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Discussion Starter · #1 ·
Happily tootling along to work this morning (as happy as you CAN be when going to work!), when the message centre lights up, "Engine Overheat!". A quick glance at the temperature gauge confirms it, it's at maximum with the little red warning light glaring at me (MG ZT 190 by the way). "Oh Poo!" I'm thinking, and as I'm on the Expressway doing 60mph with nowhere to stop I'm scouring for a safe haven to pull over. Hard shoulder is 500yds down the road but, as I glance at the gauge again, the light goes out and the needle steadily resets to normal. "Very strange" I thought, maybe an electrical glitch?
Got to work with no more drama but as the engine was hot I couldn't check the water 'til it had cooled. I checked under the bonnet but couldn't see any obvious sign of water leakage but there was an the ominous odour you get when water is leaking from somewhere.
Finally got to check at lunchtime, expansion tank was empty! Oops. Now I usually check this about every month and it's NEVER needed a top-up, although admittedly, I haven't checked it since just before Easter, even then it was OK. Topped-up and checked again for leaks but couldn't see anything obvious. There was a water drip from the undertray but when I checked the water was clear and odourless, so I just put it down to excess rainwater from the morning drive. ran the engine for 10-15mins then checked water level again, which was fine.
Me being paranoid I checked water again before I left work, it had dropped to minimum. Topped it again and looked to see if any evidence of leakage under the car, the floor was wet but as it had rained most of the day it was hard to tell if there was anything actually from the car.
My eyes were fixed to the temperature gauge all the way home, it moved from cold to "normal" operating temperature in less than 5mins and a couple of miles driving. I thought it was strange (is that a bit quick?) as I've never seen it get to temperature that quickly before, ever! Stayed steady at normal all the way home and had no problems. Just been out to check the water again now it's cooled and the expansion tank is empty again! I can't see any evidence of a leak though, as I said, the floor is already wet from the rain so hard to tell. I checked when I pulled up while the engine was running and hot to see if there was steam coming from anywhere but nothing. Fearing the worst I've checked the oil filler cap for mayo but it's clean, apart from dirty oil!

So I'm after a few pointers as to what the problem could be. Seems to me there's obviously some sort of leak but will I have to remove the undertray to have a good look? Can't see an awful lot from the top and, as I said, there's no obvious sign of a leak. :confused:
 

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Does not sound good! Check your oil dipstick for mayo too. Also if your water goes down a lot it may need bleeding as well as just topping up...dunno how to do this on your car but sure someone here will know.

5mins is OK i think...modern cars are designed to heat up as quick as possible. Though it should be the samish every time i reckon.

Also could be your expansion tank cap...I've heard the valve on the top can break - leaking fliud everywhere. Surely you'd see the traces left by the antifreeze though?

good luck
Rob

ps sounds like you need some good weather too!
 

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Heat up time is about right for the KV6. Mine does it even quicker when the ambient temp is high. You need to check:

expansion cap
water pump
coolant pipes and clips (clips are known for loosing tension so replace with jubilees)
radiator
thermostat-sited in the V and can fail leading to loss of coolant

Look for orange staining from the OAT coolant to help find source of the leak. Get a pressure test done if needed.

Advise do not drive until you have found leak. If you do drive it then you will likely trash the hg/engine meaning big £££ bills.

Good luck

Mike
 

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On an older 4 pot K-series, I'd be checking for HGF, but the V6 doesn't really suffer from this.

Not really sure - I'd check for leaks first. What kind of mileage has your car done?
 

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Discussion Starter · #6 ·
Thanx for all the advice but up to now I've found no evidence of any leak, no sign of coolant spillage anywhere. The tank cap seems OK, when I loosen it off there's a distinct hissing of pressure release and no sign of leakage from there anyway.

Checked the water level before I left for work this morning and, surprisingly, it was fine. Drove to work with no fuss then checked the water level again at lunchtime. Empty again, so topped up, ran engine whilst inspecting around for leakage (still couldn't find one), then left a huge sheet of board under the car for the rest of the day to give me an easier indication of anything dripping. Checked again before I left work, board was bone-dry with no sign of anything having dripped onto it, and water level was fine. Got home and checked for any sign of leaks while engine was hot and running (nothing), then left it a couple of hours before checking water again, expecting to need a top-up. Water level was fine, didn't need a drop. So now it's a mystery. Began to think it wasn't actually leaking whilst idle but managing to lose water while running, but the fact it didn't need a further top-up after the drive home has now got me baffled.
 

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my pug 406 did the same thing, no signs of leaks anywhere but it emptied the expansion tank within 10 min of driving, had to stop for an hour to let it cool down enought to drive 3 miles home then the HG went and i sold it to a guy who could fix it and i bought my R25....i keep an eye on my levels and do checks weekly!
 

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Assuming you have the engine undertray then you are unlikely to see any drips onto the floor. If you want to test that way then best remove the undertray. As before if you are losing that much coolant then each time you drive the car you risk more damage to the engine.

Also remove the plastic top engine cover-that wil lgive aq better view of the thermostat.

Regards

Mike
 

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Discussion Starter · #9 ·
Latest on the water mystery:

After having to top up the last couple of days after travelling, I think I mentioned that after getting home from work last night the car didn't need any water, level was fine. Checked before leaving for work this morning, again OK, then another check at lunchtime, before leaving work, and again this evening. Each time the level is fine. Bloody baffling!

I'm just wondering now whether, as I hadn't checked the water for a while, I'd actually "lost" water in normal usage and it had just got to the point this week where it was telling me "fill me or else", and that every time I topped up I was just basically re-filling the system to the point where it's now where it should be. Probably completely wrong but I've no explanation as to why the water loss has suddenly stopped. As I've said there's no sign of any leak, no mayo on oil filler cap or dipstick, and the water in the tank looks like, well... water, no hint of any oil in it. My concern is the fact that the water looks just that, water. No colour in it, surely with the anti-freeze it should have at least a hue of red/orange?

Anyway, it's due for a service anytime now so I'll get them to have a look, 'til then I'll just keep my eye on it.
 

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Discussion Starter · #11 ·
Gonna check out the thermostat over the weekend, just in case. I need to have a proper look around for leaks just so I know, or not. I'm kinda hoping that there IS a simple leak somewhere that'd explain the problem, and not something that's building into a more serious fix.

At the moment I'm just driving with one eye on the temperature gauge!
 

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There's no doubt this car has a slow leak somewhere and finally emptied the coolant. The fact the gauge failed to register after the first warning probably meant there was no liquid at all, so the sensor couldn't work. This is very bad and could lead to engine meltdown if it happens again. It's possible a faulty cap or leaking pipe or thermostat has righted itself for now, with the new water , but the whole thing needs thorough investigation.
 

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Discussion Starter · #13 ·
I don't think I actually ran the cooling system dry, I believe the whole system has a capacity of 7 litres or so, over the last few days I've probably topped up about a litre and a half, certainly no more than 2 litres. OK, that is a fair bit but it wasn't completely drained. Just a mystery as to where it went. Raining again at the mo so can't get to check thermostat or hoses. Oh for a bit of sun!
 

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:D Just a point on this one. When you were refilling with "water" did you also add anti-freeze ? I say this cos diluted coolant is going to boil quicker with no anti-freeze in it and I'm guessing blow through the cap too easier ?
 
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