Coolant Tank Scum

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RHY 11S

Original Poster:

78 posts

218 months

Monday 7th April 2008
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Yesterday I noticed in the coolant tank something which looks the scum you might see on a dirty river. Is this what is referrred to as Mayo? - it certainly doesn't look like anything I'd put in my ham sandwiches!

Had a look at the oil cap and the coolant cap and can't see anything that looks like Mayo.

The car recently struggled to get through its emmission test [although a failed lambda sensor seemed to be to blame] and has been hunting a bit on idle when cold.

Any ideas anyone? Thanks.

It's a Mk2 111S with a K-Series engine.

RHY 11S

Original Poster:

78 posts

218 months

Tuesday 8th April 2008
quotequote all
Just had both the chemical test and a pressure test and both came back negative. Car seems to be driving fine, although it hasn't seen anything above 4000rpm!

Garage made a very good point which is that the coolant itself is perfectly clear. There are no signs of oil on the surface nor bits of residue in it. All I have in there is this scummy residue that looks like dirty river scum. This doesn't seem to be oil either - more like a clear liquid.

Can I relax now and just assume that something may have got into the system when I had some recent work done?

RHY 11S

Original Poster:

78 posts

218 months

Wednesday 9th April 2008
quotequote all
Well, she's driving like a beaut so I'm happy! Coolant level hasn't moved and temperature is steady as a rock?

I'll try and rinse the expansion bottle out this weekend and see if any scum returns.

Thanks for the input everyone.