Coolant level variation, all over the place

[The_Dr]

So the coolant level on my brand new car, a SS1600 (Sigma 275), is varying a lot from week to week.

It was at Max when I picked it up, then when I checked the following week it was at Min.

Topped it up, and then the week after it was way over Max, almost brimming, so took some out.

Now this week it's back down way below Min again. It's all over the place !

Can't see any leaks, checking when cold. Is it meant to vary with heater use maybe ?

[SM25T]

No variation with heater. Heater valve should be open (on) when filling and bleeding the coolant, to ensure no airlock there.

[GulfSeven]

Sounds like an airlock if it's varying that much when cold.

If it goes up to the top when hot I'd say it's likely to be a faulty cap.

I think it can vary between min and max if you compare cold to hot when working correctly.

[Jonathan Kay]

As above.

Jonathan

[The_Dr]

Ok, thanks guys.

It's going in to Caterham Gatwick next week for the first service, will get them to check it out.

[ScottR400D]

Don't let them tell you that "they all do that"! 

[The_Dr]

So at Gatwick they drained the system and checked it all out. They reckon that it was all fine and no air lock. We shall see over the next couple of weeks.

The Gatwick service team were actually very good. I arrived just after 7am (had to get around the M25), and by 7:45 the service guy was already there and they started work on it. They fixed a couple of things and by midday I was on my way. 

 

[alcal]

My Roadsport 140 has always done this in the seven years I have owned it. The level goes up after hard use then down again after pottering. There are no leaks and I came to the conclusion that air is being entrained in the system at high revs then making its way out with gentle use. I haven't yet heard a more plausible explanation!