Revs and stern glands

[Guest]

My yanmar 2QM20 only revs up to 2200 rpm, shouldn't it go higher?

In the engine "room" there's a reservoir of thin oil with a tube feeding the propeller shaft. It feeds the shaft just in front of a piece of black rubber hose clamped with 3 hose clamps. At 2200 rpm water squirts/splashes in small drops out of the black hose, is this normal?

Also, all the oil (ca 200 ml) has been used after 4-5 hours running - seems a bit quick to me. Before I filled the reservoir with oil, water was flowing back up the tube from the prop shaft - i just poured out the water and filled the reservoir with oil, should I have done more to make sure the oil is getting down to the shaft?

Thanks for any advice

Paul

 

[LadyInBed]

It sounds like you have a bit of a leak in your stern gland.
Check:
-the rubber seal for snags/perrishing
-tightness of hose clamps
-prop shaft vibration at incremental revs
if it's vibtation it could be
-shaft misalignment
-worn shaft
-worn cutlass bearing at the prop end
it's a shaft out job to check for ware

God - I wish it would stop raining!

 

[dickh]

I'm fairly certain the engine should rev to over 3000 - check with your manual or speak to your local Yanmar engineer. This could be a fuel problem - blocked filters only allowing a low fuel flow - I had this when I bought my boat, couldn't figure it out until fitted a prefilter and water seperator and renewed the fuel hoses and discovered an automotive type in-line fuel filter in the fuel line - it was completely full of sludge. After fitting the prefilter it revved to 3000. Also check the exhaust water injection elbow - mine was completely choked with carbon last year and the engine would only idle - as soon as you revved up, black smoke poured out the back - check these items before checking injectors & fuel pumps(another cause of black smoke).
Is your 2200 revs under load or in neutral?
Your stern gland certainly seems as though it is knackered - I would expect the oil reservoir to last a full season at least.
Is there a manufactures name on the gland? it sounds like it could be a Vetus or similar gland.
Hopes this helps,


dickh
I'd rather be sailing...

 

[Twister_Ken]

Another cause of under revving is if the prop is too big for the engine - so called overpropping.

Because the prop works by cutting into water and forcing it backwards it encounters resistance. If the prop is too big (too big in diameter, too many blades, or blade angle too agressive - or any combination of the three) it can cause more resistance than the engine can overcome - rather like trying to drive up a steep hill in fifth gear.

However if that is the case, the engine should rev to full speed in neutral.

Certainly something is wrong with your stern gland - but I don't know enough about oil filled glands to know what to suggest. The 'normal' rate of leak through a stern gland is quoted as approx 6 drips per minute when running and one drip a minute when not.

 

[jfkal]

Does it rev higher in Neutral? If it does seems to be a prop problem (wrong size, barnacles). If neutral revs are low as well, check the fuel system and adjustment of the limiter.
You seem to have a Halyard(?) Dripless oilseal. There shoudl no water or oil leaking at all. Both fitting need to be connected to the oilreservoir. There is no repair on those things only complete replacement. I would do this rather sooner than later (. Make sure shaft alignment is okay before installing a new one otherwise you will ruin it in no time as well.

 

[Guest]

There are 3 seals in the stern gland which were knackered. I've replaced them, lots of water gushing in and all that. Now the stern gland is fine - but when taking out the propeller shaft the stern part of the coupling cracked and is now broken. Going to look for a replacement today, presumably too risky to have it welded?

2200 revs are under load, I don't know how high it goes in neutral, will test once the coupling's fixed and let you know.

Thanks for all your help

 

[Guest]

The engine goes to 3000 rpm in neutral - from your replies this implies a problem related to the propeller. Could it be anything else?