Coolant level drop

Hi again everyone, I've checked my coolant this morning when the engine was cold and it is about 10mm below the minimum mark after being on the max mark on Sunday afternoon. The car had used absolutely no coolant driving it back from Manchester to Norfolk on Saturday so it must have lost approx 1.5 litres in 2 days! In those 2 days I have done about 50 miles mid range stuff admittedly opening her up a bit but not going too mad. The oil level and filler tube is all OK, temp has hovered around 80, and no oil in the coolant so I can only think it's the header tank or a tube split somewhere. Any other ideas? Cheers, Alex

It could be the header tank cap (doubtful). Check if the cap part number ends in '1' if it doesn't then it's the old version and should be your first port of call. If not, then very likely its the header tank that has cracked (common fault) get a new one from Eurocarparts and get an indi to fit it.....it's not more than 2 hours labour. Good luck

The cap number ends in 00 so I guess it's the old one. From what you've written Rodney it sounds like the 'header' tank is the same as the tank that I fill up with the cap, is that right?

The very same. Try the cap, either way a new coolant tank doesn't come with a cap, so you might as well get the new one. Remember you can't just top it up and drive away, the system will fill up with air bubbles and may bubble over. Try lifting the small silver tab virtically, (it 'rests' above the black square box on the coolant tank) for a day after you've topped up. If possible you should rev the engine (4+k)whilst topping up, then drop it to around 3k revs and get someone to close the cap.

As Rod says, change the cap anyway - they are only a few quid. If the cap is leaking, you should see some signs in the catch tray on top of the tank. From there it drains down a tube to the underside of the car. It the tank is cracked (or pinholed) you should see evidence on the engine compartment directly under the tank. They usually leak on the back side of the tank, up against the wall of the engine compartment where you can't see it.

Many thanks for all these replies. I've got a cap ordered so that will be one thing to eliminate. Strangely, since yesterday morning I've done a couple of trips giving it some boot and the coolant level hasn't moved, and therefore no evidence of any leakage from the tank in the engine bay or around the catch area near the cap. Hmm. I'll have to keep an eye on it every journey and see what happens.

If you are lucky it might just be the cap, but keep an eye on it. When I first got mine it often used to lose a bit of water if I gave it a real ragging. Edit: That was before I fitted the new cap.

Could easily be a slight air lock somewhere in the system. It's a common problem if all the coolant has been drained at some point and refilled. Porsche fill the system by tilting the engine at the factory to avoid trapped air - something you can't do on the road! If your coolant is low, it's important to only top up the coolant with the system 'charged', ie - with between 4-5k rpm. Check the water inlet hose to make sure it are seated properly. Keep a look out for any other traces of coolant residue which might suggest a leaky hose seal.

Thats very useful to know, thanks very much, I'll see how things go the next few days.