engines different consumption

[robymayway]

Hi all,
my hat conv 37 year 1981 has two dd 325hp and run very regulary at 2100 rpm.
the only thing I don't understand is that right engine has a consumption of 35/40 % more than left engine.
Only one thing: the right side is a little bit more warmer ( at the minimun too)
not smoke, not difference rpm, not less of power....all perfect and goes regulary!!
I have not change blades or other. Last year the difference was around 5/10%. This year I have done all measurement in difference condition but the result is always the same.
Could you suggest me some possible reasons?
many thanks

 

[Boatsb]

Hi all,
my hat conv 37 year 1981 has two dd 325hp and run very regulary at 2100 rpm.
the only thing I don't understand is that right engine has a consumption of 35/40 % more than left engine.
Only one thing: the right side is a little bit more warmer ( at the minimun too)
not smoke, not difference rpm, not less of power....all perfect and goes regulary!!
I have not change blades or other. Last year the difference was around 5/10%. This year I have done all measurement in difference condition but the result is always the same.
Could you suggest me some possible reasons?
many thanks

Generator draws from where?


How are you measuring consumption?

 

[Avenger]

35-40% is a LOT. More than a generator would burn. Couple of possibilities; any chance you're returning fuel to the wrong tank? Higher engine temp may indicate that the engine is working harder than the other, and maybe it's the other engine that is weak. Can you measure turbo manifold pressure or exhaust temp?

 

[Boatsb]

35-40% is a LOT. More than a generator would burn. Couple of possibilities; any chance you're returning fuel to the wrong tank? Higher engine temp may indicate that the engine is working harder than the other, and maybe it's the other engine that is weak. Can you measure turbo manifold pressure or exhaust temp?

Depending on how many hours the genny runs. I use about 100 gal per year running mine

 

[jim rosenthal]

I'd suggest that you make certain that both of your marine gears are the same ratio. Don't laugh; this happened to one of our members, who finally determined that J&T had sold him two different ZF marine gears- one was a 1.5 ratio, the other was a 1.75 or 2.0. Amazing.

That is not the most likely explanation, though. Are both diesels returning to their respective tanks or to one tank?

 

[Avenger]

Depending on how many hours the genny runs. I use about 100 gal per year running mine

He says he runs at 2100 very regularly. From that, I'm assuming that he's actually using the boat when the genny is running. Not just running the A/C on the hook between annual trips to the fuel dock.

Also, I'm making assumptions in light of his observation about this season vs. last season. I @$$ume that he hasn't given up actual boating to become a dock queen since then.

Remote diagnosis sux.

 

[Finalee]

Warmer can mean working harder. I would suspect a bind in the drive line. Out of line , or bent prop , dirty running gear that side etc .

 

[Boatsb]

He says he runs at 2100 very regularly. From that, I'm assuming that he's actually using the boat when the genny is running. Not just running the A/C on the hook between annual trips to the fuel dock.

Also, I'm making assumptions in light of his observation about this season vs. last season. I @$$ume that he hasn't given up actual boating to become a dock queen since then.

Remote diagnosis sux.

Plus most of these hatts have genneys drawing off the port tank. Meanwhile my heaviest year of genny use had 67 days of the boat leaving the marina. I think that would be hard to qualify as a dock queen. And yes more than 1 trip to the fuel dock.

 

[robymayway]

Hi all,
my hat conv 37 year 1981 has two dd 325hp and run very regulary at 2100 rpm.
the only thing I don't understand is that right engine has a consumption of 35/40 % more than left engine.
Only one thing: the right side is a little bit more warmer ( at the minimun too)
not smoke, not difference rpm, not less of power....all perfect and goes regulary!!
I have not change blades or other. Last year the difference was around 5/10%. This year I have done all measurement in difference condition but the result is always the same.
Could you suggest me some possible reasons?
many thanks

thank you!!
I haven't use generator and measurement has been refilling both tank in the same time and after 4 hour of cruising, refilling once again....

 

[robymayway]

He says he runs at 2100 very regularly. From that, I'm assuming that he's actually using the boat when the genny is running. Not just running the A/C on the hook between annual trips to the fuel dock.

Also, I'm making assumptions in light of his observation about this season vs. last season. I @$$ume that he hasn't given up actual boating to become a dock queen since then.

