Carbon clean out on top end, ideas?

[libtec]

How do you get the carbon cleaned out of a diesel motor top end without taking it apart? What kind of additives exist that are REALLY powerful.

I'm dealing with a Suburban 6.2 that when I bought it had 3 cylinders that were below 100 psi. After an hour of coaxing we got the motor to start on the good five and had a resulting misfire for the first 15 seconds. We nailed the pedal hard a half dozen times and one by one the cylinders came back up and we were pleased to have a rather smooth running engine. The motor had a loud, constant knock since we got it going three months ago. Monday morning when I started it up the knock was gone, simply vanished and hasn't even hinted at coming back. In that three months there has been times where I go out and start the truck and it just runs a little smoother and idles better than the day before, most noticeable is the smoother idle. This isn't a gradual change, it's happened in "steps".

I'm not an expert but it appears I might be fighting a carbon problem. The motor isn't much past 120Kish miles without any abuse, I'm just wondering how much potential I'm loosing if things are gummed up inside. Any advice would be appreciated. Thanks!

John

[john8662]

I doubt carbon deposits were your problems. Sounds to me that the engine was set-up for quite some time and the rings were stuck and you running the engine is breaking it back in. Another reason for your missing is probably from stuck injectors, running several tanks of fuel and some diesel fuel treatment should help to clean the injectors. The knocking sound can also be from a sticking injector as well.

How did you check the compression? What were the other cylinders compression (the 5 good ones)?

How long as this rig sat before you started running it?

[NH2112]

The best way to remove carbon, or so I've been told, is to mist water from a spray bottle into the intake with the engine at around 1200rpm or so. The water turns to steam in the cylinder and loosens up carbon deposits.

[libtec]

The rig sat long enough to have a spruce sapling grow up through the grill and about two feet over the hood.
compression test was with a snap-on tester, roughly 380 to 250 psi on the five good ones, below 100 on the bad three. the three bumped up to around 320ish after we started and test ran the rig. All 8 have improved, forgot the numbers from the last test, no up to date nuimbers however.
Water mist in the intake? Is this a good idea? Sounds risky, but if acceptable I'll give it a shot.
Thanks for the input guys!

John.

[MTTwister]

libtec - search on mist injection - Heath as an add-on system out that can be used in lieu of an intercooler. Water mist is an acceptable option for gaining power, and therefore shouldn't harm the engine.

Many years ago my Dad had Chevy that started a terrible knock. We took it into the local dealer (Dad was visiting from out of town). Normally they take the car out back and do this, but the service manager walked over, put his foot into it, took the rev's up to God knows what, and evidently blasted a big chunk of carbon to smitherines. Idled / ran fine after that.

Could be what you ran into.

[Jgreemo]

Do any of you guys have any experience with the Heath Water Injection system? They are selling the kit, minus tank, for $249. Also claiming a boost of 35-40 hp.

Thanks,
Jon