3208, difference in fuel consumption

[Pietro]

I promised Darrel "docofthebay" to check fuel consuption of my 3208s at low rpm.
We finally had some good weather and fair sea last week end, so I was determined...but... I had a problem!

At 2500 rpm starboard engine was using some 15% more fuel than the port one and I was doing only 23 kts (instead of 25-26) with a perfectly clean bottom!

Then I tried full steam, the port engine reached 2800 and the starboard only 2700!!! The only viseable difference was some more smoke as the boat got into plane... smoke normal once on plane, i.e. very, very little!

So, this afternoon I have Caterpillar aboard... any idea before I face the mechanic??? :huh:

 

[melida]

Pietro,
I don't think it is prop related, since you said bottom is extremely clean and untill today you were happy with your current props.
It sounds like you are having either fuel or air restriction problem.
What about the fuel quality in starboard tank? Also the primary and secondary fuel filters and injectors, injection pump?
On the other hand how many hours passed from changing the air filter? Or leaking turbo? maybe the pipe/hose from turbo to aftercooler is cracked and leaking air? Or your aftercooler is dirty/clogged and can't supply cold air to the injectors.
Also you should check (and compare with port)the turbo boost pressure and vanes of the turbo.
These are the main causes of what you are experiencing unless any other past problem engine had.
Hope cat mech finds the problem.

 

[Pietro]

Pietro,
I don't think it is prop related, since you said bottom is extremely clean and untill today you were happy with your current props.
It sounds like you are having either fuel or air restriction problem.
What about the fuel quality in starboard tank? Also the primary and secondary fuel filters and injectors, injection pump?
On the other hand how many hours passed from changing the air filter? Or leaking turbo? maybe the pipe/hose from turbo to aftercooler is cracked and leaking air? Or your aftercooler is dirty/clogged and can't supply cold air to the injectors.
Also you should check (and compare with port)the turbo boost pressure and vanes of the turbo.
These are the main causes of what you are experiencing unless any other past problem engine had.
Hope cat mech finds the problem.

Yes, props are ok. Same fuel in tanks and new everything some 10 hours ago... may be a loss in turbo pressure, .. Sea trial with CAT service in a couple of hours!

 

[Pietro]

So, it seems somebody forgot to change the air filters. :smt021 They were really filthy. Now engine(s) go much better and starboard reached 2800. Consumption is still a little higher though. Tomorow we will clean the heat-exchangers and fix a leak in the fresh water circuit...

 

[docofthebay]

Thanks for trying! Hopefully you can get back out later and get some of those low PRM numbers. That would really help to know fuel use at the trawler speeds
I posted a thead earlier today about my weekend and how my boat bottom is fithy. Took me from 23 MPH at 2300 rpms to 18.5 MPH at 2300. Had some slight vibration too. Just spoke to a diver who will take my props into a shop for me and clean the bottom next week. Thanks for the tip on the air filters. I didn't change mine this year. The indicator doesn't show any restriction but it couldnt hurt to put new ones in.

 

[cod]

Very well could be props. Unless props were recently scanned to a class "S" accuracy. I had one engine burning more fuel and showed more load on engine. Everything checked out ok with engines, no vibration from props. Mechanic suggested having props reconditioned. Sure enough, after reconditioning engine fuel consumption and load were identical.

 

[melida]

So, it seems somebody forgot to change the air filters. :smt021 They were really filthy. Now engine(s) go much better and starboard reached 2800. Consumption is still a little higher though. Tomorow we will clean the heat-exchangers and fix a leak in the fresh water circuit...

Glad it's a 20-30€(part) fix and hope no other failures will happen.
You are in Med and each season or once a two season heat exchangers and oil coolers should cleaned.