

Maybe double the gasket?

Thanks

 

[Nick F]

This gasket is used without sealer. Most tend to weep very slightly, producing green stains after a while.

If you use a thicker gasket this will make the rubber impeller be a looser fit against the cover with consequent decrease of pumping effectiveness. Whether this would be significant, I don't know (obviously depends on how much thicker).

There used to be a company (called Speedseal?) which sold a replacement cover plate with an O-ring seal embedded in it. This was a great improvement - no weepage and and no need to replace gasket when you check the impeller. (I had a machinist make O-ring covers for me. It takes some careful machining to cut the O-ring groove which has only a tiny space to pass between the inside of the pump body and the screw holes)

As a very minimum improvement, I change the screws to Allen screws.

 

[GrandWood]

This gasket is used without sealer. Most tend to weep very slightly, producing green stains after a while.

If you use a thicker gasket this will make the rubber impeller be a looser fit against the cover with consequent decrease of pumping effectiveness. Whether this would be significant, I don't know (obviously depends on how much thicker).

There used to be a company (called Speedseal?) which sold a replacement cover plate with an O-ring seal embedded in it. This was a great improvement - no weepage and and no need to replace gasket when you check the impeller. (I had a machinist make O-ring covers for me. It takes some careful machining to cut the O-ring groove which has only a tiny space to pass between the inside of the pump body and the screw holes)

As a very minimum improvement, I change the screws to Allen screws.

Thank you sir, much appreciated

 

[Comodave]

I put Speedseals on our last boat. They were great but alas when the founder of the company passed away his heirs decided to close up the company. Too bad it was a great idea.

 

[av8r]

I would strongly recommend switching to Allen-head screws. Get a couple about an inch long to use for starting, install the others, then replace the long ones. Get a few extras, and a couple of extra hex keys too, and keep them with the spare impellers.

 

[Comodave]

If I remember correctly the Speedseal came with thumbscrews which were pretty easy to tighten and loosen. On that boat one of the water pumps was really tough to get to, so the thumbscrews were nice.