Fuel consumption Volvo TMD40

[scottie]

Both appear short of revs!

 

[Leighb]

Have you got an Eberspacher or similar fed from one tank?

Yes, but from the low consumption side, and in any case not in use this summer!!!

 

[Leighb]

Interesting one this.
Outwith all that’s been mentioned (my Favourite of which would be the injectors, but you say these are good) and usually no two engines are the same...is it at all possible that the props have at some point been miss matched or in different condition ?

Interesting point, last year I had a close encounter with the bottom and the Port prop was damaged and shaft slightly bent, this was sent away to be repaired, so it is possible that the Starboard prop is slightly out of pitch although it looks fine, something to check this winter. This could I suppose explain poor fuel consumption and failure to reach the same rpm as the Port engine.

 

[Leighb]

Both appear short of revs!

What max loaded rpm would you expect from a TMD40A? The workshop manual gives 2 speeds, "Governor overrun" speed as 3600, "Max unloaded" speed as between 3900 and 4080.

 

[Leighb]

forgot about the lack of intercooler - try measuring the compressed air temp at the turbo end. The inlet manifold is a big lump of metal bolted tight to the engine so will probably just get to engine temp and not vary much with load.
Was it a brand new turbo or a recon/rebuild ?
When you give the boat full throttle do both engines increase speed at the same rate or does one accelerate rpm faster than the other?

Turbo was new AFAIK, certainly an unpainted casting which looked brand new.
I have not tried just pushing the throttles to full in one go, I tend to increase speed more slowly, so have not seen if there is a lag between the two on acceleration.

 

[scottie]

What max loaded rpm would you expect from a TMD40A? The workshop manual gives 2 speeds, "Governor overrun" speed as 3600, "Max unloaded" speed as between 3900 and 4080.

Sorry!
From memory I thought 3800 wot underload but if book says 3600 then that would be correct

 

[QBhoy]

In response to my earlier post about propellers..perhaps worth checking sending the props away for balancing and pitch check. Often when repairing a damaged prop, there may be a chance of the pitch fluctuating. Ideally it shouldn’t and should be checked a worked to tolerance...but it’s often not an ideal world. It threw me a while ago when baffled over a negative prop slip result. Turns out my presumed 19” prop had been reworked to a 21” and with cup. Lesson learned, haha.

 

[boatmike]

A further thought. Do you have turbo boost gauges fitted? If so are they giving the same readings? When I first rebuilt my TMD41A it was down on boost due to a slight leak on the air pipe from the turbo to the manifold. Easily miss fitted on the Volvos if you are not careful. Worth checking even if you have no boost gauges as they are pretty easy to remove and refit. If there is a leak the suspect engine would be down on revs and use more fuel. The higher working temperature is a concern though and should not really be caused by such issues. Have you checked the thermostats? Its easy to do if you stick them in a saucepan of water with a thermometer and bring them up to temperature..... When checking that everything is clear don't forget to check the oil coolers too. You can check the gauges are reading correctly by swapping the leads over at the back of the gauge panel and seeing if the readings show the same. How hot are they? What are the actual temperatures of each?