Low revs update

[Jobs_a_ good_ un]

Got a underwater camera at the weekend and checked the prop no dings no rope completly clear
Still finding one engine (yanmar 250,s shaft)still only acheiving 3400 rpm, port engine 3800 o.k
I spoke to the guy who done the service local yanmar agent he says he wants to think about it
He did a service about 2 weeks ago since then low revs on one engine starboard, prior to service both engines fine
Any Ideas please Help

 

[Wiggo]

Fuel starvation on one engine, almost guaranteed. Either blockages somewhere, or air being drawn in on the lift pump side.

Having said that, my luck would indicate that someone dropped a spanner into the throttle linkage and it's stopping it from opening up fully... ;-)

 

[Talbot]

If they were ok before the service and are not afterwards, there can only be one culprit, get the mechanic back to fix it and if they cant, get someone else and bill the first company.

 

[Bandit]

Cut a long story short.

I had dirty fuel problems port engine low on revs, cleaned filters.

2 of VP 63 on shaft 370 horses each.

I picked up a tarpaulin with both shafts.

Diver cleared both confirmed both props and shafts A1

I then got full revs on starb engine and 200 rpm short on port.

Port engine, Checked fuel filters many times , changed injectors, had fuel pump removed and checked, changed fuel line from tank to pump for hose still no difference.

Starb engine continued to pull full revs and ran smooth but speed down.

Some six months and many pounds later removed boat from water on first sight both props looked A1 on closer look starb engine blades bent back ie the prop had been reduced in pitch by tarpaulin and shaft bent.

Port engine , prop and shaft A1 but it was down on revs as it was doing all the work for the other engine.

Starb prop repitched and all ok.

Moral , Dont take a diver or someone elses work for it, you would not have seen this on a camera.

But in general just to settle your mind, if there is something wrong with your engine and the props, shafts gearboxs ok then its a fuel or air in fuel or fuel blockage or fuel pump or turbo or injectors or a dirty bottom. The boat's not yours.

 

[Jobs_a_ good_ un]

The Thing is the boat was fine before the service we came back from chichester at 3600 rpm on both engines then had the service done and the rpm dropped imediatley after that ,the mechanic wanted to pull the boat out of the water cost £180 before he even had a look hence the camera .
I could see both props really well and the rope cutters were clear as day I had a look at the shafts and could see nothing wrong there is no vibration and she goes up to 3400 smooth as anything
Im pretty sure he must have got a bit of muck or something in the fuel line when he changed the filters what do you think