Volvo 19hp - max revs in neutral, but not while in gear

[Cadence]

Originally Posted by MarkJ

Stop all work on the engine!

Its not a fuel problem, nor injectors nor nuffin... except...

...

...da barnacles!

Get a wet suit on and do them properly or hire a diver. That prop must be, must be, squeaky clean.

I would have to agree. I don't know what a few barnacles are. If he was swinging a 24" prop with 190 HP a few might not make a difference.

[shakey doug]

Remove top from fuel lift pump, screen filter mesh might be clogged with crap.

[rhubstuff]

Barnacles on the prop? In my experience, THAT is your problem. Anything on the prop at all, even smooth algae and moss, destroys the hydrodynamic efficiency. Polish that thing before you do anything to the engine, which seems to be fine. Good luck!

[Duke Dumont]

We had the same problem on a 36' sloop which was parked at Gold Coast (Queensland) marina for about six months before the vessel was taken for a run however as soon as power was applied, there was no forward motion. Dived under to inspect prop and although it didn't look like that bad, as soon as it was cleaned (by hand) it was obvious that thrust was reduced by barnacle growth on prop (and hull).

[Wotname]

FWIW

One way to check prop if prop is fouled is to drive forward while tied up to wharf / jetty / pontoon etc and observe the prop wash. With rudder amidships and burst of throttle ahead, the swirl of the prop wash should appear when behind the transom in a tight line aft. The more fouled the prop is, the wider and less defined the swirl will be. In extreme cases, the prop wash will be coming out the sides of the hull rather than behind. Ask me how I know this

Of course it is subjective and varies between hull and prop shapes but it is handy to get to know how your prop wash looks when the prop (and hull) is clean. This gives you a yardstick to use in the future.

[Wotname]

Welcome aboard Duke D

[downunder]

Originally Posted by Wotname

What FS Mike said ++
Dirty hull or over propped comes readily to mind.

19hp is way more than necessary to move a 31' at hull speed in flat calm conditions so therefore the only problems must be:
1. Dirty hull and/or prop (ie excessive drag)
2. Wrong (or faulty) prop (unlikely but possible, especially faulty prop)
3.Engine not developing full power (again unlikely but possible)

I was thinking wrong prop also.

[Duke Dumont]

Cheers Wotname! Great site and lots of smart guys around to learn from. [emoji106]

[undercutter]

Originally Posted by MarkJ

Stop all work on the engine!

Its not a fuel problem, nor injectors nor nuffin... except...

...

...da barnacles!

Get a wet suit on and do them properly or hire a diver. That prop must be, must be, squeaky clean.

A few barnacles or even more growth would not prevent the engine from attaining full RPM. The prop would have to be so fouled that it would be overloading the engine. And if that was the case, then guess what?

You would have black smoke. :banged:


As the OP indicates that this is not evident then I highly doubt that this is the case. If I am proven wrong after the OP cleans the prop then I will gladly fall on my sword and endeavour to never offer advice on this forum again.

[undercutter]

Originally Posted by downunder

I was thinking wrong prop also.

A heavily over pitched prop will result in .....





You guessed it. Black Smoke

[skipmac]

Originally Posted by undercutter

A few barnacles or even more growth would not prevent the engine from attaining full RPM. The prop would have to be so fouled that it would be overloading the engine. And if that was the case, then guess what?

You would have black smoke. :banged:


As the OP indicates that this is not evident then I highly doubt that this is the case. If I am proven wrong after the OP cleans the prop then I will gladly fall on my sword and endeavour to never offer advice on this forum again.

Sorry cannot agree. I had barnacle growth on my prop and had the exact same symptoms as the OP; full rpm in neutral, limited rpm and slow speed in in gear and no smoke. Cleaned the prop and all the problems went away. This by the way has happened to me more than once.

Not saying 100% for certain this is the OPs problem but barnacles in my experience can give the exact symptoms he reports.

[vmattiola]

I'm just way too much of a wimp right now to jump in and clean the prop....we sail from Paros to Rhodes tomorrow, maybe the water will be warmer there!

[MarkJ]

Originally Posted by undercutter

A few barnacles or even more growth would not prevent the engine from attaining full RPM. The prop would have to be so fouled that it would be overloading the engine. And if that was the case, then guess what?

You would have black smoke. :banged:


As the OP indicates that this is not evident then I highly doubt that this is the case. If I am proven wrong after the OP cleans the prop then I will gladly fall on my sword and endeavour to never offer advice on this forum again.

Ummmm, really? Perhaps before being so extreme you could read what the OP says about the barnacles:

prop very barnacled.

So if the prop is very barnacled, as the OP says, are you really going to threaten to stop using the forum if cleaning it fixed the rpm issue?

I'd just clean the damn thing.

[Cadence]

Originally Posted by MarkJ

Ummmm, really? Perhaps before being so extreme you could read what the OP says about the barnacles:


So if the prop is very barnacled, as the OP says, are you really going to threaten to stop using the forum if cleaning it fixed the rpm issue?

I'd just clean the damn thing.

What's the fun of starting with the easy stuff? I think it is time to replace the main bearings.

[DaveSIM]

Davesim, several things. Not sure if this is a diesel or gas but assume from string it is a diesel. I'm assuming you have replaced the diesel filter and have no water in the bowl. A blocked filter will cause your issues. The other problem could be a failing injector or two. You'll have significant power loss but it will still idle. Injectors do not lay forever. Did you ever run out of fuel?? Could be air in the lines i.e. Needs bleeding. Prop needs to be clear of barnacles to function well and also sized properly. Good luck!! DaveS