"black" coolant anti-freeze

[robymayway]

Is it possible that the "MUD" is actually oil that separated out when left to stand?

Craig

I don't.
Is not oil

[MikeP]

I've have been doing some research and i have found that mixing non-compatible types of antifreeze can produce brown sludge like what you are describing. Perhaps someone previously added coolant/antifreeze that was not compatible with what was in the engine.

I would suggest you drain all the coolant completely, thoroughly flush the system with pressurized water and, if possible, flush the system in the REVERSE direction that water usually flows. I don't know about that particular engine but on an 8V71 it is difficult to get all the old coolant out using the drains that are easily accessable. So it's important to ensure that you get fresh water running through all parts of the engine.

After THOROUGH flushing, refill the system with coolant approved for the engine. I'd bet that will solve the problem.

[robymayway]

thanks Mike
It seems a good idea.
I have found a very old forum that told about this problem and they said that it was an algae...do know something about this matter?

[MikeP]

I've never heard of algae causing a problem in an engine cooling system. For no other reason, algae needs light to grow...Though I'm no expert on algae. Maybe some type doesn't need light.

[robymayway]

I've never heard of algae causing a problem in an engine cooling system. For no other reason, algae needs light to grow...Though I'm no expert on algae. Maybe some type doesn't need light.

maybe... however your reasoning is correct!

[saltshaker]

Drain all the coolant, fill with fresh water only then run engine for about 15 mins. Drain again and then fill with a Detroit Coolant flush. I used a 2 part flush that I got from my local Detroit dealer, can't remember the name. Follow instructions for the flush. Flush with water again once finished, drain and fill with the proper antifreeze for your engine.

[MikeP]

With all this sludge I think it's really important to try to reverse flush the cooling system, if at all possible, to ensure you get everything out of there...

[Genesis]

Drain it all NOW.

Flush VERY VERY VERY well.

If you have incompatable AF types in there you're in trouble if you don't get it out before it plugs up some of the smaller passages in the engine.

This sounds like EXACTLY that problem.

[robymayway]

really thanks to all !!!!!

only a little thing : in Italy The hatteras yacht is really a legend.

ciao
roberto

[REBrueckner]

I agree...if poster is sure its not oil, incompatible antifreeze is likely culprit...after cleaning use a DD approved, heavy duty, low silicate antifreeze ...
and keep a few extra gallons on board for compatible refill....

after the initial drain of sludge and crud...., refill with fresh clean water....run the engine until the water in the heat exchanger is warm....it will circulate slowly even when the thermostats are not open....do NOT run until engine gets HOT...just warm.....drain again and if the drained is still dirty, do it again....

There are likely five drain petcocks on each engine....open them all.....