Based on my many experiences with same, that's typical of what oil in your coolant looks like when you have a bad/failing head gasket (looks like hot chocolate.)

A compression test only tests cylinders ability to hold pressure and WILL NOT detect a head gasket leak that merely allows oil to get to the water passages.

Remember that oil pressure is higher than coolant pressure and will force oil into the coolant except when engine is off, so when the gasket leak gets really bad, coolant under pressure after you stop but while engine is hot, will get in your crankcase oil when engine is off and will look just as bad, so keep a close eye on your oil as well, and be prepared to change head gaskets and check your heads for warping since hauling a boat or heavy load, more stress on engine, everything runs hotter, clearances change, might warp head (especially aluminum) and/or allow leakage in a marginal gasket. Oil+water makes neither good coolant or lubrication, likely cause you lots of extra headaches if you don't catch it.

 

+1, i think that's oil. nice explanation, cpu, about oil pressure being higher.

 

If you do have to pull the heads of get some new casting clearwater heads.

 

Honestly, looks like dog food.

Looks like caked over crap left from a radiator or heater core stop leak product...

 

Great explanation cpudog. I did put some new clearwater heads on about 10 months ago. I was super careful on assembyl. Torqued EVERYTHING to spec. So maybe its just a gasket failure. The heads are still under warranty so if I take them off I'll be able to see if they are warped or not. looks like another day in the garage plus $100 in gaskets and bolts.......

I used the Felpro perma torque gaskets. I called Felpro and they recommended the Felpro 519SD which if the perma torque plus extra goodies in the material to make it SD (Super Duty). Anyone use these??

 

I would be curious just where pressurized oil even comes close to a coolant passage.... Heads receive oil up thru the pushrods, and while that is kinda pressurized.... it basically vents directly to atmosphere. (under the valve covers though....) There isn't any pressurized oil passing thru the head gaskets at all. Blown headgasket will see see coolant in the oil, but, not the other way around.

 

the man stated "I'm losing a cup or so of coolant a week"..

it's gotta be going somewhere.. is there zero pretty white smoke at your tailpipes?

I'd be looking at freeze plugs real close like, and especially the ones tucked away out back..

also- what ratio of coolant to h20 are you using? what is it at this point? not that pure coolant EVER looks like that, but.....

new radiator? what is it made of? Sometimes, different metals react to different solvents in a corrosive way.. if it was somehow coated in any manner, you could be seeing that coating in globs..

I interjected the alcohol and/or ammonia thing w/o explaining myself- if'n you or someone trying to be 'helpful' poured washer fluid in the overflow basin, you'll get precisely what you see in those pics.. I know this beyond doubt, as one of those 'helpful' 16yo ***** at a jiffy lube decided it was a good idea to interchange basins on me one day.. I flushed at least 10 times both directions to get that crap out.. I'm not exaggerating..

 

I believe that is why most everyone was recommending multiple tests.

 

Me too! +1 If we had an engine oil cooler in the rad then this is more likely.

 

My wife did this in her Grand Cherroke.. Decided to put washer fluid in.. but she put it in the coolant reservoir tank. Lucky I caught her before she cranked up and was able to drain it out and refill the coolant.

And I never had this in my main Rad; I know my Heator core was plugged up with brown crap.. I back flushed.. and did 3 flushes on.. I did notice in my reservoir tank at the very bottom some gunky crap that looked like Chocolate milk.. No loss of coolant.. no smoke..

Just something that was at the very bottom i sucked out with a hose the last time i flushed her.