Thorneycroft Diesel Marine Mechanic-ELY

[Delta3]

Hi there!!

Okay greetings over, down to the serous stuff!!

Does anyone know of a very good mechanic that can sort two CMD Thorneycroft engines out.

The boat lies near Ely on the Great Ouse, the port engine is only producing about a 1000 revs, and the starboard 1500, the boat is a displacment, with a designed hull speed of 9knots, at the moment with the combined engines we are only getting about 5kn, full throttle, the port side giving anywhere from 1 to 3kn and the starboard a max of 4.5.

There's already been two mechanics have a look at it, the fuel lines have been checked, the fuel filters have been checked, the air filters are clean, doesn't appear to be a problem with the injectors, the boat will achieve, 4000 revs in neutral, just dies off when under load, more so on the port engine.

The props are clean, not sure about the underside of her, but that would't explain the alarming poor performance.

I am hoping to take her round the North Norfolk coast and onto the Broads at Lowestoft, we did have a run out on the tidal section of the Great Ouse but with the tide with us we were only achieving 6 kn SOG.

 

[orizaba]

at full throttle are getting alot of black smoke from bothengines when under load?
have you had 9 knots out of her before?
if not what is the max you have had,in other words is this something that has changed recently

 

[Delta3]

Hi,

Only had the boat 12 weeks, no black smoke, the engines have only done 150 hrs each, albeit they are now 10 years old, it's been used as a live aboard, the starboard engine, which is the better of the two, produces a fair amount of steam and slightly less water than the port side, but that is the better runner of the two!!

 

[alb40]

Sure its not something simple like dirty / fouled props? Or that she's simply vastly overpropped, maybe with two different props?

 

[SimonA]

I have a BMC diesel which I thought had a fault as I could only get 2000 RPM in gear but 4000 RPM out of gear. Turned out I had a direct drive gearbox fitted which was why it had low revs. My hull speed is supposed ot be 12 knots with twin engines, I have a single engine and struggle to get 5 knots.

Sorry, don't know of any decent diesel mechanics on the Gt Ouse, but if you find one let me know!

 

[Cliveshep]

I don't know anyone on the Gt Ouse either, but I do go along with Cattleya & Alb40 in that checking props for serious over-propping or type of gearbox makes a lot of sense. You talk about steam - no head gasket faults? Temp ok?

Most Thorneycrofts are marinised car/van/truck lumps, would a commercial garage mechanic not be able to check the lumps out?

 

[D3B]

Not sure if he is any good on the Thorney's or if he is till about but there was a fella called Cliff that used to work out of the Fish & Duck before it was condemned. very knowledgeable person on engines.
if you called into the marina (still open afaik) someone might know if he is still about and have contact details. used to live in Kings Lynn ( i think)
I know he repaired a Gardner <sp> on an old Thames tug he had on the river.

 

[orizaba]

re the steam i would change the raw water impellors on both engines,tyey don't like sitting in one place,
assuming your propellers,gearboxs stuffing box etc are the same,both engines should be roughly equal.as they appear not to be its possible that the compression is low on one engine,at 150 hrs if that is true they are hardly run in,they may just need a good workout to clear themseves out,
normally you would get black smoke if they were overpropped,i did and its pretty obvious under load,look for black oily marks nr the exaust outlets,
a mucky bottom would normally give you the same.
just because the design speed is 9 it does not mean you will get that.it might be worth speaking to these guys

lycos.co.uk bmc marine don't seem to be able to copy and paste them

 

[Bilgediver]

No black smoke.........You get 4000 RPM under no load so looks like the throttle linkages to the fuel pumps are ok...However you indicate the engines don t take load. Is it possible the fuel pump racks are a wee bit gummed up from not running.

Is the fuel pump an exterior mounted unit and accessible or is it mounted within the engine. If external it could be worth taking one to a fuel pump specialist.

By the way you dismiss a dirty hull however a fouled hull will easily account for loss of speed but usually the engines make a bit of smoke.

 

[Delta3]

[ QUOTE ]
Not sure if he is any good on the Thorney's or if he is till about but there was a fella called Cliff that used to work out of the Fish & Duck before it was condemned. very knowledgeable person on engines.
if you called into the marina (still open afaik) someone might know if he is still about and have contact details. used to live in Kings Lynn ( i think)
I know he repaired a Gardner <sp> on an old Thames tug he had on the river.

[/ QUOTE ]

Yeah, got Cliff's number in my boat numbers, problem is, you hear so many different stories on different people, the guy at the F& D was slagging him off, saying he was crap.

I actually met him at the Cutters Inn about a month ago, he introduced himself, I didn't know him from Adam, he'd had one over the eight, so I didn't get that much sense out of him, told me there was a bit of bad blood between the guy at the F&D and himself.

I guess it's attempting to get the engines running at their optimum and then seeing what speed she will produce, if she doesn't match her optimum hull speed, then it will be then time to start looking at the size of props, whether there is enough power with 2no 2 litre, 45 hp lumps at the heart of things, or whether the hull is fouled and slowing her down.

Just spoke to Cliff, he suggested that the steam could be by lack of compression, caused by a blown head gasket, but that's coming from the starboard engine, the one that is producing the better performance.


Ever feel you are going around in ever diminishing circles??

 

[D3B]

PM sent
Doug