Honda 7.5hp - oil smoke.

[renns]

I picked up an older Honda 7.5hp outboard. It's in nice shape cosmetically, but hasn't been used in a while. I put it in a tank to test, and it fired up but smoked heavily at first. After a while, smoking seemed to settle down, but even after running for 15 minutes or more, it's still smoking a fair bit. A compression check shows about 150 psi on top and bottom cylinders. I'm wondering if anyone with experience with these motors might advise me of likely causes of the smoking. I have drained the oil out, and will replace with fresh and repeat the test. The oil that drained out was brown in colour.

I've done a bit of searching online, and have found very little information other than an owner's manual. Any hints of where to look next would be great.

 

[ahicks]

I don't have anything specific for you, but I can share that the bigger Hondas are picky about how they are stored. If laid on the wrong side they'll smoke for a while afterward (or leak everywhere). On yours, with that kind of compression, I'd take it out and run it for a couple hours. Maybe check your oil a couple of times in that period to make sure it''s not disappearing or mixing with water.

My bet is, it will slow down or stop smoking with some use.

 

[renns]

Thanks for the reply. I'm going to give it another run with fresh oil in the sump, and see if it settles down. If water does get in the oil, I'm assuming it would separate out if left to sit? The sump oil I drained out I've saved in a clear container, so I could check that.

 

[kdmiller8251]

If you get oil in the water you got big problems........Drain it and look at tearing that motor down........Oil / Water = Bad