4.3 Mercruiser Oil Slick

[saltlydawg]

I have 1990 Mercruiser Alpha one which I noticed was making a little oil slick behind the boat when I was backing into the slip. I am wondering if anyone has experience with this type of issue? I was thinking of removing the heads and having them reconditioned to see if it is the valve seals. Any advice is helpfull.

 

[Don S]

Re: 4.3 Mercruiser Oil Slick

Before you start randomly fixing things, why don't you start doing some testing first.
For one thing, if the valve seals were leaking it would probably smoke as the hot exhaust burns the oil. So I doubt you would see a slick from that.
Did you actually see oil, or just the rainbow and you thought it was oil.
Gear lube(drive) leaks, trim cylinder leaks, trim tab cylinder leaks could all cause oil. The rainbow if that is all you see could also be excess fuel from something as simple as a closed choke.

 

[Bondo]

Re: 4.3 Mercruiser Oil Slick

Ayuh,...And depending on just what you saw, it might be Perfectly Normal....

 

[saltlydawg]

Re: 4.3 Mercruiser Oil Slick

I saw what appeared to be oil but it could have been gear lube. Like I said I did not see it until I back into the slip and that was at teh end of the season. I will get it running on muffs to see what the exaughst looks like and check the gear oil.

Who knows maybe it wasn't my boat that created the slick. Let me get the starboard engine running and I will write back with my findings from the visual inspection.

 

[Gary H NC]

Re: 4.3 Mercruiser Oil Slick

A drop of gear lube will make a big rainbow in the water,
Mine did that last year just after servicing the lower unit.It was just a little gear oil that had dripped on the side when i filled it.I did wipe it down but the residue caused it.
I would drain the outdrive and look for any signs of water.Sounds like you may not have done that when winterizing last year.