a lot of smoke and soot ?

[craigrep]

My Dad just gave me his 88 Chevy c2500 with 6.2... this is my first diesel truck. The truck has 74k original, once he retired he stopped drive it all the time. My question is this truck blows black smoke something bad. Not at idle rmps, but once your foot is on the pedal it starts. And I don't mean floored, just maintaining speed its blowing black. I replaced the air filter today, when he gave it to me, he said he had not replaced in a while. When changing the filter I noticed the air inlet into the manifold (not sure what the part under the air cleaner is called) is loaded with black soot. Is this normal? How do I clean it? Should I clean it? Is there a fuel additive I should add? My Dad said someone told him maybe it needs injectors thats why its blowing that much soot. If you guys could please advise, that would be great. Thanks in advance. Craig

[john8662]

EGR.

Could be a problem with the valve or the solenoid on the bank of noids on above the valve cover.

For testing (or perm fix). For testing, remove the vacuum line from the solenoid outside of the air cleaner, drive it. For fixing, cut the vacuum line that comes out of the air cleaner, cut it approximatly 3" or so near the solenoid where it connects (outside of intake, above valve cover). Then take the correct size screw (usually 1/4-20) and put some silicone on the threads, screw it on both sides of the newly cut hose.

This will prevent a vacuum leak, and keep the solenoid from being able to open the EGR valve in the intake.

J

[DmaxMaverick]

........if it has EGR. It depends on the engine series. 8th digit of the VIN will tell. C = light duty, and EGR, J = heavy duty, no EGR. Otherwise, the "soot" will be oil vapor film caused by the CDR (Crankcase Depression Regulator, AKA: PCV), and does accumulate significantly over the years/miles. In any case, it's normal. Messy, but normal. A failed-open EGR will cause white smoke and reduced power.

The black exhaust smoke could be a couple things. If the new air cleaner doesn't help, it's likely an injection pump problem (barring another intake restriction). Worn out injectors, with the miles/time you have, would likely be white smoke, and rough idle and/or running.

A fuel additive is always a good idea, especially lately with the ULSD fuel. Name brand additives labeled for increased lubrication are good. Some offer increased cetane, which offsets poor fuel quality. Stanadyne, FPPF, Power Service (Diesel Kleen), Howes, etc. are all good, and most help with water contamination. If you have issues with ambient temps below freezing, an additive for that is recommended. Read the labels.

[Edahall]

The intake manifold on my 82 Suburban was coaked up as well and produced lots of black smoke when under power. I removed the intake manifold, blasted out all the crud with a pressure washer, cut out the EGR guts and smoothed out the casting. The difference afterwards was no black smoke and a lot more power. I ended up turning the pump to get even more power.

[craigrep]

Thanks for the info. I was thinking of using a soot snake (flexable attachment for shop vac ) and vacume out as much soot from the manifold as I can get and replace or bypass the EGR and see what gives.

Edahall - the soot you power washed out, was it soft soot or hard chunks? Mine is just soft soot as far as I can tell, so thats why I figured I could vacume it out.

Thanks again for the info I will post the results.

[DmaxMaverick]

Great care should be taken when cleaning. It is best to remove the manifold and soak it. Good ol' #2 works really well. The "soot" in the intake is moderately abrasive, but if a larger chunk gets into a cylinder, it could break a piston, rod, or valve, among other possibilities.

[craigrep]

Is it difficult to remove? Do I need to buy any new gaskets or anything to put it back on? Torque specs? Or am I over thinking this?

[Edahall]

Is it difficult to remove? Do I need to buy any new gaskets or anything to put it back on? Torque specs? Or am I over thinking this?

Mine had both the hard cruddy stuff as well as the soft soot. You need to remove the intake manifold to do a good job at cleaning it.

The intake manifold is not hard to remove. I had to remove mine several months ago for another reason and it took me about 1/2 hr for removal. Reinstallation took a little longer due to having to reinstall those injector rubber supports. I reused the old gasket. I torqued it down by feel.

[craigrep]

OK I'm good with that. I'll post the results and maybe some pics for laughs.

[craigrep]

Edahall - another question. Have you only had to do this once or is it a repeat problem? Do you think it is a bad EGR that caused this in the first place?

[Edahall]

I've only had to do this once. The intake manifold now stays completely clean after I deleted the the EGR.

[craigrep]

Thank you for the replys. Intake cleaned and EGR bypassed. Hugh difference in amount of smoke. It even runs better... better responce and seem to idle smoother. Thanks again for the input. Craig