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

[Wotname]

Originally Posted by vmattiola

......
Hull is quite clean (although I was the one who cleaned it), and sail drive/ prop very barnacled. I was freezing tits cold and wimped out after a few mins of trying to scrape barnies off the prop. There are still some on the prop blades itself. Could this cause enough drag?

.....

YES YES YES

[vmattiola]

Originally Posted by Wotname

It would be great to know how the engine performed in the past at WOT in a flat calm.

I wish I could tell you, but this is a delivery and I've only know
the vessel for 8 days....

[vmattiola]

Sounds like I'm also gonna need to have a couple shots of rum and jump back underwater in my skivvies to do some more prop cleaning

[undercutter]

Originally Posted by Wotname

I don't disagree with you however, the OP reports 3200+ rpm at no load WOT. I am not sure how much the "+" really means so I take it the engine reaches close to max rpm at WOT unloaded.

The OP reports 3.2 kts max speed with flat clam conditions; without looking up the tables, I reckon you need maybe 8 hp max. to achieve hull speed for a 31' in a flat calm so 3.2 kts should only need say less than 6 hp. To have a fuel restriction to reduce engine output to 6 or so hp, it would have to be severe.

That said, I do agree the absence of black smoke does suggest a fuel restriction.

It would be great to know how the engine performed in the past at WOT in a flat calm.

Yes not enough prior history.

Where are you Wotname. We are anchored in Sandy Bay. Gusting to 40kts. Won't sleep tonight, lol.

[undercutter]

Originally Posted by vmattiola

Sounds like I'm also gonna need to have a couple shots of rum and jump back underwater in my skivvies to do some more prop cleaning

It might be worth changing those primary filters if you have spares on board and trying running the engine out of a pail of fuel fed to the lift pump. At least this would eliminate the tanks, piping, and racer filters as well as the primaries.

Worth cleaning the prop for sure but I do not envy you.

[Wotname]

Originally Posted by undercutter

.....

Where are you Wotname. We are anchored in Sandy Bay. Gusting to 40kts. Won't sleep tonight, lol.

At home with the fire going -all cosy! Boat nicely tied up in Port Huon.

Don't sleep, solve the engine and electrical problems of others between gusts

Anyway Sandy Bay has good holding and good protection....but I wish you safe night regardless

[Wotname]

Originally Posted by vmattiola

Sounds like I'm also gonna need to have a couple shots of rum and jump back underwater in my skivvies to do some more prop cleaning

Yep, this HAS to be done - sorry!

Until the prop is clean, there is simply no way the engine will perform to specs.

Clean prop, clean hull, clean (and sufficient) fuel, some air and compression are the only requirements for a marine diesel engine. Remove any one of them and bad things happen

[Pete7]

I would also have a look at the exhaust elbow on the engine, they clog up quite regularly.

Pete

[undercutter]

Originally Posted by Pete7

I would also have a look at the exhaust elbow on the engine, they clog up quite regularly.

Pete

What other symptoms would the engine exhibit with this problem?

[Cadence]

You may want to remove your fuel fill cap and run it just to eliminate a partially plugged tank breather. Quick and might save you a lot of grief.

[skipmac]

Always try the simplest, easiest (even if it might be the coldest and wettest) fix first.

I moored in a high fouling harbor for a couple of months and grew just a few barnacles on the prop. It was maybe 10-20% covered with small to medium sized shells. Cut my speed from 7.5 kts to about 3 kts. Cleaned the prop and was back to normal.

Clean the prop, test it out and if that doesn't fix it start trying the other ideas.

[sailon46]

Put clean fuel in a bucket and take fuel line off the tank put in the bucket and at the dock check it out if it doesn't persist make sure your vent to the tank is not linked.

[Brewgyver]

Originally Posted by undercutter

What other symptoms would the engine exhibit with this problem?

Good question, though I suspect you already know the answer, Undercutter. The engine would likely be overheating, though with cold enough raw water it might not be obvious.

[Djarraluda]

If it is the Volvo 2002 with a manual stop, check linkage
I believe throttle is a rocker bar with the stop and if stop is not absolutely fully home then throttle can not open enough
Could be fouled by gear cable and not going fully over
Roger

[MarkJ]

Originally Posted by vmattiola

sail drive/ prop very barnacled. I was freezing tits cold and wimped out after a few mins of trying to scrape barnies off the prop.

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.