Remote diagnosis sux.

Hi, many thanks,
genny is switch off, I have done regulary maintenance on july2013 but this problem began since june 2013.
I don't understand...

 

[robymayway]

I'd suggest that you make certain that both of your marine gears are the same ratio. Don't laugh; this happened to one of our members, who finally determined that J&T had sold him two different ZF marine gears- one was a 1.5 ratio, the other was a 1.75 or 2.0. Amazing.

That is not the most likely explanation, though. Are both diesels returning to their respective tanks or to one tank?

Hi many thanks!
Both marine gears are exactly the same ratio.
Problem began on june and maintanence and hull painting have been done on july. I give a check on return fuel but all seem to be correct.
Very strange!

 

[chris piazza]

I'm guessing you have damaged a prop, this causes the load to go up dramatically on one engine. I have seen it be 15-20% load difference between engines.

Chris
Superior Nights 53C

 

[Fanfare]

I had a leak in one fuel cooler which was putting raw fuel into the exhaust water. I could see the diesel sheen from just one engine. Have a look after startup, again at maybe 1000 rpm. It should show up if that is the problem.

 

[captddis]

The fuel select valves can leak internally and send fuel back into a tank that is supposed to be off.

 

[robymayway]

I had a leak in one fuel cooler which was putting raw fuel into the exhaust water. I could see the diesel sheen from just one engine. Have a look after startup, again at maybe 1000 rpm. It should show up if that is the problem.

Hi Fanfare!, I think your suggestion may be really interesting!!! It should be the right solution, in fact the water that flow out from the right engine exhaust, seems to be contaminated from diesel.
I noticed it when I start the engine and when I came back to my dock after cruising.
Also when I start engine after 1 week of stop, I noticed a white cloud into the water...

How can check it???

 

[robymayway]

I'm guessing you have damaged a prop, this causes the load to go up dramatically on one engine. I have seen it be 15-20% load difference between engines.

Chris
Superior Nights 53C

Hi Chris,
I was taking care your suggestion, but props have been check on june 2013 during hull maintenance and also there aren't vibrations during cruising.

I think that Fanfare reply may be a correct option....now I need to find out how can give a check to the fuel cooler...
I 'll let you know!

 

[Finalee]

Remove and pressure check. However this does not explain one engine warmer.

 

[nlblanchard]

Just to add a little more to the question here goes. Our 38 Hatt has always (at least for the 13 years we have owned her) used exactly the same fuel consumption on both engines. After a breakdown and 2 month stay in Annapolis trying to get a transmission replaced the starboard engine (replacement side) now appears to drawn apx 60% more fuel than port engine. The added puzzle is that our total fuel consumption has remained exactly as before with tank levels being the difference. Our feel is that the return fuel from both engines is all going into port tank but how and why now. All shut offs are in correct position. Really puzzled. Any thoughts? By the way, a hello to Jim Rosenthal who I met in passing while tied up along Ego Alley in Annapolis. Beautiful boat Jim.

 

[saltshaker]

Just to add a little more to the question here goes. Our 38 Hatt has always (at least for the 13 years we have owned her) used exactly the same fuel consumption on both engines. After a breakdown and 2 month stay in Annapolis trying to get a transmission replaced the starboard engine (replacement side) now appears to drawn apx 60% more fuel than port engine. The added puzzle is that our total fuel consumption has remained exactly as before with tank levels being the difference. Our feel is that the return fuel from both engines is all going into port tank but how and why now. All shut offs are in correct position. Really puzzled. Any thoughts? By the way, a hello to Jim Rosenthal who I met in passing while tied up along Ego Alley in Annapolis. Beautiful boat Jim.

See post #14

 

[robymayway]

Hi all, after all your suggestions, I find out the solution on my strange puzzle...
It was a mix of reasons:
the first
the return valve on right engine was in an incorrect position..Since I bought my boat, I never had touched this level before, but I suspected that in june changing the battery, probably, I moved it...
the second,
I've disassembled the return fuel cooler and checking the pressure and there was a little hole in the element.
Tomorrow I will go ahead with a a new cycling of acid phosporic to find out the warmer problem.

great thanks to all for your support!