Engine coolant

[Wavey]

On holiday on the boat and checked oil and coolant just now before heading to Poole tomorrow. Starboard engine coolant level ok but coolant is black in colour. Any idea what could cause this? Doesn't seem to be any oil content. Engines are Yanmar 6LY. Thanks.

 

[Wavey]

Just checked again and it's actually something in the top inch or so of coolant. Below that it's fairly clear, so it seems there's some sort of residue close to the surface. Still no idea what it is.

 

[Momac]

If you google yanmar coolant black it finds an old ybw thread on the topic which suggests it's not a big issue.

 

[Latestarter1]

On holiday on the boat and checked oil and coolant just now before heading to Poole tomorrow. Starboard engine coolant level ok but coolant is black in colour. Any idea what could cause this? Doesn't seem to be any oil content. Engines are Yanmar 6LY. Thanks.

Ignore any suggestions from the PBO side, yours are not little puddle jumper engines, it is a big issue your heat exchanger/manifolds cost big $$.

If coolant is black could be combustion contamination but get it changed, use only Yanmar own coolant or Texaco Havoline ELC (XLC Orange) which is what Barrus dealers use and far less expensive than Yanmar's own. Cynically I wonder which they charge out for when dong a coolant change?

 

[Wavey]

Many thanks LS. Combustion contamination was my concern but I'm not an engineer by any means. Coolant was changed to XLC Orange in Jan 2014 as I wasn't certain what was in there although previous owners seemed meticulous. Will get it changed asap and monitor.