Sheen/Sooting from my 7.6BTD - troubleshooting advice?

[dtfeld]

Thats not good. Is it now constant output of soot of only start up/shutdown? Regardless its either unburned fuel or oil...

I would start by checking the cylinder compression as you can borrow a compression test kit from a local auto parts store and is pretty easy to do through the glow plug holes. It could be bad compression in one or more cylinders. There is a test procedure in the technical manual. But it could be it needs a head torquing and valve clearances adjusted, or stuck/bad piston rings.

Beyond that, we get into fuel metering from the injection pump. One thing to check is that you fuel run solenoid is pulling all the way back, but I would expect under fueling in that case...

 

[ttmott]

Thats not good. Is it now constant output of soot of only start up/shutdown? Regardless its either unburned fuel or oil...

I would start by checking the cylinder compression as you can borrow a compression test kit from a local auto parts store and is pretty easy to do through the glow plug holes. It could be bad compression in one or more cylinders. There is a test procedure in the technical manual. But it could be it needs a head torquing and valve clearances adjusted, or stuck/bad piston rings.

Beyond that, we get into fuel metering from the injection pump. One thing to check is that you fuel run solenoid is pulling all the way back, but I would expect under fueling in that case...

Don't forget also that over-fueling will show in an oil analysis.

 

[dtfeld]

My progression would be based on it being easy/something simple.

Check fuel shut off solenoid
Compression Test
Torque the head/Check valve clearance

Re evaluate.

Edit…see you did oil samples already.

 

[fwebster]

Another cause of sooting in smaller diesels is dirty injectors. Any diesel specialty shop that rebuilds injectors can pop test injectors.
i had that done at 1000 hours on my 8.0BTD Westerbeke. The process is to pump solvent thru the injectors to see when they open and to visualize tge spray pattern. In my case, the diesel shop saw a little carbon in one injector but the solvent pssing thru the injector during the test cleared the obstruction. The cost was $75 for the test, new sealing rings and UPS shipping both ways.

You should re-torque the hed bolts while you are at it…….

Frank

 

[GnrlPatton]

Thats not good. Is it now constant output of soot of only start up/shutdown? Regardless its either unburned fuel or oil...

I would start by checking the cylinder compression as you can borrow a compression test kit from a local auto parts store and is pretty easy to do through the glow plug holes. It could be bad compression in one or more cylinders. There is a test procedure in the technical manual. But it could be it needs a head torquing and valve clearances adjusted, or stuck/bad piston rings.

Beyond that, we get into fuel metering from the injection pump. One thing to check is that you fuel run solenoid is pulling all the way back, but I would expect under fueling in that case...

It was only under really heavy load (AC, Microwave and Water Heater all on - pulling about 20A on one leg and 10 on the other) that I saw the stream of darkness coming out the exhaust. When I shut down the Microwave and Water Heater (left the AC going), the water cleared up and that's when I sampled it for the second pic. As far as I could tell, it didn't happen on startup, though to be fair I was really only looking for water flow, not what it looked like.

I like your idea about the compression test, that seems like a fairly easy first step, along with the fuel solenoid shutoff. Having never done the head torque or valve clearance, I'm not sure if that's over my head or not, but I'll look for details on how to do it before calling in a mechanic.

Thanks David!

 

[GnrlPatton]

Another cause of sooting in smaller diesels is dirty injectors. Any diesel specialty shop that rebuilds injectors can pop test injectors.
i had that done at 1000 hours on my 8.0BTD Westerbeke. The process is to pump solvent thru the injectors to see when they open and to visualize tge spray pattern. In my case, the diesel shop saw a little carbon in one injector but the solvent pssing thru the injector during the test cleared the obstruction. The cost was $75 for the test, new sealing rings and UPS shipping both ways.

You should re-torque the hed bolts while you are at it…….

Frank

Thanks Frank. I did just have the injectors rebuilt and tested prior to this run, I think it was you earlier in the thread that suggested it so that was the next step in the progression. I've also replaced the exhaust elbow as someone else suggested, so I think we're probably onto compression or valves as the guys commented earlier.

