Black sludge in "C" intake ?

[KEVIN MUNCASTER]

The intake manifold on my 86 C10 is lined with black sludge. As I am eliminating my non-functional EGR valve, should I remove the intake and remove the sludge ? Why is it there ? Is this normal ? Would I be better, if removing the intake anyway, to look for a "J" intake ?

I realize that the inside of these engines is prone to be "Diesel Black", but just wondering if this is ok.

Kev :confused:

[Subzilla]

It is normal. The black stuff accumulates because of the oil vapors circulating through via the CDR (not very technical answer, someone else elaborate!). My 6.2's have always had it. You could clean it but I would definitely look for a "j" intake for better breathing ability. I've got one sitting on the garage floor waiting for installation onto the Blazer.

[john8662]

Yep, its normal, some intakes will be blacker than others. The best method would be to acquire a J series intake, preferably the dual plane one, because its a direct bolt up to your engine. The later single plane intakes will work but you will have to change your valve cover for the newer CDR setup. I installed a J intake on my 86 6.2 truck, never regretted it, not really any more power, just runs cleaner.

I think the intakes get gunked up by the CDR valve moving blow-by gasses into the intake (normal) and the dirty black exhaust sticking to the oil mist from the CDR. Just an accumulation of oil and diesel sut.

If you decide to keep the C intake, just take it to a machine shop and have it vatted and cleaned out completly, couldn't hurt, then find a freeze plug and drive in the hole where the CDR valve set, this will make less air restriction in the intake (no valve to block airflow).

[KEVIN MUNCASTER]

I couldn't find a freeze plug locally that will fit tight. A 47 mm is too big and 45 is too loose. I could use the 45 with some copper silicone, but not sure if it will stay in place. I'll get my jobber to order a 46mm and see if it fits better. Thanks for the feedback fellas. This site has been a great help.

Kev tongue.gif

[DmaxMaverick]

About the freeze plug in the EGR....

I've done a couple that I just could not fit with a freeze plug. No matter what I did, the freeze plug just would not work. You could try a motorcycle engine ridge reamer/bore cutter to enlarge it

Another solution, although it will cost a little more, is have a blank-off plate made. Take the intake to a machine/welding shop (or do it yourself if you can) and have them make a plate that will use the original bolt holes to mount it. Apply some sealer and bolt it down. If a "J" or HMMWV intake isn't in your future, this will work well and is easy to do.

Cleaning the intake....
The best/easiest method is to soak it in Diesel fuel. You won't find any degreaser that will cut that stuff worth beans, and the hot tanks don't do a good job, and the chemical baths are not good on the aluminum. If you have access to a steam cleaner (a REAL steam cleaner, not just a pressure washer), it will help to get the thick stuff off before the Diesel wash.

[KEVIN MUNCASTER]

Hey - why didn't I think of that. I'll use the EGR as a template and cut a piece of plate to the same dimensions, drill 2 holes and, voila ! Problem solved....forget the frost plug idea.

Thx, I knew I kept you guys around for a reason...lol

Kev :D