problem diagnosis needed, no speed, smoke, low rpms

[SloopJonB]

Originally Posted by jrd22

I would guess the max prop is stuck in the feathered position. Doesn't take much growth to keep the blades from rotating. My brothers Auto prop was stuck from non-use, had the same symptoms you are describing.

Wouldn't that behave more like the trans was in neutral? I don't understand how a closed prop could prevent the engine from revving up or cause black smoke.

[Faster]

Originally Posted by SloopJonB

Wouldn't that behave more like the trans was in neutral? I don't understand how a closed prop could prevent the engine from revving up or cause black smoke.

Jon it's a feathering, not folding prop... it could be stuck in a VERY coarse pitch condition, if not actually fully 'feathered'...

[thegreenflash]

I thought about the prop being stuck in the wrong position, I will check tomorrow.

[gbtillman]

If everything turns freely, check the turbocharger. When they fail the intake air can be restricted and I'm not sure for a Yanmar turbo but some are lubricated with the engine oil that can leak into the intake causing smoke and oil in the exhaust. I have seen a Cat diesel run away from an oil leak and overspeed even after the fuel was shut off.

If the impeller has failed you can also have pieces of it going through the intake valves and into the cylinders.

[Faster]

Originally Posted by gbtillman

If everything turns freely, check the turbocharger. When they fail the intake air can be restricted and I'm not sure for a Yanmar turbo but some are lubricated with the engine oil that can leak into the intake causing smoke and oil in the exhaust. I have seen a Cat diesel run away from an oil leak and overspeed even after the fuel was shut off.

If the impeller has failed you can also have pieces of it going through the intake valves and into the cylinders.

The engine runs and revs fine and clean in neutral.. that coupled with heavy loads and no 'drive' points to the prop, I'd say...

[LessTacksing]

Originally Posted by Faster

The engine runs and revs fine and clean in neutral.. that coupled with heavy loads and no 'drive' points to the prop, I'd say...

These responses are what I find to be the best of Sailnet...

David

[lancelot9898]

You know if it is in fact the prop being stuck in the feathering position, I'ld like to hear an explaination from max prop. ie...lack of proper grease, broken gear
I don't see how a barnicle could be strong enough to keep it from rotating, but you never know.

[MarkofSeaLife]

Originally Posted by lancelot9898

I don't see how a barnicle could be strong enough to keep it from rotating, but you never know.

The boat has had 5 months on a mooring in St Augustine. I reckon those barnacles may be oysters. I was there a month and my prop needed doing.

[Yamsailor]

Is your wet exhaust discharging normally? if not, then check the elbow on your exhaust manifold. I had the exact same problem and realized the wet exhaust was exiting the elbow because it had a hole in it. The water drained to the bilge instead of out the exhaust pipe.

Overtime the interaction of seawater and exhaust gases cause minerals and carbon to precipitate on the walls of the elbow. Eventually the elbow clogs (like a heart attack) causing the exhaust pressure to build up and blow a hole in the manifold. You won't get an overheat alarm because the raw water is doing its job cooling the engine. The reason you have low rpms may be due to a pressure imbalance between the engine and the manifold. Replacing the elbow will eliminate the problem if this is indeed the problem.


Good luck.

[thegreenflash]

Problem solved....It was due to growth, much more barnacles on the prop than I first thought, also the blades were not moving freely at all. The barnacles on the "hub" were preventing the prop from feathering correctly. 10 minutes in a wetsuit and it was solved, tachs up fine now with plenty of power. Thanks for the replies.
Steve