Moody 46 - slow under steam with Volvo TDM22

[destiny]

In idle, revs up to 4000 no problem, in gear engine turns 2300 max giving 6 knots - she should make 9 knots max and cruise at 7.5/8 (78hp). Boat has clean bottom and I've just serviced engine (clean exhaust - no muck from centrifuge pre-filters, clean tanks - biocided). Gearbox does get hot, but nothing unusual. This enigine's been hardly used (500 hrs) and runs very sweetly - I just bought boat and am very confused! Any ideas much appreciated!

 

[savageseadog]

Is the prop the right size

 

[Spacewaist]

Get someone to look at it. I am no mechanic, but it seems to me you have a power loss problem.

I had a TMD22 in a Hallberg Rassy 42. 2500 revs was the normal cruising revs. 2800-3200 when in a hurry higher in a panic. The manual invites you to cruise at 3200 revs (I recall that is about 80% of the max revs)

 

[KREW2]

Could the stern gland be too tight

 

[Stemar]

Does the engine smoke under load & if so, what colour is it?

 

[Norman_E]

My earlier post on this thread has vanished. One point I made has not been covered by others. Most Volvo gearboxes incorporate an overload clutch designed to slip if the prop is stalled. If the gearbox is hot it might be from heat generated by this clutch slipping a little due to excessive loading from a rope fouled prop, an overtight gland, propshaft mis-alignment or an oversized prop. Slip would have to be quite limited or the engine would start to race.

 

[Eightball]

hi you will fined that it is your prop ive just gone through same thing alls well now you have all the same problems i had . eazy ot fix take it to a prop doctor. he will put it right . hope this helpsyou regards dave.

 

[destiny]

Many thanks all.
No smoke from exhaust - I'll check on overload clutch.

 

[Norman_E]

One other point. If the engine revs to 4000 with no load, but will not do so under load it is possible that there is a problem with the turbo boost. If there is an air leak between turbo and engine this usually results in excessive smoke, unless sophisticated engine management reduces the fuelling, followed by turbo failure due to the turbo spinning too fast. If the engine management reduces the fuelling to cope with reduced boost pressure then the result is loss of power. If your engine has a rubber hose from the turbo to the inlet manifold check it carefully for splits, chafed or worn areas, or loose connections. I say carefully because on my turbo diesel car there was a split in the hose that only opened under pressure, but it still managed to destroy the turbo.