Topic: Paper thin gaskets – Antique Outboard Motor Club,Inc

This topic has 19 replies, 10 voices, and was last updated 1 month, 1 week ago by The Boat House.

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September 20, 2024 at 8:51 am #290933
Tinman
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US Member
I recently purchased (2)base gaskets for my 1957 18 hp Johnson and 1 for my 1968 20 hp Johnson. These gaskets are paper thin and tear so easily. The thickness makes me wonder if they will even seal well. I ripped apart the 20 hp gasket trying to install the power head. It was a mess. And I was trying to be very careful but with something as thin as notebook paper almost it’s impossible not to tear it. All these gaskets were bought at marine engine. Why so thin???? And now I’m thinking of making my gaskets so my question is what is the correct material and thickness to make some base gaskets? Thanks. Bryan.
September 20, 2024 at 10:37 am #290942
crosbyman
Participant
Canada Member - 2 Years
no expert but those gaskets just seal the water passage and exhausts shot down the lower section . In either case I doubt they are subjected to high pressures

why so thin… cost cutting possibly delicate… depends how you reassemble things. why not “set” it down with some thin gasket maker just to keep it from being moved around while you settle the PH down before bolting it up.

Joining AOMCI has priviledges 🙂
September 20, 2024 at 11:16 am #290950
fleetwin
Participant
US Member - 2 Years
Did you use OEM or aftermarket gaskets? I have never seen one of those OEM base gaskets that was “paper thin”
September 20, 2024 at 2:00 pm #290956
Tinman
Participant
US Member
Bought them from marine engine. 304588. Says it’s original. Just flimsy.
September 20, 2024 at 2:01 pm #290957
Tinman
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US Member
Going to have to be very careful in the future for sure.
September 20, 2024 at 9:29 pm #290959
bobw
Participant
US Member
I’ve never had new gaskets that were as thin as what you describe. When I only needed a single gasket like a base gasket or head gasket I’ve usually ordered them off Ebay. When doing a complete powerhead rebuild, I’ve typically bought a complete gasket kit from Vintage Outboards. Never had any issues with either source. Doug at Vintage Outboard also offers individual single gaskets if that’s all you need. His gaskets are very good quality.

Bob

1937 Champion D2C Deluxe Lite Twin
1954 Johnson CD-11
1957 Evinrude Fastwin 18
1958 Johnson QD-19
1958 Johnson FD-12
1959 Johnson QD-20

“Every 20 minute job is only a broken bolt away from a 3-day project.”
"Every time you remove a broken or seized bolt an angel gets his wings."
September 21, 2024 at 7:01 am #290969
Steve D
Participant
This is what I think happened based on what I see in the manuals and previous explanations (from Frank R. I think)

They started out with a single thick gasket, then “OMC came out with a baffle kit (and 2 thin gaskets) to shield the crankshaft area from the exhaust and water/steam on the troublesome motors. It did very little good.”

By 1968 they started using a spacer (18-20 HP) to isolate the driveshaft and seal to basically attempt to do the same thing. At that time they went back to using a single thicker gasket and no baffle.
September 21, 2024 at 7:04 am #290971
Steve D
Participant
Previous post got critical error and 2 pictures didn’t load…trying here.
September 21, 2024 at 7:43 am #290975
Steve D
Participant
Try again
September 21, 2024 at 9:21 am #290978
bobw
Participant
US Member
Here’s a pic from my 1957 Evinrude 18hp rebuild showing the 2 base gaskets and baffle plate. Tinman – enlarge this picture and see how these compare to what you have.

Bob

1937 Champion D2C Deluxe Lite Twin
1954 Johnson CD-11
1957 Evinrude Fastwin 18
1958 Johnson QD-19
1958 Johnson FD-12
1959 Johnson QD-20

“Every 20 minute job is only a broken bolt away from a 3-day project.”
"Every time you remove a broken or seized bolt an angel gets his wings."

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Tinman
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