Johnson Raw Water Pump Cover Screws

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catalinajack

catalinajack

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Joined
Nov 16, 2011
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Catalina Jack
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Defever 44
Okay, I give up. Searched this forum and Googled far and wide but could not find the size of the cover screws. I want to replace the slotted brass screws with allen head cap screws or thumb screws, anything other than slotted head screws. This would be for the pump on a Lehman 120.
 
I would pull a screw and take it a hardware store and match the thred. Most hardware stores have a gauge.
 
Like this.....?
 

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I replaced mine with cap screws from Ace Hardware. I purchased spares in case I dropped one I wouldn’t have to fish around to get back up and running.
 
catalinajack said:
Okay, I give up. Searched this forum and Googled far and wide but could not find the size of the cover screws. I want to replace the slotted brass screws with allen head cap screws or thumb screws, anything other than slotted head screws. This would be for the pump on a Lehman 120.
Click to expand...

What did you end up with? The size in the picture above are M5. The screws in my Johnson pump are M4 from my measurement.
 
Aren't the screws socket fit as well as screw head? I've never had a problem removing them with a little socket wrench. Plus the new impellers come with gasket or O ring and spare screws.
 
I took one of mine to Ace Hardware and bought a set of knurled head phillips head screws for my Jabsco RW pump and my Jabsco head. Both are now a piece of cake to service.

EDIT: I meant to say Allen wrench head, not phillips. The pic is right.

A2-70-Stainless-Steel-AISI-304-Hex-Socket-Knurled-Head-Cap-Screws.jpg
 
Last edited:
FlyWright said:
I took one of mine to Ace Hardware and bought a set of knurled head phillips head screws for my Jabsco RW pump and my Jabsco head. Both are now a piece of cake to service.

A2-70-Stainless-Steel-AISI-304-Hex-Socket-Knurled-Head-Cap-Screws.jpg
Click to expand...

Looks like Ace is the place :) although I think the Johnsons will be metric. So we shall see
 
sunchaser said:
Aren't the screws socket fit as well as screw head? I've never had a problem removing them with a little socket wrench. Plus the new impellers come with gasket or O ring and spare screws.
Click to expand...

Round with regular screwdriver.

I just bought an impeller and it did came with gaskets and o ring. Is it both or either / or?
 
The hardware store said that they were 8 x32. Only available in stainless with a hex head. See what happens when I get to the boat. Being a European pump you would think metric...but.
 
Being the pump was made for an English engine, they might have spec'd SAE fasteners.

Take an 8-32 nut out of the hdw store bin and fit it on your screw. And you can absolutely get 8-32 in socket head capscrew SS.
 
Ski in NC said:
Being the pump was made for an English engine, they might have spec'd SAE fasteners.

Take an 8-32 nut out of the hdw store bin and fit it on your screw. And you can absolutely get 8-32 in socket head capscrew SS.
Click to expand...

Exactly what I did. I got stainless hex head which is what I wanted. Surprised that they were SAE.
 
I forgot to mention they were SS. Right next to bronze on the metals chart so corrosion shouldn't be a problem should they get wet.
 
Screws are cheap.
Buy 6 of each of 8/32, 4m, 5m, 6m and any other size they might possibly be. SS cap screws if you can, or hex. toss the slot heads even if they come off OK. Keep the wrong size spares, they will eventually come in handy.
 
Easting said:
What did you end up with? The size in the picture above are M5. The screws in my Johnson pump are M4 from my measurement.
Click to expand...
Yeah, I saw that also and bought the metric size at a hardware having forgot to take along a sample. Wrong. They are 8-32's with a half-inch reach. I bought 14 socket-head cap screws. No more fumbling with those oft-disappearing slotted screws.
 
Easting said:
The hardware store said that they were 8 x32. Only available in stainless with a hex head. See what happens when I get to the boat. Being a European pump you would think metric...but.
Click to expand...


Try Mcmaster.com
I got some nice shouldered, knurled stainless ones for my pump. I can change an impellor in 5 minutes now..
 
I checked with the manufacturer first to see if I could use stainless screws and they said no problem. Then I took the brass screws to a local stainless screw provider and used those. Much better. No problems after two years. You can also chose the type of head you want.
 
It is a real shame that Speedseal stopped supplying their product - it was a genuine superior solution to this problem, as well as improved impeller life.
I believe you can get this size of machine screw with a large knurled head, in bronze, but I can't remember the supplier. :ermm:
 
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