Doesn't Look Good... Black Oily Substance between Manifold and Turbo

Highway Yacht · September 06, 2011, 02:17:23 PM

I just noticed a black oily film seeping from the pipe that goes from the exhaust manifold up to the turbo on the drivers side. I'm not sure if it is oil or unburnt diesel fuel or where it could be coming from. It has the color of black oil but feels thin more like the consistency of diesel fuel. The bus still starts on first turnover and no smoke on start up or idle but does smoke some if on the throttle. I just accepted that throttle smoke as coming from the large injectors and turbo. Engine is a 8V71T with what I was told was N90 injectors but I haven't verified that. There is no oily film inside the exhaust pipe at the muffler...only a film of dry black soot. Bus has not been driven on the road for several months but is cranked and driven around the farm monthly. I can't reach highway speeds here but have room to get up to 30MPH with no problem. Anyone have any ideas of what this black oily film is and what could be causing it??

luvrbus · September 06, 2011, 02:54:55 PM

To much idle time Jimmy it will clear up after a couple of hours of running at regular operating temps,you probably have N75 injectors N90 are a little heavy on the fuel

Len Silva · September 06, 2011, 02:57:40 PM

You are worrying about nothing. Until you can get up and run a couple of hundred miles at speed, none of those symptoms mean anything.

Highway Yacht · September 06, 2011, 03:16:04 PM

Thanks Clifford and Len... You sure know how to make a guy feel better..

Jimmy

bevans6 · September 06, 2011, 03:45:48 PM

If I remember the pictures right you have a ex-military tank engine, or similar, so it may be lower compression than a normal 8V71T. With 90's you are going to get that unburnt fuel maybe even worse than with smaller injectors and higher compression.

Highway Yacht · September 06, 2011, 04:03:14 PM

Quote from: bevans6 on September 06, 2011, 03:45:48 PM
If I remember the pictures right you have a ex-military tank engine, or similar, so it may be lower compression than a normal 8V71T. With 90's you are going to get that unburnt fuel maybe even worse than with smaller injectors and higher compression.

Yes Brian.. You are correct.. My 8V71T was a Military Surplus Tank Engine.. It has been in my bus since 2001..

Jimmy

Jriddle · September 06, 2011, 06:39:08 PM

Muffler will be full also. Don't ask me how I know but couple hours of driving with out to much traffic would be wise. I had same issue and found oil was very thin due to being diluted with fuel. I don't run mine much unless heading out for a trip now. The neighbor's got to see my big cloud of smoke.

John

bevans6 · September 07, 2011, 04:57:56 AM

Jimmy, it is the kissing cousin to mine, then, I believe mine may have been a military variant if it wasn't a straight industrial pump engine. Mine has N80 injectors, though. Is yours aftercooled? If it is, there is a coolant hose going down to the top of the block just to the right of the fuel pump. There is a hole in the block there on some engines for the coolant fitting to the aftercooler. Mine had a block preheater there which sprayed diesel fuel into the airbox and ignited it with a spark plug.

Brian

Highway Yacht · September 08, 2011, 04:09:45 AM

Quote from: bevans6 on September 07, 2011, 04:57:56 AM
Jimmy, it is the kissing cousin to mine, then, I believe mine may have been a military variant if it wasn't a straight industrial pump engine. Mine has N80 injectors, though. Is yours aftercooled? If it is, there is a coolant hose going down to the top of the block just to the right of the fuel pump. There is a hole in the block there on some engines for the coolant fitting to the aftercooler. Mine had a block preheater there which sprayed diesel fuel into the airbox and ignited it with a spark plug.

Brian

Brian... Not sure if it is aftercooled or not.. Can you post a post a picture of your engine of exactly where the coolant hose should be and I will check it against my engine and let you know..

Jimmy

bevans6 · September 08, 2011, 04:34:29 AM

Mine is not aftercooled, so I can't take a picture... Oh well. If you look at the engine from the front, you can see the fuel pump bolted to the front of the blower. It's about 2" to the right of the blower and down on the top face of the block. You would have a coolant tube about 1" in diameter there running over to the thermostat housing. If you don't have a coolant tube, it isn't aftercooled.

Brian

Highway Yacht · September 08, 2011, 12:36:44 PM

I guess it isn't aftercooled.. I don't see a coolant tube running anywhere near the front top of the block..

Jimmy

Highway Yacht · September 08, 2011, 01:00:28 PM

Brian... I think that spec sheet you posted might be the spec sheet for my engine.. If you look at the top of that Spec Sheet under General Data... The model listed there is 7083-7491. I had someone check my serial number awhile back and it cames back as being delivered on 8/06/1987, but under the serial number I also have the numbers 7083-7395 stamped too which I am guessing is a military spec model number and almost the same model number on your sheet.. I'm not sure if the Spec Sheet means model 7083 through 7491 or if 7083-7491 is a single specific model number. I did notice the date on the spec sheet is 1999 and my engine is a 1987 model. Do you happen to have access to other spec sheets that might have the model 7083-7395 on it by chance?

Jimmy

bevans6 · September 08, 2011, 01:30:35 PM

That's the only spec sheet I have and I have no idea where I got it! the 7083 part is what kind of engine it is, per this:

7 - V series
08 - 8 cylinder
3 - i don't know what this number means, if it was a 7, as in 7087, it would be a vehicle engine

The second half of the number is the model type information. My engine is 7083 - 7395, yours is 7083 - 7395 as well.
7 - means it's right hand rotation, starter motor on the left and oil cooler on the right, looking from the flywheel end of the engine.
3 - plain turbocharged engine.
95 - specific model number.

so we have the same engine, basically. I noted from pictures you posted earlier that yours is still quite in the configuration that it came in as far as the front engine mounts and fuel filter locations not being modified to MCI spec. I changed all that out so that mine is stock MCI as far as the mounts, cradle, and everything else is concerned. As noted earlier too, mine has N80 injectors. So the spec sheet isn't for your engine, but it's interesting none the less. Turbo-aftercooled and the big injectors equals 455 hp, and a no load speed setting of 2500 rpm - quite the rocket engine that one would be!

fun stuff: http://cgi.ebay.com/ebaymotors/8V71T-DETROIT-DIESEL-ENGINE-MILITARY-NEW-7083-7395-/220761754932

and http://www.jobbersinc.com/detroitd.htm has several. Mine looked exactly like these when I got it, except the starter motor was missing.

Brian

Just Dallas · September 08, 2011, 01:42:16 PM

Maybe this will help you.

Application Designations

7082 - 7200 Marine
7083 - 7200 Industrial F to F
7084 - 7200 Power Base
7085 - 7200 Generator
7087 - 7000 Vehicle F to F
7088 - 7000 Vehicle F to F

Design Variations

7082 - 7000 V71 "N" Engine
7082 - 7100 2 Valve Head Engine
7082 - 7200 4 Valve Head Engine
7082 - 7300 Turbocharged Engine
7082 - 7400 Turbocharged Aftercooled
7082 - 7500 Customer Spec. Engine

Design Variations

7087 - 7600 Constant H.P. Economy (TAE)
(California Certified)
7087 - 7700 Constant Horsepower (TT)
7087 - 7800 Constant Horsepower (TTA)
(California Certified)
7087 - 7900 Constant H.P. Economy (TTAE)
(California Certified)

Don Fairchild · September 08, 2011, 01:42:49 PM

Brian and Jimmy the numbers code out like this 7083-7395 the first 7 stands for v series in this case 71 series 08 is for 8 cylinders 3 is for industrial second 7 basic engine arrangement and rotation 3 is design variation in this case turbocharged 95 is specific serial number.

Hope that helps.

Don