bit of a dumb question....if i can see fluid in the header tank (one with the metal cap) does this mean the rad has enough coolant in it? the reason i ask is because there are no min and max markings visible on it. The overflow expansion bottle near the battery should not be used as a gauge of coolant level or have i got it wrong? where should i be topping up - in the header tank? (metal cap) thanks

 

This is on a classic shape car, yes?

With the engine cold, the header tank (one on the inlet manifold with the metal cap) should be absolutely brim full. Simply "being able to see fluid in it" isn't enough, as if there's any significant air in the tank the system won't pressurise properly. The expansion reservoir by the battery should be topped up to somewhere in the middle of the high and low markers.

If it was lower than that, check it again after the engine has been through a full heat cycle (i.e. got hot and allowed to cool again). Top up again if necessary and repeat until the level has stabilised.

 

ive never heard of any one filing upt he over flow but yeah the rest is sound

 

...see this is what i'm confused about. some people say top up through the overfill and others say dont fill up through there as its just an outlet for excess coolant?

 

when your doing a coolant change pour into the header tank to refill the system what ever the engine doesnt need will then be circulated to the reservoir next to the rad which should be between min and max after a run and has been left to cool if its below the min mark top up the reservoir easy.

 

yep that the one but hay let it cool down first lol