1990 Johnson 8 HP Exhaust Cover Disassembly Difficulty

[Derrick Fronckowiak]

I have a 1990 Johnson 8 HP. I'm taking apart the exhaust cover (had a broken elbow fitting that I couldn't get out). Anyways, the outer exhaust cover came off easily (six bolts and you're done). The stack up is outer exhaust cover-gasket-inner exhaust cover-gasket-crankcase. The inner exhaust cover (which is sealed to the crankcase with a gasket) wont budge, and I don't want to trash it by beating on it. I suspect it might be stuck to the crankcase due to age and corrosion. Lots of crud, scale, salt you name it that is blocking the water passageways, so I really need to get it off. It appears to be an obsolete part as I can't seem to find a replacement (another reason why I don't want to trash it during disassembly). Any ideas as to how I could get it off (tricks/tips)?

 

[interalian]

The elbow is up at the top, and is made of plastic, not sure why the cover needed to come off for replacement?

Having removed the outer plate without breaking any bolts is 90% of the battle. If you're going to continue, I'd soak the gasket areas in penetrating oil and try some gentle tapping between the plate and block using a thin tool like a putty knife (use the side of the blade and tap the opposite side).

 

[Derrick Fronckowiak]

Interalian-thanks. What you said makes sense. I'll give it a try (with patience!). As you mentioned, the elbow is plastic, so it broke off with very little effort. As I tried to drill it out, I got pieces of it that went inside and I couldn't get the threads cleaned out without putting more debris inside the cooling jackets. I didn't want that debris to cause problems (clogging) somewhere down the line. This all started because I couldn't get any water out of my tell tale. I have no regrets in having removed the outer exhaust cover as I found A LOT of scale, salt, crud, etc. that was restricting water flow through the exhaust cover (I'm convinced this has to be the first time it's been pulled off since it was built). Also, I got a buddy who recommended this Rust Remover (made by CRC). It's got a proportioner that you hook up in-line with the hose (like a bug or fertilizer sprayer), then the other end attached to the muffs. You put this solution in the little cup on the proportioner, turn on the water and run you motor for 2 to 5 minutes (or until that little cup is empty of solution). It's supposed break down salt deposits and coat the inside of your motor with some kind of protective coating. Ever hear of or try that stuff? I operate almost exclusively in salt water, so I need some better prevention that just fresh water flushing (especially on my older motors).

 

[interalian]

Nope. Never tried any flushing agents on any outboard, but I'm now a freshwater operator. My '82 90hp spent 3 weeks per year in the chuck and we just flushed it on muffs after pulling it out. Usually dropped it in a lake on the way back to Calgary to give it a proper run on fresh. When I took it apart after 33 years it was only a little crusted - nothing to worry about.

 

[Derrick Fronckowiak]

Interalian - your advice worked. Used the penetrating oil and a putty knife. Had to finesse it a little, but eventually the inner exhaust cover came off too. New seals and elbow on order and waiting for them to arrive. Thanks!!!!

 

[interalian]

Good stuff, glad you got it sorted. Working on these old motors is fun, no?

 

[Derrick Fronckowiak]

Yeah it's fun...and a little scary sometimes. Sometimes you open something up and look inside and you just know you are the first person to be in there since the engine was manufactured....like opening a time capsule....filled with corrosion, scale and salt deposits. But yeah...it's fun.

 

[Derrick Fronckowiak]

Interalian, I almost forgot to ask this. Do you know if there should be any kind of a gasket cement or sealer used on those exhaust cover gaskets? What I've seen used (and used myself) is the red and/or black RTV sealant. But I've also seen the yellow, gooey "elephant snot" type of gasket sealer used in various places on different engines. Just wondering what Johnson/Evinrude calls out for as these gaskets will be subjected to water/salt and exhaust gas exposure.

 

[interalian]

I use the OMC gasket sealer (elephant snot) on most of the gaskets. Light coat.

Don't like sillycone.

 

[Derrick Fronckowiak]

Sounds good. I'll go with that stuff too.