Have I got a water leak?

[Anonymous]

Ok guys, here is one for you............

Bit worried about this to be honest. I left work and theg temperature gauge went up to normal operating temperature a lot quicker than usual. It was a little chilly, so I opened up the heater and upped the temp on that, but all I got was cold air. And this happened for about 10 mins. Temp gauge looking normal, freezing air coming through the vents. I thought this a bit weird (it had done the same thing a couple of days ago too), but I thought mayube switching on the air con might do something. I got no warm air, but the temp gauge then shot up to about three quaters and was still rising before I turned the AC off and then backed off the joice pedal a bit. The gauge went back to normal, but then I tried the same thing again and it did it again! So, I backed off and turned it off and slowed right down to about 55-60mph (was the A14, a fast road normally).

After another couple of minutes, the gauge settled down and a started to get heat through the vents. But the whole episode has made me a little worried, especially as it had done it before, sporadically over time, but not as bad as this.

I got home and let the car cool and have now checked both oil and water. Oil was fine, but there was hardly a drop in the header tank. Literally dreggs in the bottom. So I have filled that, but it has got me thinking. A few questions to you all:

1) Have I got a leak somewhere in the cooling system for the water to go down that much over time. Admittedly, it has been a little while since I have checked the water, but its never been this low.

2) It has been going down over time as I have just said, but not that bad. Just takes a small top up every now and then. But there is one proviso. If Grant is reading this, can you shed any light on this? The water levels have only started to drop since Grant gutted the pre-cats for me. Its was perfectly fine before that and I didn't need to touch it in anyway.

3) Do I have an airlock now? I know with my Mk1's, which were prone to air locks in the water system, the gauge did similar things to what mine has done today. Is there anything I can do about this? Are airlocks easy to remove on the Mk3 (dead easy on the Mk1). Also, IS it an airlock? Have I now caused any damage to anything by having "hot spots" in the block or anything? Or is it that the lock is near the heater, hence the heater didn't work right?

4) Where IS the water temp sensor? Would like to know cos then I can get a better idea of what might be causing this.

Sorry for the long post, but I am little worried about my baby. She has given sterling service without a murmur from her since I have had her and now, especially with the delicate engine we all know they have, I want to be sure I have not got a major problem or that I have caused some expensive and irrepairable damage.

Cheers guys. I am sure some of you will come up with some perfectly goo reasons for what is happening and why...........

[Anonymous]

In previous cars anything like you describe is either a blocked or empty cooling system. If you don't get any heat coming out of the heater then it's not getting any hot water. And if your gauge comes up quick and goes through the roof, that sounds like a blockage or air lock.
Gordy

[kanujunkie]

so where's the water gone then!

it has to be a leak,

Put a hose pipe running gently in the resovoir. fill it up and check under car for leaks. If none then start the engine and check again. Water doesn't just evaporate in an instant it has to go somewhere. Just don't run it for too long.

[Anonymous]

They can have vapour leaks - I only noticed I had a coolant leak on my mk1 when I got under the front of it to replace some suspension (I accidentally "modified" the lower arm and front tie rod against a kerb because some geetle (see rogers profanisaurus) decided to pull out in front of me   s:evil: :evil: s:evil:  ) - I noticed that where the steel coolant pipes ended and flexible rubber hoses were attached one was weeping very slightly, where the clamp on it had started to fail.

It wasn't enough to cause a wet spot on the floor, but made a slight wet patch on the bit of body work it was against. I just slipped a jubilee clip over it and the problem was solved.

Any way - I digress - it could just be a very small leak like this. It does sound that you have a coolant leak/blockage/airlock somewhere maybe!?!

[Anonymous]

Still a little confusing this guys. I am like Stu, I want to know where the water is actually going. I am guessing that the lack of heat in the heater was an air lock that had been psuhed through cos the header tank was so low on coolant. I tried her this morning after filling her up and there was no problems at all, so hopefully keeping her topped up should not cause problems short term. But it still doesn't explain the oss of coolant. I can only imagine that it is VERY slow loss, but a loss all the same. I can't really check for leaks cos 1) its wet all the time at the moment, 2) don't have the facilities to bring her indoors and have a good rummage around and 3) because of that, its outside and nearly always dark when I set out from work and when I return in the evening, so can't see anything anyway.......

Going to have a look this weekend if the weather is Ok. But would be interested to know if anyone else has any more views on this................

[Anonymous]

I got home and let the car cool and have now checked both oil and water. Oil was fine, but there was hardly a drop in the header tank. Literally dreggs in the bottom. So I have filled that, but it has got me thinking. A few questions to you all:

1) Have I got a leak somewhere in the cooling system for the water to go down that much over time. Admittedly, it has been a little while since I have checked the water, but its never been this low.

I'd say you must have a cooling system leak.  The water must be leaking out either to the oil, bores or to outside.  If your oil level hasn't gone up then the water can't be going there.   The wierd stuff with the heater is symptomatic of air and not enough water in the system.  

2) It has been going down over time as I have just said, but not that bad. Just takes a small top up every now and then. But there is one proviso. If Grant is reading this, can you shed any light on this? The water levels have only started to drop since Grant gutted the pre-cats for me. Its was perfectly fine before that and I didn't need to touch it in anyway.

If its been going down over time you must have had a small leak that's now larger.  Others will confirm or not, but I have not added a drop of coolant to MR2, Mondeo or Polo in a total of 170k miles.  

Other points - I reckon the pre-cat exercise cannot possibly be connected, except that you might have somehow agoragated some existing small leak.  If it were my car I would begin with radiator and all hoses with the engine running.

Oh, and keep it topped up with proper coolant mixture so it doesn't corrode or freeze!
Good luck!
Andy