Wrong Coolant Cap?

[finestjammy]

Hi All

Following on from my car dumping its coolant the OPC advised checking the level once the car was fully cold. I've done this and it was low, took just shy of a litre to bring it up to the max level. All seemed fine until giving it a poke in second gear and I could hear the hiss of the expansion tank in the rear. Is this just venting any excess? I attach a pic of my coolant cap and I think it might be the wrong one as there appears to be no release valve?

Any thoughts?

[cd1957]

Hi Finestjammy, that looks like the Cayman one in the boot, the pressure cap is on expansion tank, under rear carpet covering the top of the engine.Top up the engine one with the one in your picture fitted, does not matter if its slightly over filled, as it should drain out the excess.

How much coolant did it initially loose, as it may need a full drain and bleed with Vac system

Chris

[finestjammy]

cd1957 said:

Hi Finestjammy, that looks like the Cayman one in the boot, the pressure cap is on expansion tank, under rear carpet covering the top of the engine.Top up the engine one with the one in your picture fitted, does not matter if its slightly over filled, as it should drain out the excess.

How much coolant did it initially loose, as it may need a full drain and bleed with Vac system

Chris

Thanks for that. Yes, the picture is the one that was in the boot next to the oil cap. So is it the right cap do you think for the boot one? It initially lost all its coolant, spring clip went on one of the hoses, and had to be recovered to the local OPC. They drained and bled it I believe. I topped it up right to the max line when it was stone cold. The hiss might have just been the system venting the excess I guess as you suggested. Just gave me a fright when giving it a poke in second gear and heard the hiss from the rear

James.

[Rockster]

finestjammy said:

Hi All

Following on from my car dumping its coolant the OPC advised checking the level once the car was fully cold. I've done this and it was low, took just shy of a litre to bring it up to the max level. All seemed fine until giving it a poke in second gear and I could hear the hiss of the expansion tank in the rear. Is this just venting any excess? I attach a pic of my coolant cap and I think it might be the wrong one as there appears to be no release valve?

Any thoughts?

Post a pic of the other side, the side with the part # on it. The part # should end in 02 or 04.

The white residue is dried anti-freeze. Looks like the cap might have been leaking. The cap can require more force to fully tighten than one might think. Are you sure you screwed the cap down securely?

[Bennachie]

The actual tank cap, the one you can't see in the engine bay is known to weep coolant unless it is in perfect condition - you get what appears to be a 'mystery' leak.

[finestjammy]

Rockster said:

finestjammy said:

Hi All

Following on from my car dumping its coolant the OPC advised checking the level once the car was fully cold. I've done this and it was low, took just shy of a litre to bring it up to the max level. All seemed fine until giving it a poke in second gear and I could hear the hiss of the expansion tank in the rear. Is this just venting any excess? I attach a pic of my coolant cap and I think it might be the wrong one as there appears to be no release valve?

Any thoughts?

Post a pic of the other side, the side with the part # on it. The part # should end in 02 or 04.

The white residue is dried anti-freeze. Looks like the cap might have been leaking. The cap can require more force to fully tighten than one might think. Are you sure you screwed the cap down securely?

The part number is 987 106 044 00. I have actually ordered a 996 106 447 04 but I think now that this is the cap under the engine cover, not the boot cap. I'll check again that it's super tight. As I filled it to the max level when it was stone cold I have a feeling it's just expanded and the excess is escaping. I'll keep an eye on it though.

[finestjammy]

Panic over. I think I just overfilled it a little. Went to check now and when I uncrewed the cap it overflowed. Sitting right at the top of the neck now. I guess it will continue to release a little more once it's hot until it finds its level.