Gloopy coolant!

[eltax91]

Chaps

Just got my spare toy back for. My MiL who has had it on loan for 2 months, doing a sub 1 mile journey twice or 4 times a day.

Decided it was time I checked the levels and when I opened the coolant header tank I found a brown goopy liquid in it. Almost like the colour of caramel. There is no evidence of mayo under the oil cap and the oil level is ok. It loses a touch but that's pretty much found on the floor!

So, is this the disaster I hoped would never occur and has the car suffered HGF? Or something less sinister?

I bought the car in march from a fellow PH'er who had it stood for a while deciding what to do with it following someone making it a cat c write off.

Car is a 124k mile mk2 1.8 mx5.

[Mave]

I'd give it a coolant flush and change (especially if you don't know how fresh the coolant is) and just keep an eye on it.

[Aphex]

Check your oil cooler as maybe you have oil entering your coolant

[carreauchompeur]

Meh, if it's leaked a bit and has been refilled with water then it's probably just gone a bit mouldy. The water in my M3 does similar, quite a few people have the same issue.

[eltax91]

Aphex said:

Check your oil cooler as maybe you have oil entering your coolant

Thanks for the info. I've just done a bit of research on this and see what you mean. A sandwich affair sat between the block and the filter with coolant in and out nossles.

It seems like its cheaper to get an radiator based oil cooler performance kit than replace the oem part!

Any idea how I go about testing it to see if its leaking? Car is due and oil change anyway so might as well remove and inspect it at the time.

[GC8]

Have you considered mixed coolant?

Broadly: if you mix red and blue coolant then this can be the outcome.

[SLCZ3]

I would suggest a full flush of the cooling system, sounds like its been stood and the coolant is not inhibiting corrosion, as it should do, also get a couple of packs of cert seal in case, I always found it to be the most successful leak sealent in the days of yore.

[eltax91]

SLCZ3 said:

I would suggest a full flush of the cooling system, sounds like its been stood and the coolant is not inhibiting corrosion, as it should do, also get a couple of packs of cert seal in case, I always found it to be the most successful leak sealent in the days of yore.

Is cert seal a rust inhibitor, or another version of k seal?

[GroundEffect]

Coolant tends to go brown when it's been overheated - beyond about 170C. If you haven't had your HG go, then it's difficult to see what else it could be.

[eltax91]

GroundEffect said:

Coolant tends to go brown when it's been overheated - beyond about 170C. If you haven't had your HG go, then it's difficult to see what else it could be.

Hmmm. Interesting one. It hasn't boiled up in my ownership. The MiL would had told me if it did it to her (assuming she noticed), but it's possible.

Will have a go at a proper flushing and remove/ examine the cooler and take it from there I guess.

Say it is worse case, how hard is a head gasket to DIY?

[MG CHRIS]

It wont be the headgasket it just where the coolant as either just been topped up with water and rust has built up inside the water system. The rads on mx5 are common for gunking up flush it out and refill with 50/50 mix of antifreeze and water should be ok.