Foam inside coolant

[StiflerMR2]

Hey all,

I hadn't moved the car in a while but decided to head out with the wee man yesterday. I opened to boot to stow the roof and noticed there was a fair bit of what I would call foam / froth inside the coolant tank.

Is this anything to be concerned about? Is it just a side effect of sitting outside for a while? FWIW the car drove fine, temp was constant but it was still there when I got back.

Any ideas chaps?

[Dominic]

Have you changed / topped up the coolant recently?

[Stephen]

The k series can suffer from both HGF and condensation. If it has not been moved or run for a while it may just be condensation. Have you lost any water, how does the oil look and is it overheating? It's also worth making sure that the oil cap still has an "O" ring fitted.

[StiflerMR2]

Nope, not been changed since the Alloy rad went in during January 2015.

Temp was a constant 79 on the run but I wasn't going mental as I had the wee man in tow. Water level looks fine, forgot to check oil, will do that tonight!

ETA: just checked the oil level and it is spot on, oil is a nice golden colour and no signs of scum around the oil filler cap.

Foam is still there however

[robin]

Did you wash the coolant tank in fairy liquid

[Stephen]

Just thinking condensation occurs on the oil side. So my previous posts are incorrect.

[StiflerMR2]

That's what it looks like Robin!

[robin]

I suspect it's one of two things:

(1) Either the cheese that is sometimes caused by mixing different types of coolant (and/or mixing certain coolant types with too much air).
(2) An emulsification of the oil & coolant caused by, probably, a oil->coolant seal failure. The most obvious of these is the elastomer failure in the classique Elise head gasket. It could also be failure of the seal at the bottom of one of the liners. It is likely to be a place where oil pressure is pretty high because otherwise you would get coolant->oil rather than oil->coolant. For that reason I am more inclined to believe it to be elastomer failure.

Cheers,
Robin

P.S. It emulsifies when it gets whipped up by the water pump and then floats on top of the expansion tank as that's where the coolant is typically sent to when the stat is closed.

P.P.S. It could be the legacy of a previous failure that's long since been fixed if the grungy stuff was trapped somewhere, e.g. in the rad, but the car had been allowed to stand for a long time and it all collected in one place.

[StiflerMR2]

Thanks Robin.

Think a call to Craig is in order tomorrow morning!

[robin]

It might be worth scooping some of the gunk out (perhaps also bring along a bit of the liquid). Stir it all up, mix in some table salt (you can put in as much as you like) and then let stand somewhere warm. If it is a coolant/oil emulsion I think there is every chance that as the salt falls out of the mixture, the chemicals will split and you should end up with oil floating on coolant (with salt in the bottom).

Or you'll end up with salty cheese

Cheers,
Robin

[Dominic]

I suspect it's one of two things:

(1) Either the cheese that is sometimes caused by mixing different types of coolant (and/or mixing certain coolant types with too much air).
.

That's what I was wondering... Looks familiar to the mixture I inadvertently concocted when I used the wrong coolant... Which is good for blocking rads and subsequently toasting the engine.

[StiflerMR2]

Thanks Dom, the coolant shouldn't have been changed since the rad change over a year ago. Like I said, temp was constant and no signs of anything in the oil

TBF, I've had 4 K series elises and never had HGF, so if it is that, it's only fair I suppose (would still rather it wasn't as trying to move house atm so unneeded expenses are not welcomed!

[robin]

I would start off by removing the gunk from the tank and then seeing if it comes back ...

Cheers,
Robin

[StiflerMR2]

I'll try and siphon it out tonight....not sure what to use however!

[Stephen]

Take the header tank off and wash it out. As it's the highest bit of the system you shouldn't loose much coolant.