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Signs of fuel or oil on water at boat exhaust

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delacova

New member
I have a 1989 38 Hatteras Sports Fisher with In-Line 6-71's. I just had the Starboard Block Heater replaced and subsequently have noticed that after starting the engines, while warming up at the dock, there is a sign of fuel or oil on the water around the boat exhaust on the Stbd side. I have not had this problem before. Can anyone please advise what may be causing this and what I can do about it? Could it be attributed to tha changing of the block heater?

Thank you
Rene
 
I seriously doubt that the block heater replacement had anything to do with it unless, of course, the new one isn't working properly and the stbd engine is colder than the port at start up. Any smoke associated with your observation?
 
I had the same problem on a 8.2t 4 cycle.
The causes were:
1) sea water pump blockage that provoked an insufficient sea water circulation along with heat exchangers obstruction
2) engine temperature out of control generating...
3) head gasket multiple burns and exhaust/cooling fluid mixing
 
Thank you for your response. No, no signs of smoke other than the ususal white smoke at starting a cold engine that dissipates quickly.
 
I know this is an old post, but did you ever find a solution? I have an Egg Harbor Cruiser with the same issue and believe it to be a clogged fuel injector, but not sure if there is a way to pinpoint the faulty injector without pulling them all. They have less than 100 hours on them since new. Again the fuel is in the water of the exhaust and therefore a potential environmental issue. The fuel is not int the radiator water. Thank you.
 
I waited to see if delacova responded. You will note that he spoke of "white smoke" upon starting a cold engine. "White smoke", as most people call it, is raw, unburned, atomized fuel "cloud" and not smoke at all. This is usually indicative of a very worn engine, especially if engine block heaters are being utilized and given the fact that they are functioning properly.

The fuel doesn't ignite due to a lack of sufficient compression to create the heat in the cylinder required to burn the fuel. A fresh, properly operating, 2 cycle Detroit Diesel does not typically emit "white smoke" on start up in temperate climates and even in cold climate the starts are "white smoke" free when engine block heaters are used.

"White smoke" is obviously where his "fuel sheen" on the water was originating and I really don't remember if I did or did not try to respond to him at the time. I probably meant to but didn't for some reason.

At any rate, it is clear to me that his engines were, most likely, worn to the point of having fairly low compression when cold and were probably experiencing some excessive cranking before friction in the cylinder would build enough heat to fire the fuel. Not much to be done but to "kit" the cylinders to alleviate that problem although the block heaters are always a good first try.
 
jgmo said:
I waited to see if delacova responded. You will note that he spoke of "white smoke" upon starting a cold engine. "White smoke", as most people call it, is raw, unburned, atomized fuel "cloud" and not smoke at all. This is usually indicative of a very worn engine, especially if engine block heaters are being utilized and given the fact that they are functioning properly.

The fuel doesn't ignite due to a lack of sufficient compression to create the heat in the cylinder required to burn the fuel. A fresh, properly operating, 2 cycle Detroit Diesel does not typically emit "white smoke" on start up in temperate climates and even in cold climate the starts are "white smoke" free when engine block heaters are used.

"White smoke" is obviously where his "fuel sheen" on the water was originating and I really don't remember if I did or did not try to respond to him at the time. I probably meant to but didn't for some reason.

At any rate, it is clear to me that his engines were, most likely, worn to the point of having fairly low compression when cold and were probably experiencing some excessive cranking before friction in the cylinder would build enough heat to fire the fuel. Not much to be done but to "kit" the cylinders to alleviate that problem although the block heaters are always a good first try.
Click to expand...


Thanks for your quick reply. The smoke seems to clear up once the engine warms up, but there is still a significant diesel fuel sheen in the water. I noticed the white cloud and sheen after I replaced the fuel filters and have subsequently replaced them again with no change. Both 8v53s are in good shape. I did replace a cylinder and piston several years ago due to a hydro lock...bent rod...but replaced everything with new parts and the engine ran perfect for over a year...but not many hours.

I am hoping it is an injector issue, but it may be related to the new cylinder and piston. I sure hope not. My next action unless you have a better idea is to remove the injectors and have them cleaned. I guess i should have a compression check before I spend that money though. I have heard you can tell the faulty injector or cylinder by using an IR thermometer to see which exhaust is cooer than the rest. Im not really sure that will work with a marine engine with the water cooling though. Any thoughts and or suggestions are appreciated.
 
While it is possible that you have a "dribbling" injector causing this, I agree with you that you should first verify that you have compression that is conducive to cold start. I'm not a 53 mechanic so I don't have any specifications to give you. Minimum for a 71 series is 425 psi. and I would think that the 53 would come in around that if not a little lower. These things will run fairly well with compression as low as 350psi or so but they don't start well when cold when they are that worn.

Your IR thermometer idea is useful with on highway and off road engines but, as you say, might not work with the water cooled exhaust. I've never tried it. They do make a "heat crayon" that you can rub on metal adjacent to the exhaust port and will change color at a given temperature that might yield some useful information. I would certainly try that if you can find some.

Don't forget the exhaust valves when considering the compression equation. Having them properly adjusted and fully seating is equally important to cylinder sealing as are the pistons and rings.

Hope some of this helps, and good luck.
 
Jgmo,

Thanks for the exhaust valve and temp color crayon suggestions. I'll let you know what I find. Once I move the couch and the rest of the living room furniture I can remove the carpet and the floor to get to work. Too much fun. :(. Thanks again for you time and excellent comments. Cheers.
 
Hi

I do not know much about all of this but i had the exact same issue and it turned out to be a bad fuel injector, once repaired it went away...just in case that helps :)
 
rszarka said:
Hi

I do not know much about all of this but i had the exact same issue and it turned out to be a bad fuel injector, once repaired it went away...just in case that helps :)
Click to expand...

Thanks, that sounds encouraging. We're you able to identify the bad injector or did you send them all to the shop for testing and cleaning?
 
cbaymac said:
Thanks, that sounds encouraging. We're you able to identify the bad injector or did you send them all to the shop for testing and cleaning?
Click to expand...


The mechanic came out to the boat took off the rocker covers and revved the engine listening to each cylinder from that he was able to ascertain which injector was not working properly. Have no idea how he knew, something to do with the sound and the knocking. He took out the bad injector came back the next day put it back in and it was all fixed. Apparently the tip was shot and it was
not atomizing the fuel but just dripping it into the cylinder so there was un burnt fuel in the exhaust.
Another symptom I had at the same time was lots of black smoke ESP at anything over idle speed which also went away. Black smoke and a light film of fuel on the water at idle were the symptoms.

My advice use a very experienced Detroit diesel mechanic and it
will
cost you much less in the end!! Because he could tell which injector was bad by just listening we did not have to pull all of the injectors !! Big savings there!! They guy had decades of experience working on marine detroits!! Like jgmo advised me in another thread using the right mechanic is everything!!
 
Your guy probably used a stethoscope, screwdriver or piece of pipe held to his ear and to the exhaust port. I know that with my hearing, I probably couldn't pull that one off. I used the heat crayons and they were effective for me.
 
I'm going to give it a go next week. Will try the heat crayon if I can find one and the IR thermometer as well as a make shift stethescope. Photos and YouTube videos to follow. Thanks.
 
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