Newbie and Engine Smoke

[Scallywag10]

Hi all,

I’m new to the Rib scene and have a question about my Yamaha F50 outboard that I was hoping someone would be able to help with with.

I’ve taken her out a couple of times on the water and although she starts great every time, and I don’t notice any smoke initially. After i’ve run her for a while, the white smoke that comes from the back of the engine is quite noticeable. Just wondering if this is normal on these carb engines or not? Can’t say i’ve seen many outboards smoking? I have taken a couple of videos and uploaded them to show what it looks like after i’ve run it ashore for a couple of mins.

The videos are here:

https://youtube.com/shorts/4ab86Y4jD5M?feature=share

https://youtube.com/shorts/FnfYyhi2d6Q?feature=share

Any advice or help greatly appreciated. I was wondering if it were a stuck thermostat or water passages needed a good clean through meaning she’s creating steam but when I had her running for a couple of hours at the weekend in the water she didn’t overheat at all??

Many thanks

Laurence

[TmMorris]

Is it smoke or steam?

If white smoke then it's usually engine oil getting burnt in the combustion chamber because one of more piston rings has stopped doing its job.

If steam then it could be coolant water getting into the combustion chamber but probably just the muffs not giving a perfect seal and air getting sucked up and vapourised which wouldn't be anything to worry about.

First step though is to establish whether smoke or steam.

[Scallywag10]

Thanks for that. I think it’s steam but not 100% sure but I don’t think it’s to do with the muffs. This happened when our in the water but was a lot worse.

The oil in the sump seems to be in good condition and not milky or anything but it seems to be slightly above the upper oil mark. I wonder if this is forcing oil through? It’s only a few mm above the upper mark but could this cause this issue?

[TmMorris]

Over filling can lead to oil getting past If its smoke then it will smell quite clearly. It also hangs around longer than steam.

If steam then it could be from several sources. You'd expect some steam but that does seem a lot.

Personally, the first thing that I would do is comp test the cylinders and rule that out. While the plugs are out check those for being uniform and clean. Then measure the temp of each cylinder to check for one running hotter.

If all is normal there then you probably don't have any major issues and the question Id probably be asking is whether air is getting drawn in to the cooling system or whether some water is coming out.

Hopefully someone on here has the same engine and just confirm that this is abnormal for that engine.

[Miss Guided]

No smoke or Brown smoke - Healthy Engine

Blue Smoke - Oil burned in the combustion chamber - Blue smoke is never a good sign. The sooner addressed, the lower the risk of lasting damage Could be caused by: Wrong Oil. Excess Oil. Failure to change oil or oil filter regularly enough. Cylinder head – worn guide seals, valves or valve guides
Block – Worn pistons (pistons move 34km/hour, 26,400 times). Turbocharger – lube oil. Crankcase excessive pressure – breathers blocked

Black Smoke - Fuel High / Air Low (Unburned Fuel). Check/Clean Air filter. Fuel Injection Pump (FIP) Calibration. Turbo failure

White Smoke - Water, Timing, Injector Faulty Head Gasket – leaking water. Water in fuel

Grey Smoke = White + Blue Smoke. Fuel Timing Fuel Injection Pump (FIP) Calibration

MGx

[Milgrip]

Green smoke = Flatulence ?

[A1an]

what was the weather on that particular day?

On cold damp days I find that the engine steam is exaggerated.

On a dry summers day the steam seems to be less.