Has your engine coolant ever changed colour?

[Bav34]

Volvo 2020D. Engine coolant. It never leaked or overflowed or froze so apart from normal maintenance checks I ignored it. I couldn’t see the point of changing it but the world has changed and along with our cars brake fluid we have to change the coolant every two years ... or so.

In 2015 I had a burst of enthusiasm whereby I changed and threw away a perfectly serviceable saildrive gasket that looked and felt exactly like the new one, and decided to drain the coolant.

It was red . No idea why.

I drained the block using the plug on the side, ran fresh water in using our shower head, waited for clear water to appear, put the plug back in, ran the engine under load 3 times, half an hour each time, draining and refilling.

Our neighbours were delighted

Block water now the colour of tap water, drained it, put in the only coolant the local Volvo agent had ... YELLOW VCS. Apparently older engines like mine should have green coolant but yellow was all he had on his shelves and he knew the model variant.

Today I drained the coolant.

It’s deep pink!

Any ideas and has it happened to your engine?

Confused

Yellow by Twenty Seventeen, on Flickr

Pink by Twenty Seventeen, on Flickr

 

[RichardS]

The only similar experience I have had is that some coolants I've used, particularly the OAT ones, have some sort of luminescent component in them, a bit like the fluorescin we used to use in the chemistry lab for tracing light paths through liquid. Sometimes these look yellow/orange when you look at them in the bottle but when you look at them diluted in the header tank it looks pink/brown.

Richard

 

[Slowtack]

Apparently mixing some different coolant types can cause the cooling system liquid to gel due to reaction between the inhibitors. Lots of info on line. You may need to flush the system completely.

 

[RichardS]

Apparently mixing some different coolant types can cause the cooling system liquid to gel due to reaction between the inhibitors. Lots of info on line. You may need to flush the system completely.

I don't actually believe that any mixture of coolant types on the market during the last 10 years or so will cause any problems but, in any event, the OP has done enough flushing to ensure that even if he was using 20 year old coolant there would be no problem anyway.

Richard

 

[Yngmar]

Is there a calorifier in the system that may have hidden away some of the old coolant and escaped flushing?

 

[Bav34]

in any event, the OP has done enough flushing to ensure that even if he was using 20 year old coolant there would be no problem anyway.

Richard

How true but the first tap water flush just resulted in slightly diluted red water ... it took the third flush with 1/2 an hour, in-gear, 2500 rpm running to get a clear flush.

Is there a calorifier in the system that may have hidden away some of the old coolant and escaped flushing?

Interesting thought thanks, yes there is a calorifier and due to a blockage in the water pump that feeds that circuit (fact established today) there would have been SOME red possibly mixing in with the yellow but the ratio would be very small.

The engine takes 2.9 litres of coolant, I would be amazed if there was enough water in the (non-circulating) pipes to change yellow to such a strong pink.

And that is the issue really, a small amount of red possibly in a large amount of yellow producing such a strong colour.

 

[aquaplane]

The colour in antifreeze used to be a pH indicator to tell you when the glycol had broken down and gone acid. The inhibitors usually included a buffer but not always. Anyway, if your coolant has changed from yellow to red, it could be a pH thing. I wouldn't expect it to change in 2 years though. I have used blue antifreeze in my car for much longer than the recommended couple of years and never seen a change in colour.

The "modern" red OAT antifreeze is supposed to be good for longer than the old blue stuff.

 

[Carmel2]

Did you change the filler cap for a new one?

 

[<152587>]

Vp issued a service bulletin concerning this anti freeze, from memory, about 2010. Seem to remember it was permitted for use in a few of their newer engines and definately not in any situations where conventional anti freeze has been in use.

 

[Bav34]

Did you change the filler cap for a new one?

No, do you think that I should, is it a service item?

The colour in antifreeze used to be a pH indicator to tell you when the glycol had broken down and gone acid. The inhibitors usually included a buffer but not always. Anyway, if your coolant has changed from yellow to red, it could be a pH thing. I wouldn't expect it to change in 2 years though. I have used blue antifreeze in my car for much longer than the recommended couple of years and never seen a change in colour.

The "modern" red OAT antifreeze is supposed to be good for longer than the old blue stuff.

My engine appears to need green. I may be looking at an Oxalic acid, or similar, flush.

Vp issued a service bulletin concerning this anti freeze, from memory, about 2010. Seem to remember it was permitted for use in a few of their newer engines and definately not in any situations where conventional anti freeze has been in use.

Oh dear. The Volvo agent in question was in Cherbourg and yellow VCS was the only one he sold so I guess a lot of older engines are being contaminated over there.

 

[Carmel2]

Re the filler cap, I replaced mine as the spring wasn't up to it after 15 years. The new one had reddish/pink grease on it to stop it rusting on the shelf, and when that came into contact with the coolant it turned the colour you have in the jug.

 

[<152587>]

Vp issued a service bulletin concerning this anti freeze, from memory, about 2010. Seem to remember it was permitted for use in a few of their newer engines and definately not in any situations where conventional anti freeze has been in use.

If you search Volvo Penta VCS and pick up on marinepartsexpress the bulletin is free to read.