Stuff in my coolant tank??

[Beardy_John]

Hi clever people!

I have a 1.8 Vx with 17k miles and looking at my 7 this week, I noticed some dark stuff in my coolant tank. Tank was fresh on in May during a trip to Team Leos.

With the engine cold, the stuff in it looks like sediment rather than oil, as it's sitting round the bottom of the reservoir. If this was oil, would it be more of an emulsion??

Has anyone seen anything like this before? My first panic was the head gasket, but I'm not so sure now. I was going to flush it through but I wondered if those with a lot more experience might know what it is?

Thanks in advance,
John

[Jonathan Kay]

Yes, that doesn't look like oil in coolant, which is typically an opaque emulsion. 

There is a chemical test for products of combustion in coolant if you have any other reason to suspect head gasket failure.

Did you flush the system before the work in May?

Did you use premixed coolant, and if not was the water particularly hard?

Jonathan

[Beardy_John]

Hi Jonathan,

When the coolant tank was replaced (due to cracks) we didn't empty the whole system, just drained the bottle, swapped it and topped it up. The type/mix was what the Team Leos guys had on hand. Hadn't thought of hard water rather than distilled. 

I think I will give it a flush through this week, refill with new Comma and distilled water/premix and see how it responds.

Thanks!

[Jonathan Kay]

That's what I'd do. Except that it would be premixed.  : - )

Jonathan

[ScottR400D]

Definitely premix. 

[ECR]

Rust or sand from the waterways in the block perhaps

[Beardy_John]

Scott R400D - agreed, one less variable to contend with. Will get some tomorrow when I'm out and about.

ECR - I'm hoping that's the case. It did have a long blast down to Le Mans for the Classic at the end of June. 2 long days of driving there and back may have loosened something up.