Coolant loss and a couple of other things

I've had my '98 996 a few months now and covered just over 2k miles so far. Last month I had started a thread due to the CEL light coming on and the engine 'hunting' but a clean of the MAF sensor seams to have sorted it. However, one problem that seems more permenant is the coolant level - it had sank about 10-15mm below the min and I thought it may just need a top up (which I did) but it's sank back down again. I couldn't see any obvious sign of leakage below the tank but one thing I should mention is it seems to have found a 'level' (ie. it doesn't seem to go below a certain mark). Obviously a big fear would be a head gasket - does the fact it finds a natural level go against that theory? I thought I'd best keep an eye on oil levels too but I find the instrument panel all but useless as, depending on where the car's sitting, it can vary from 1 bar from the top to 2 bars from the bottom! Short of finding a perfectly level surface is the dipstick the best option? Another thing that seems to have developed is a creaking noise (I can hear it at low speeds though pressumably it's just masked by engine noise at higher speeds). It's like a creaking door! One thing the PPI mentioned was a noisey wheel bearing - is this a likely contender or is it more likely shock spring related?

Well if it had a leak from anywhere (apart from the header tank somewhere higher than the level it finds) or was using coolant via a cracked cylinder head or cracked liner the level would continue to drop until the tank was empty. So either a leak from the tank itself above the stabilized level, or possibly loss through a faulty pressure relief valve (on top of the tank) or faulty cap (quite common) The creaking could be a drop link or coffin arm....mine was a drop link, noticeable most at very low speeds over bumps.

The header tanks can develop cracks or pin-holes over time (fatigue). This would tie in with water level limit. You could fill the expansion tank back up to maximum and tape a piece of kitchen paper around the tank. Go for a spirited drive and see which bit is wet (if at all). If it is wet you need a new tank.

It might also be the expansion tank cap, which is a common problem. If the part number ends in 00, cjange it for a new one. The creak could be one of the lower wishbones (coffin arms), which sound like old bed springs squeaking. If you don't measure it on a level surface you will have the same problem with the dip stick readings.....

After the usual culprits were changed, the creaking on my car was from worn anti roll bar bushes.

I think mathamb mentioned that. :wink:

Thanks for the help guys, will look into those. The other thing I forgot to mention was the air-conditioning - the condensors had just been replaced last year (and will have had very little use) but when I turn the AC on I get a noise that can only be described as 'like twinkling crystals' :lol: yet the air isn't even close to cold. I'm thinking most of these things wouldn't been present at the PPI and I'm questioning how thorough they were!

Were they refilled? If they were refilled, did they also recieve the correct refrigerant oil (195 ml)? Were they pressure/leak tested? If the system has vented to the atmosphere you will need a new reciever/dyrer too.

No harm in emphasising the point! :wink:

Let me emphasise, mathamb mentioned that

Not too sure on those details GT4, just have the invoices but will just again to see if there's more info. Checked the creaking again but pushing down the nose with my hand - very audible even at that and seems slightly louder on the passengers side but also present when I push the drivers side.

On the subject of creaking, could be suspension bushings. These are "wear and tear" items. Very common to creak on the rear, but they are fitted all round.