I have a low coolant alarm - phew!

Well, this week my coolant alarm has proved its worth.:yesnod:

Suddenly, the car has decided to lose coolant invisibly. For months, the level has hardly moved and I have probably become a bit lax in checking the level.

Earlier this week, Sheila came in and said 'the blue light's started flashing!'

Out I go and 'yep' the coolant is at the minimum level. After the engine had cooled, I carefully removed the expansion cap and refilled to the max level. 500mls added. ( Never remove the cap when the engine and coolant are still up to running temp. The sudden drop in pressure can allow the coolant in the head to boil and leave your head with no coolant in it.)

Came back in the following day, back on the minimum level.:confused: That's 500 ml gone in a day!

I checked all the usual suspects - no pipework leaks, no inlet manifold leak, changed the expansion cap, no cross contamination, no external HG leaks, No radiator/ cap leaks, no steam from the exhaust, no pink staining anywhere. :dunno:

The next day, back on the minimum level:rolleyes2:

Investigations are ongoing. I'll update the thread if and when I discover the problem.:yesnod:

This has brought home to me the vital importance of fitting a low coolant alarm. Without it, there's no doubt we'd soon have been driving around with next to no coolant in.:shake:

Hi David, that is very strange, where is the coolant going??? i had a very simmilar problem on a company 2.3l Ford Granada many years ago, it was eventually found (after the engine blew a core plug) that the head was cracked between an exhaust valve and a waterway causing the water system to become over pressurised and blowing the coolant out of the header tank cap. perhaps a call to Russell Walsh of MG Rover solutions may throw some light on the problem, because he has seen so many head failures for whatever reason. i thing everyone will be interested in the outcome. Kind regards Bryan

Bryan Young;13287 wrote: Hi David, that is very strange, where is the coolant going??? i had a very simmilar problem on a company 2.3l Ford Granada many years ago, it was eventually found (after the engine blew a core plug) that the head was cracked between an exhaust valve and a waterway causing the water system to become over pressurised and blowing the coolant out of the header tank cap. perhaps a call to Russell Walsh of MG Rover solutions may throw some light on the problem, because he has seen so many head failures for whatever reason. i thing everyone will be interested in the outcome. Kind regards Bryan

That's the million dollar question! Russell did the HG on it about 18 moths ago, and since then it's been fine.:dunno:

The system is not over-pressuring, as far as I know.
I have found some pink staining around the heater valve behind the centre console. I'm going to replace it and take it from there.

Have you replaced the rad at all David? Meg's last leak after HG replacement by Russell turned out to be a very weepy rad! It was boiling off before dripping so wasn't noticeable.. but she let water out in a similar fashion to yours.

AdamElphick;13309 wrote: Have you replaced the rad at all David? Meg's last leak after HG replacement by Russell turned out to be a very weepy rad! It was boiling off before dripping so wasn't noticeable.. but she let water out in a similar fashion to yours.

I changed the rad to an ally core one last year, but again I can't see any evidence at the rad or the famous bleed screw.:dunno:

Checked under the carpets?

AdamElphick;13311 wrote: Checked under the carpets?

Yup:yesnod:

I installed one of the first B&G low coolant kits. I never conected the warning light as I did not want to put extra holes in the centre consol and even at racing speed with helmet the alarm can be heard. Within a week of fitting it had paid for it's self, I had been doing a lot of stop start motoring that morning, about lunch time I started the car and the beeper sounded checked the water level..empty. Filled it up then went on the 15km drive to the workshop, just as I arrived it started to beep, the temp gauge all this time showing normal. Checked the water level, none. Left it at the workshop and waited for the bad news, phone call the next morning come and pick up car. As it had only been there for a few hours before they closed knew it wasnt a HGF. Water pump less than 20000km, 12 months old had failed.

AndrewR;13318 wrote: I installed one of the first B&G low coolant kits. I never conected the warning light as I did not want to put extra holes in the centre consol and even at racing speed with helmet the alarm can be heard. Within a week of fitting it had paid for it's self, I had been doing a lot of stop start motoring that morning, about lunch time I started the car and the beeper sounded checked the water level..empty. Filled it up then went on the 15km drive to the workshop, just as I arrived it started to beep, the temp gauge all this time showing normal. Checked the water level, none. Left it at the workshop and waited for the bad news, phone call the next morning come and pick up car. As it had only been there for a few hours before they closed knew it wasnt a HGF. Water pump less than 20000km, 12 months old had failed.

Yeah, this is the problem of course. Convoluted and hidden pipework and a temp gauge that is so damped that damage is done before it shows a significant rise.:whistle:

I've just remembered that when my coolant was disappearing, my water pump had a leak. new water pump and radiator (to be on the safe side) and I don't think I've lost any since.

Hi David ~ Me again, one of the HGF failures sorted by the MG Owners Club was as the result of the impellor coming off the pump inside allowing the water to boil off, i beleive that Moto-Build do a better water pump with a brass impellor but they are around £60, whereas the replacement X part one is £30. Have you checked the underfloor pipes as theese are bad for rusting through and weeping out, the stainless ones at £60 are good value and seems sensible to replace them whilst the system is drained. Regards Bryan

Bryan Young;13344 wrote: Hi David ~ Me again, one of the HGF failures sorted by the MG Owners Club was as the result of the impellor coming off the pump inside allowing the water to boil off, i beleive that Moto-Build do a better water pump with a brass impellor but they are around £60, whereas the replacement X part one is £30. Have you checked the underfloor pipes as theese are bad for rusting through and weeping out, the stainless ones at £60 are good value and seems sensible to replace them whilst the system is drained. Regards Bryan

Hi Bryan,

She had a new water pump 18 months ago and there is definitely plenty of circulation evident. I also replaced the u/floor pipes with ss just after we got the car.
Thanks for all the ideas, but you can see I think, why I am at a loss for ideas.

I have now replaced the heater control valve and the old one is heavily-stained pink. There was, however, no moisture under its position, but I'm hoping!:dunno: It'll take a few days for the coolant to sort itself out after the refill, so I'll keep you all informed.