"black" coolant anti-freeze

[robymayway]

Hi to all.
I 've got a 37 c 1981 with 2 DD325hp that sound very well except for a new problem of over heating temperature ( left 190 and right 195/198 ).
I don't think it could be a problem with headexchanger obstruction as I clean them perfectly last year.
Now the surprise is that the coolant blue became grey/black.
I put a little bit of liquid into a Coke bottle and after 5 hour the surprise: 1/4 black mud and 3/4 return to be perfect blue coolant.....
I desume that all coolant way into the motor are obstructed of mud.
What do you think about ?? Help me !!!!!!!!!!!!!!!
an italian hatteras in love.

 

[robymayway]

please suggest me how clean mud from coolant system and how avoid to accumalate mud in the future.
ciao
roby

 

[MikeP]

Are you saying that the "mud" is in the raw water portion of the cooling system (the part that picks up seawater and circulates it through the heat exchanger and then back out through the exhaust) or in the circulating portion of the cooling system (the part that contains coolant/antifreeze)?

If the raw water system picks up mud or sand, it cannot get into the coolant portion of the system unless there is a serious problem with a broken or cracked heat exchanger.

 

[REBrueckner]

Very difficult to diagnose problems via vague descriptions like this...I'm not even going to try....
mud color coolant...
was the circulating coolant changed last year??...and was clear blue at that time...is this DD approved heavy duty diesel antifreeze....or is it coolant??
Did you pour off the blue clear antifreeze and inspect "mud" what does "mud" mean?? thick oozy muck..... or are you describing a black color to otherwise blue normally viscous coolant?? Is the coolant circulating??

overheating....two engines overheating this year when they operated ok last year?? Was this after winter shutdown and winterizing? Did you check raw water impellers?? has the boat been hauled....could outside growth be obstructing engine intakes? Coolant at normal full level in each engine? Do you have jelly fish there which might clog intakes? Did a yard paint over your pinhole engine intake strainers??

General question: what other work was done on the engines prior to this problem....

 

[aquacraig@shaw.ca]

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

Craig

 

[REBrueckner]

Oil in your fresh water system will accumulate on top of the coolant in your expansion tank....stick a finger down through the pressure cap opening and if it comes up black, yea it's oil....but why would that happen in both engines simultaneously?? that's one reason why I asked what work has been done recently on the engines....

 

[robymayway]

no extra job have been done on motors.
The sludge is not oil and I saw it because the plastic hose connect at pressure cap of expansion tank arrived into a plastic bottle that I have placed to keep clean the engin motor roof

 

[robymayway]

last year I have only cleaned head exchange with correct product ( DD authorized mechanic) but I have not change the coolant antifreeze

the sludge is only into the circulating portion of the cooling system ( the part that contains coolant / antifreezre )

 

[robymayway]

impeller have been correctly change one week ago and work correctly,
intake have been cleaned with my first swimming
strainer are cleaned

when I ship at 2100 rpm
both headxchange are cold
probably there are no circulation of coolant

My doubt was if sludge may closed the coolant sistem causing overheating temperature

 

[robymayway]

Oil in your fresh water system will accumulate on top of the coolant in your expansion tank....stick a finger down through the pressure cap opening and if it comes up black, yea it's oil....but why would that happen in both engines simultaneously?? that's one reason why I asked what work has been done recently on the engines....

no oil in the expansion tank
only sludge black. I left a bottle of coke full of coolant and after 5 hours 1/4 of sludge on the bottom and 3/4 of cleaned coolant on the top

 

[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.....