Small amounts of oil at my exhaust

[jerseyboy]

I just launched for the season and saw some oil sheen coming from each of my exhaust upon start up, I checked before launch and oil levels were good and my oil pressure was 40 at 1000 rpm and temps were 180 on each engine. I have 8 53 Detroit's naturally to asperated. Once docked and engines shut off they continued to leak a little sheen and eventually stopped. The boat sat on the hard for 6 months and both engines were winterized. Could it be unburned fuel? Any ideas would be grateful. Thanks,

 

[madhatter1]

Most likely diesel sheen/and/or oil bypassing rings. Warm em up and run em. Bet it goes away. Until you put a little time on them too early in my opinion to troubleshoot. Assuming they run fine of course.

 

[rsmith]

It’s a bad injector I had the same and didn’t go away until I had them rebuilt.

 

[Captain Ralph]

Any smoke? Maybe white or blue? Any smell?
Could be an injector, but both engines, IMO, settled fuel or oil.

Fresh impellers,, What lube was used here?
Winterized,, antifreeze used for the raw water plumbings?
Winterized,, oil fogged at last shutdown?

IMO, run them for a few hours under load and check on them the next morning.

 

[jerseyboy]

Starboard engine went through a complete rebuild last year and had the port engine checked thoroughly. We ran the boat from it's winter storage across the bay at only 6 or seven knots for about an hour before we reached the summer slip 2 days ago. Should I take her back out and run her up to 13 knots for a while and see if it clears. If it is a bad injector
will that do any harm? Capt Ralph can you explain what you mean by settled fuel. Both tanks were filled last year and each still have 3/4 left. Also no smoke or smell.

 

[Captain Ralph]

Capt Ralph can you explain what you mean by settled fuel. Also no smoke or smell.

I'm sure there is a better term for this but nothing came to mind.
Fuel/oil may puddle in the air box or in a low spot in the exhaust manifold.
This may turn into a paste/tar and take some heat to burn away completely.
Fogging oil. if applied, may do the same thing.
No smoke or smell almost eliminates this theory.


Your not turbo, so a dry oil seal there is not an issue.

 

[Captain Ralph]

Should I take her back out and run her up to 13 knots for a while and see if it clears. If it is a bad injector will that do any harm?

Injectors can gum up while sitting. That's why I hate buying them off the shelf.
Usually the internal valve does not seat or close completely.
Idling around does build up some pressure but opening up the RPMs, under a load for a while builds up some more fuel pressure and cylinder heat / pressure.

Watch your exhaust for smoke but IMO, you can not hurt anything while water skiing next opportunity.

I'm not into snake oils, but a bottle of Marvel Mystery Oil in each Racor, has been known to clean up injectors.

If your still spewing a sheen, then call in your tech to find the leaking injector(s).

 

[cww]

Every time I’ve had this problem, usually accompanied by a “rich” smell that wafts up the back of the boat depending on the wind, it’s been a bad injector.

 

[Briankinley2004]

Also did you do any work to the raw water side of the cooling system while on the hard? I have had sheens from using penetrating oil in the processs of servicing anodes as well as replacing exhaust hoses. I once thought I had a stuck injector then remembered all the WD 40 I used to loosen and exhaust hose. It went away after a good run but stuck with me at the dock for a couple of start/ idle cycles.

 

[jerseyboy]

Thank you all for your comments and advice. I think I might try the Mystery oil and then take her out for a run. I now think the very small amount of sheen may be coming from just the starboard engine. Wind was blowing at about 10 to 15 mph and pushing the water around at the dock. I'll check again this weekend and see how it goes. Thanks again all.

 

[rsmith]

Injectors can gum up while sitting. That's why I hate buying them off the shelf.
Usually the internal valve does not seat or close completely.
Idling around does build up some pressure but opening up the RPMs, under a load for a while builds up some more fuel pressure and cylinder heat / pressure.

Watch your exhaust for smoke but IMO, you can not hurt anything while water skiing next opportunity.

I'm not into snake oils, but a bottle of Marvel Mystery Oil in each Racor, has been known to clean up injectors.

If your still spewing a sheen, then call in your tech to find the leaking injector(s).

Back in the 90’s people were putting this Pro-Long stuff in their aircraft engines. Naturally not FAA approved or sanctioned but neither is Marvel which has been rumored to have been used since the airmail days. Aviation Consumer which was a consumer reports type publication did an analysis on all the leading “snake oil” additives. They had a lab do a complete analysis on the chemical composition of this stuff. The Pro-Long was supposed to coat your engine with Teflon which turned out to be total BS. It was gear oil and grafite. But Marvel turned out to be no more than dyed and scented kerosene.
It’s like my friend who is head of clinical trials for a major drug company says 50% of the people taking the placebo report positive results

 

[rsmith]

Just FYI if it doesn’t go away soon fix it. I had a bad injector some years ago would smoke at start up then clean up. I had a busy charter schedule and couldn’t put the boat down for maintenance. Ended up burning a valve from the carbon buildup. Don’t wait too long.

 

[edward]

Went to a Marvel Mystery Oil sales meeting 50 years ago ,the salesman was there expounding on how great MMO was . Someone asked him would it ever hurt an engine . He rummaged around in his bag a produced a shot glass , poured a shot glass full and drank it down !! He was still vertical when I left . Maybe he made a trip to the head , , certainly put his money where his mouth was !!