Aux rad area coolant leak

[alastairg]

I have had a persistent coolant leak for over 6 months. With normal daily driving it is minimal. But it can be significant if I stress the cooling system (hard and or long drives) enough to drop the level from max to min in a few days.

Car has had new main radiator (end last year) new auxillary rad (2004) new after run coolant pump (last year) most of the coolant pipework renewed during my ownership (last three years).

All clips tight.

At present and all along the only area always to have evidence of dried coolant is the 3 way piping to the aux rad. This pipe was new end last year (previous one had split, you could see it weeping coolant ,wrong side of clip !!) and I thought I had solved it.

It passes pressure testing at dealer but clearly under pressure coolant is getting out. Could the rad have a small hole/split or would this be obvious ? I have spent time with the engine on after a long run trying to see a leak but no luck. The underside of the lower aux rad pipe has been damp but no more than that. I have repositioned that pipe and replaced clip.

Could this be an air lock ???

It seems worse when A/C on. Does that change coolant pump speeds ??

[Greg_S]

Putting the aircon on wont change the coolant pumt speed since that is driven by the timing belt. Just changed my aux rad because it had a small leak, could only tell because it had got discoloured in places

[AAH!]

Faulty filler cap?

In theory the cap should rattle when shaken, which shows the pressure relief valve is working. Maybe the valve is stuck open?

Cheap to replace from Haulfrauds.

Angus

[afhgus]

what about the expansion tank. Mine had a split near the hose bit. Had to get a new one.I have heard also that they can use some water and the air con uses a bit??