Bukh 20 stalling

[JustinT]

Hi all

What would be the reasons for my Bukh 20 to keep stalling? It only does it after running for a bit, once restarted it tends to idle ok. It's a bit hairy for approaching moorings etc and I have to go in dead dead slow incase I lose the engine.

[Searles]

Need more info e/g history type of controls ,wot has changed e t c .⛵️⚓️

[JustinT]

All are good questions. The boat has been idle for many years. Did a new oil filter, morse cable, and oil. Controls, not sure.

[tkeithlu]

Still not enough, Justin. It's being laid up suggests all sorts of problems.

Does it develop full power?

Are you using old fuel?

Any smoke?

Condition of the lift pump?

Idle set?

Air filter clean (remove all bird's nests carefully)?

Try taking it somewhere where you won't become the poster child for "Bonehead Boats" YouTubes, and run it a bit.

[JustinT]

It was laid up becase the previous owners used it as a man shed. I have spent the last year and a half getting it pretty sorted but for these remaining problems.
It seems to give full power, making 4 to 5 knots.
New fuel.
Some smoke, white not black.
Lift pump condition unknown and I probably need to service it.
Idle I am unsure where the setting is. It idles well unless it has been running for a couple of hours. Once it stalls and restarts the idle becomes ok.
Air filter, good point, I'll investigate it.
Ran it three days from Fort William to Lochcarron and it went very well.

[Compass790]

Tank vent clear? tank clean & pickup tube clear?
Air leaks is another possibility. Check every joint on the fuel system. air leaks can be frustrating to find

Without knowing yr vessel type 4-5 knots sounds too slow for a 28footer.
My late uncles 26ft full keel motor sailor used to do at least 6 knts cruising with the same engine.
We have an overpropped 26ft fin keeler & it does 4.5knts when the motor is only putting out 5hp at 2300rpm

If it's actually white smoke the injectors need a service, it should burn clean

[tkeithlu]

Generally, white smoke is not good news, because it is likely coolant, meaning a cracked head, block, or a blown gasket. The only exception is completely unburned fuel during hard starting on a cold morning.

Figure out your hull speed. In knots, it is 1.34 times the square root of your waterline length in feet. If your WL was 28' (it isn't) it would be 1.34 x 5.29 = 7.1 knots. Your engine should be able to push you at that or very nearly that without strain.

[JustinT]

The engine is water cooled.
Many have said it is likely the injectors.
I had it "serviced", but the guy failed to do a lot.
Going back in myself to have a go at a few bits, it's almost impossible to get paid experts to do it around here.

[Compass790]

Originally Posted by tkeithlu

Generally, white smoke is not good news, because it is likely coolant, meaning a cracked head, block, or a blown gasket. The only exception is completely unburned fuel during hard starting on a cold morning.

Figure out your hull speed. In knots, it is 1.34 times the square root of your waterline length in feet. If your WL was 28' (it isn't) it would be 1.34 x 5.29 = 7.1 knots. Your engine should be able to push you at that or very nearly that without strain.

His engine is raw water cooled & seawater or coolant ingress is steam but yes people could describe it as smoke & mostly do I guess.
Op should stick his hand in the smoke/steam & see if it smells of oil or diesel or just gets wet.
Yes agree it should do hull speed easy with a Bukh 20 if its developing its full power.
JustinT get yourself the workshop manual, it will pay for itself almost instantly if it's any good. I have not read a Bukh one to be fair.Here is link for free pdf:https://wiki.westerly-owners.co.uk/i...hop_Manual.pdf