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Chasemmc
07-08-2017, 11:45 AM
Having been focused on the cooling system for the past few weeks, I have been reading about how to flush the core. The pix on 71's are interesting but the heat exchange does not match the 8v92ti's on my 56. I researched the past threads, but am not feeling comfortable tearing it apart at this point. (My prior mechanical experience is limited to changing the spark plug on my mower).

Upon removing the fill pressure cap on the port side, instead of antifreeze it had a black layer. I of course, being the mechanic I am, poked it with my finger. It was a thin brittle layer, similar to the top of a creme brulee (in a good restaurant - very thin). Rubbing between my fingers it turned into a black fine coating sort of greasy. Underneath was the green antifreeze.

Oil looks good, no frothing or light brown discoloration. Engine temps are 180 at 1500rpm +/- 3.

So I searched prior posts 2009 and I got the impression that the green stuff is not the recommended DD but should instead be Power Cool. Also in that thread they stated the crust could be the mixing of incompatible brands of coolant.

So probably a complete drain, flush and replacement is in order as well as sending off an oil sample to look for antifreeze. Mike P states their are testing strips that might help in an initial diagnosis.

What do you all think. Am I tilting at windmills, or should i not run that engine until some remediation takes place.

As always, thanks in advance for your expertise.

Mark

barkdee
07-08-2017, 12:40 PM
I purchased a project boat with 892s and had a similar layer of black soot like stuff on the coolant surface of one heat exchanger. It wasn't solid, just a floating thin layer. Of course I thought it was oil in the coolant and went through testing everything that could leak oil into the coolant. Found no leaks. Flushed out the heat exchanger twice using dishwashing detergent -with engine runs to temp in between. Filled with water and Pencool and haven't had a problem since. My suspicion is that a rust inhibitor of some type was previously used in the coolant and that had created the black soot.