Losing Water, but not all the time

[stu]

Driving home last night I got caught in traffic. Not for long, maybe 10 minutes or so. Just long enough for the temperature needle to rise a little, and for the fan to kick in.

Suddenly I noticed steam rising from around the edges of the bonnet and the unmistakeable smell of coolant. Odd, I thought, it's running warm but not overheating. I pulled in to the side of the road and found coolant gushing out from somewhere under the engine. Of course, at this time of year, it's pitch dark and I only had the headlamps of the cars going by to see by so I have no idea where it was coming from.

After a couple of minutes the water stopped gushing out. There was still water in it and I wasn't far from a Halfords so I drove there and bought some coolant, with the low water warning light just coming on. It took somewhat less than a litre to top it up.

It didn't seem to lose any more on the journey home - no traffic, so no fan.

My best guess is that a return hose has split so it's only losing water when the thermostat is open, or when it gets hot sitting in traffic.

This time of year though, I only get to see the car in daylight at the weekend Shame - my girlfriend is away on a course about 30 miles away and I was hoping to visit her tomorrow evening. Not sure if I'll risk it or not.

[dean]

Hi stu

it could be blowing water out of the reservoir, if it does, water will appear to come from the o/s of the engine because that is where the tube is that takes the excess water from the reservoir when the sprung loaded mechanism in the cap opens due to too higher pressure or overfilling. This could be caused by a duff rad cap, which has too weaker spring. The system is pressurised all the time the system is hot, so if you had a hole somewhere it would also leak as the car warms up because that is when the system starts to pressurise.
One more thing, is your temperature gauge lying to you? it could be boiling while the the gauge is under reading,

[jorgy9]

A little tip here, if you discover it *is* the expansion tank cap loosing the water: mine was the same for about 2 years and, except of car loosing water, I discovered in August a cigarette-pack size hole of rust on the suspension strut dome facing it. That area was looking red-ish all this time but had assumed it was just superficial. It was rusted through. Had put new cap a couple of months before! (and it's not loosing any water now). I'd say put a new cap anyway.

cheers
George

[aengus-xmv6]

check when the engine is cold and just starts to get warm - you may find a little fountain from one of the hoses where a pin-hole has developed. This will often self-seal as the water gets hot and then you can't find it.

My 2.0i had that onthe hose from the reservoir down to the bac of the engine block. Made it home from Manchester - SE London and lost about a cup in that distance (rad cap loosened so as not to pressurise the system).

A temporary repair can get you by for a short while, using relevant hose & couplings, but the rest of the hose will eventually disintegrate too, if this is the cause.

regards
Dave

[DrTim]

Might be worth trying some K-seal if nothing else is apparently obviously leaking

I had intermittent water loss about a year ago, mostly when cooling down after driving but also when starting from cold. Water pump changed but indie convinced head gasket gone. K-seal has recitified bubbling in coolant and I wish I'd put some in before having the pump changed now.

Kseal claims to seal leaks up to approx 1mm permamently, and fix 80% head gasket probs permamently.

[jackyboy]

A couple of years ago mine needed to be topped up sometimes once a week, other times it would be fine for 3 months. I reversed the washer on the inside of the filler cap and that was end of problem. Have since replaced the cap just in case but have never need to top it up again.

Make sure you get the right cap because they are different for some models

This post has been edited by jackyboy on November 17, 2007 04:40 pm

[stu]

Thanks for the tips, guys.

This time of year it's difficult to do any diagnosis as I only see the car in daylight at the weekends. This weekend it did start losing water again, again after a short spell in traffic. It doesn't seem to be overheating; the water is coming out as water, the engine's running fine, and I tend to trust the gauge as it normally shows what I would expect, given the conditions.

The water is not coming from the reservoir, but from somewhere under the engine. I really need to get it up on ramps to see where it's coming from, but my ramps are 60 miles away in my mother's garage - I have no off-road space to work down here

Looks like I will have to concede defeat and book it into a garage

[elma]

Is it from the cam belt side?
If so I think you should check/change you're water pump rather quickly.

[dean]

Yep either water pump (most likely) or the alloy moulding that has the return hoses attached to it at the back of the block has a gasket that can give up, when mine went though it was leaking heavily all the time the car was running.

This post has been edited by dean on November 20, 2007 09:35 am