Powerhead to lower unit gasket, 5.5 Johnson

[Buster]

 

I’m replacing the water pump on my 5.5 hp Johnson.  I’ve got the kit, including a new gasket for the powerhead to lower unit junction.  Would members recommend I use a gasket dressing (I’ve got Indian Head gasket shellac) or should I just clean both flanges and bolt these together with the dry new gasket (no shellac)?

This is an opinionated question but I’d like to hear your thoughts.

Buster

[bobw]

Yes, I use a gasket sealer on the powerhead base gasket, typically Permatex Aviation #3 sealer.   The Indian Head product should work fine.

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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Buster

[labrador-guy]

Everyone has an opinion!   For me, I coat that base gasket with oil when I assemble the powerhead to the leg.  These 5.5hp omc motors sometimes can be a problem getting the gearcase and water pump set up right.  Causing several power head removals.  If you use sealer you will need a new gasket every time you pull it apart.  JMHO

dale

[crosbyman]

never did use sealer myself…actually I reused the gasket if not  broken..  a small exhaust leak would not  matter much  and  a water   leak would drain down anyway.

up to you  but as JHMO  said !!      If you use sealer you will need a new gasket every time you pull it apart.  

Joining AOMCI has priviledges 🙂

[fleetwin]

I usually just coat both sides of the new base gasket with grease…  Can’t hurt to use sealer though, but it should be relatively light/thin, no need to make a mess and plug up passages

[Buster]

Crosbyman,

I like your rationale.  I’m going with no sealer.  A small leakage here would be hardly noticeable and it would make a subsequent removal much easier.  Though I intend to have a perfect assembly the first time, it doesn’t always work out that way.

Buster

[Tinman]

I’ve never used a sealer and never had any problems.

[aquasonic]

fleetwin wrote:

I usually just coat both sides of the new base gasket with grease…  Can’t hurt to use sealer though, but it should be relatively light/thin, no need to make a mess and plug up passages

I used to use gasket sealer, but after destroying countless base gaskets that were installed with gasket sealer, I now use just grease. By using grease, you will most likely be able to reuse the gasket next time you remove the powerhead. Don’t use anything harder than aluminum to clean the mating surfaces to avoid scoring them.

[Buster]

Antique Outboard Friends,

As an addendum to this project, I was curious about the water circulation pattern on these engines.  The bulk of the cooling water enters on the throttle side, circulates through the power head and exits on the shifter side.  I did notice a small, machined passage, shown on the attached photo.  This would allow a small amount of the return water to exit into what I’ll call “shaft alley”.

Can anyone tell me the purpose of this feature, as it applies to the water circulation scheme?  I’m continuously impressed by the smart design features of these ’50’s vintage engineers in their products.  Slide rule guys knew their craft.

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fleetwin

[fleetwin]

Most likely there to add a bit of a spray to the upper exhaust are in the housing to help keep that cool.  Although I’m wondering why it seems to be directed towards the driveshaft.  Your driveshaft splines are lookin kind dry, better remove the seal assembly, check for proper orientation, replace the oring in the carbon seal and the round gasket up top…

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Buster

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