Engine question

[Fredd]

I sea trialled a boat the other day and need a bit of advice on the engines .
It's a Princess 35 with Cummings 250 , it started on the button from cold , apparently hadn't been run in over a month , ran very smoothly. When we took her out it was force 3 , she accelerated well , up to maximum revs and max speed was 25.2 knots.
The owner said that she would normally achieve 30 knots but she has been in the water since last July so there is probably a lot of fouling on her .
My question is one engine was smoking a lot more than the other , it revved as easy as the other ,sounded fine and didn't seem to have any other problems . It was suggested to me by a friend that it might just be some extra fouling on the prop , but then again it could be a sign of a bigger problem and that as part of the survey there should be a compression test done on the engine .
The engines have a full service history and appear to be well looked after.
Any advice would be appreciated

 

[Portofino]

Fouling ,hull and especially props will cause the symptoms you describe .
If you are keen to proceed maybe at lift out ( surveyor ?) get it jet washed and 1/2 hours worth of acid clean the props .
Perhaps the seller for the sake of £5 quids worth of HCL- may well clean the sterngear it's in his interest @ survey you don,t reject .
If they still smoke excessively when "clean" then further investigation or make it clear you will walk away /adjust price etc.

 

[Piers]

An immediate start on a Cummins is always a good sign. You mention smoke - white or grey? Fouling is real possibility as stated above and the hull and running gear must be cleaned before you do a WOT (wide open throttle) check.

As an aside, what gearboxes are fitted?

 

[Fredd]

Fouling ,hull and especially props will cause the symptoms you describe .
If you are keen to proceed maybe at lift out ( surveyor ?) get it jet washed and 1/2 hours worth of acid clean the props .
Perhaps the seller for the sake of £5 quids worth of HCL- may well clean the sterngear it's in his interest @ survey you don,t reject .
If they still smoke excessively when "clean" then further investigation or make it clear you will walk away /adjust price etc.

I'm after getting a surveyor organised , the boats in Spain and I'm back home so he's going to arrange with the owner to have it lifted to check the hull and he'll have a look at the stern gear.

 

[Fredd]

An immediate start on a Cummins is always a good sign. You mention smoke - white or grey? Fouling is real possibility as stated above and the hull and running gear must be cleaned before you do a WOT (wide open throttle) check.

As an aside, what gearboxes are fitted?

The smoke was quite black when the engines was under load and worse on one side . I was told the boat was used only every few months . As to the gearboxes ,I don't know what is fitted but apparently one gearbox was replaced 2 years ago at a cost of €5000. They have used a main Cummins agent to do the servicing on her for the past 10 years or so.
It was shown to me by the owners son who uses it only occasionally and that his father was unable to use it anymore so it is left idle most of the time now.

 

[Piers]

The smoke was quite black when the engines was under load and worse on one side . I was told the boat was used only every few months . As to the gearboxes ,I don't know what is fitted but apparently one gearbox was replaced 2 years ago at a cost of €5000. They have used a main Cummins agent to do the servicing on her for the past 10 years or so.
It was shown to me by the owners son who uses it only occasionally and that his father was unable to use it anymore so it is left idle most of the time now.

Hi Fred, black smoke is an indication of unburnt diesel, something a Cummins shouldn't experience. The more common reason is injectors needing an overhaul. Qn: how many hours have the engines done?

The reason for asking about gearboxes is if they are Twindisc about which I have much knowledge.

 

[Fredd]

.Qn: how many hours have the engines done?

There's just under 1100 hours on them.

It appears that the engines have been looked after but it needs further investigation. The guy who showed it to me said that a big job was done on them a few years ago but he didn't know what exactly was done .
I have got a surveyor involved and he knows the company that does the servicing and he will contact them to get the history.
I like the boat so I hope that we can sort out any issues with the engines .
I have made an offer but it is conditional on the engines being ok and that any problems will be fixed before the sale is finalised.

 

[Piers]

It maybe that an injector service is sensible. Mine have 1600 on them and should be done soon, but I do not run them hard. WOT = 2600 yet I cruise at 1150. Hence the longer injector life.

If you have TwinDisc gearboxes, gear engagement should be smooth with nothing harsh. It's not a worry if it's harsh but they need adjustment (shims), which, depending on the build could be a 5 minute or 1 day job!

I'm a great Cummins fan. Strong, over engineered, long lasting engines. Good choice.