What's High Miles/Carbon

[FEF]

I've seen about a dozen 6.2s in Burbs and trucks. Many were clearly not running well at all. However, I ran into something that has me reconsidering what I thought I wanted.

I've found a '88 Burb, with 335,000 on the OD. The rig is Canadian, the gauges are metric. KPH, mPi, C for the temp, ect. That's a bit over 200k miles.

This is the best looking one I've seen. The engine bay is clean, and even has the stock bottle jack. I saw it fire up cold. There was slight (the least I've seen of all the engines) puffing coming out of the dipstick (when pulled out), no pressure felt from the oil fill tube, and no noticable oil vapors coming from the EGR (I think it's the EGR), into the intake. All the others has a steady stream of oil fumes going into the intake.

It ran well. Very well, indeed. The only sign it was an older engine was the thick layer of carbon goo on the walls of the intake.

The questions are:
- I understand these engines have seen 400k miles. This one sounds like a keeper to me. Have I noted any red flags?
- I know how to get carbon from the chamber, but I've got no idea how to clean the intake walls, other then with a rag and wires, and a shopvac. Anyone have any clever ways to ge the inside of the intake clean?

Sure, I understand buying anything used has risks, but this one, other then higher miles, appears to be pretty OK. It looks like a VERY good doner for my Revcon diesel swap.

Any thoughts?

[DmaxMaverick]

That "carbon" you found isn't carbon. It's the condensed oil vapor that you "didn't" see coming from the CDR (Crankcase Depression Regulator). Under normal conditions, there should be a slight fog of oil and water vapor coming out of it. Intake vacuum (as slight as it is) will help pull it through. If it has EGR (that pod in the middle of the intake, if it has one), it will make the oil grime build up worse, as the exhaust gases bind with the vapor and stick to the inside of the intake plenum. In any case, as bad as all that looks, it's absolutely normal and no reason to jump back. To clean it, you will have to remove it. You do not want those chunks falling through the runners and into the valves/cylinders. The best solvent I've found to cut that stuff is good ol' #2. Soak it a while and hit it with a wire brush. You could knock it out with a die grinder with a wire wheel, but it will leave chunks in the no-see-ums (and makes a big mess).