 

[dtfeld]

It was only under really heavy load (AC, Microwave and Water Heater all on - pulling about 20A on one leg and 10 on the other) that I saw the stream of darkness coming out the exhaust. When I shut down the Microwave and Water Heater (left the AC going), the water cleared up and that's when I sampled it for the second pic. As far as I could tell, it didn't happen on startup, though to be fair I was really only looking for water flow, not what it looked like.

I like your idea about the compression test, that seems like a fairly easy first step, along with the fuel solenoid shutoff. Having never done the head torque or valve clearance, I'm not sure if that's over my head or not, but I'll look for details on how to do it before calling in a mechanic.

Thanks David!

One other easy thing I can think of…fuel. Are you using the fuel “cocktail”? Maybe you got a bad load last fill up. CAT SOS will also check fuel quality for $20.

Torquing the head is easy except for access. The specs and bolt order are in the service manual. All you need is a good torque wrench.

Setting the valve clearance is a little more involved as it requires access with a good viewing angle of the the crank pulley . You need to see the timing marks. Mine sits backwards so I almost need a camera on it to see them. Procedure is in the manual as well and fairly well detailed.

 

[GnrlPatton]

One other easy thing I can think of…fuel. Are you using the fuel “cocktail”? Maybe you got a bad load last fill up. CAT SOS will also check fuel quality for $20.

Religiously! I have multiple batches made up and kept onboard for anytime I do a fill up. Fuel never goes in the tank without the cocktail going in as well. However, I have not used the boat (or generator) much over the past year due to my wife's breast cancer treatments, so the fuel that is in the tanks is pretty old. There's only about 1/4 tank left now, and I will be going for a fill up soon, might be a great time for Franks' shock treatment and then Racor filters change...

I also didn't operate the generator much at all over that past year because I had intended to get the injector work done first, but that kept getting pushed back due to the other things happening in life. That's why I initially thought there was just buildup working its' way out when I did run it hard the other day.

 

[ttmott]

Religiously! I have multiple batches made up and kept onboard for anytime I do a fill up. Fuel never goes in the tank without the cocktail going in as well. However, I have not used the boat (or generator) much over the past year due to my wife's breast cancer treatments, so the fuel that is in the tanks is pretty old. There's only about 1/4 tank left now, and I will be going for a fill up soon, might be a great time for Franks' shock treatment and then Racor filters change...

I also didn't operate the generator much at all over that past year because I had intended to get the injector work done first, but that kept getting pushed back due to the other things happening in life. That's why I initially thought there was just buildup working its' way out when I did run it hard the other day.

Kevin - the generator appears to function normally at high loads right? Check the AC power frequency fully loaded to make sure it is really turning 1800 RPM (which is 60 hz). If for example the governor is holding the fuel rack full open because the RPM is less than 1800 then sooting and a sheen will be in the exhaust. A restricted exhaust system can be a contributor to all of this. The service manual does a great job on going through checks and adjustments on the injection pump and governor. If you don't have that service manual PM me your email and I'll send it to you.

 

[GnrlPatton]

Kevin - the generator appears to function normally at high loads right? Check the AC power frequency fully loaded to make sure it is really turning 1800 RPM (which is 60 hz). If for example the governor is holding the fuel rack full open because the RPM is less than 1800 then sooting and a sheen will be in the exhaust. A restricted exhaust system can be a contributor to all of this. The service manual does a great job on going through checks and adjustments on the injection pump and governor. If you don't have that service manual PM me your email and I'll send it to you.

It appears to be normal at high loads. The only time it bogged down was when I had AC, water heater, microwave and stovetop on at the same time, to run the test. I've admittedly never done all 4, but have had 3 of them on at the same time, on generator power, with no problems. I didn't look at RPMs then, but it sounded normal, maybe it was bogging a bit. The voltage on one leg was starting to drop under 100V, so I turned off the stovetop and it returned to normal. That's when I collected the water sample from the exhaust.

I think I have the service manual you mentioned, but if I don't, will PM you.
Thanks Tom.