I agree with others, the white is probably ash on the somewhat hotter valve head surfaces. The ash probably came from the oil in the intake, hence the even and consistent deposits on both valves in all cylinders. I'm a little non-plussed that the intakes are the same color as the exhausts. You'd think the intake valve heads would be significantly cooler than the exhaust valve heads, but maybe both are enough warmer than the rest of the combustion chamber to show the white ash deposits rather than the black carbon on the rest of the chamber.

The part that threw me a curve is your comment that it is not a turbocharged engine. I was ready to blame leaky turbocharger cartridge seals introducing oil into the intake as the source. Without a turbocharger there, I'm a little at a loss to figure out how the oil got into the intake. If it was an older grader, I'd blame overfilling the oil bath air filter. Judging by the head though, I'd say this one is new enough to have a dry paper element. I'm wondering where that oil in the intake might have come from, as I bet that is the source of your consumption and the unusual color of the valve heads.

Pete.

which was typed while I was typing mine:

Since this a non-turbocharged engine and likely has a dry paper air filter element, we don't have the turbocharger pressurizing the intake. With a properly serviced air filter element, I wouldn't think any appreciable vacuum would be pulled on the intake. I imagine the air filter could have gotten plugged, although knowing Dpete and how he services his machines, that isn't likely. Even if it was run with the air filter plugged for some time, and that might pull some oil past some worn guides, I'd expect that oil would be limited to showing only around the intake port and valve head of the guides which were leaky. There really shouldn't be a way for any oil leaked past an intake valve guide to work its way upstream inside the intake manifold.

I'm still confused by the oily inside of the intake manifold and think that might be the source of the color and the consumption, just don't know where it could be coming from.

Pete.

If the valves have become carboned up through a long service life and oil is going down the valve guides there will be some blow back past the valves pushing oil back in the intake. I don't see a big problem, carry out a head overhaul including changing the valve guides if they are worn and put it back to work.

Woops-the non-turbo info came out while I was typing too-that's what you get for assuming huh? Worn guides can be the cause in that engine. Some engines will "spit back" just a little during valve overlap, so that may explain the oily intake...I dunno...

That's a direct injection NA engine which is somewhat prone to deposit buildup on the back side of the intake valves. These deposits can effect valve sealing, leakage and cooling. Oil additives containing Calcium, Zinc and Phosphorus combined with modern low sulfur fuel formulations are most likely the deposits noted. A high rate of oil consumption will aggravate the condition.

Valve guide clearance, ring seating, oil ring condition and drainage would be the suspect items for high oil consumption.
What lube oil are you running and are you using a bio-blend diesel fuel?

"Garlic wrote:

I imagine the air filter could have gotten plugged, although knowing Dpete and how he services his machines, that isn't likely.

Could be something that happened with a previous owner though I have no idea how long he's had the machine. My bet would be that once that coating forms it's probably going to stay there until removed mechanically - ie it could have been there for some years.

I wouldn't worry too much about it, just make sure the valves and seats are cleaned up and seal properly.

OM it is a glow plug engine, Delo 400 15w/40 and Chevron fuel. I've had it 10 years no telling what happened previously, first time having the head off. We are going to check the injection pump timing just for drill

Ok,
Long production run on that model (61M?) 1974 to 1997. Yours would be pre 1981.
Don't see anything unusual about your choice of oil and fuel.

Correct 1980, 61M7378

I have seen this before on the D6C 4.75" bore engines and turbocharged units. N/A engines run a higher combustion temp than lower rated turbo units due to a higher fuel to air ratio and can leave more deposits on the valves. It doesn't burn off and needs to be mechanically removed.