Total coolant loss

[alexinapot]

Bit of a back story first. Just before Christmas we were approaching South Mimms Services on the M25 (about 12 miles from home) when the overheating alarm went off. We pulled into the services and had a coffee for half hour and then checked. Temperature had dropped, the coolant level was ok but we decided to return home. Temperature was normal on the return journey. Car was due for service plus cambelt/water pump change in a couple of days so asked the garage to check. They found nothing nor did they find a fault code on the OBD. Car has been fine ever since though we've only been using it locally.

 

Fast forward to today when the 'Check coolant level' warning came on as soon as I started the car. On checking the coolant tank was completely empty. There was no liquid beneath the car. Last time we used it was last Thursday when there were no warning lights, temperature was normal and the car drove perfectly normally.

 

My thoughts are that if the coolant isn't coming out it's going inside the engine somehow. Head gasket failure? Have had this many years ago and there was a very noticeable effect on performance. Nothing like that this time. I'll have to take it to the garage but will it get there? My plan at the moment is to refill the coolant tank and run the engine to see if the level is holding. If it is I'll go round the block a couple of times and recheck. If it still holds I'll drive to the garage - about a mile.

 

Interested in anyone else's ideas as to what might be the problem, Has anyone had anything like this happen? Does my plan for getting to the garage sound feasible or should I bite the bullet and pay for it to be trailered? 

 

All ideas, comments and opinions welcome - I'm stumped.

 

JC

 

 

 

 

 

 

[Prezafab]

Holed radiator ?

[Kenny R]

If it has had a new cam belt and water pump, the coolant would have been drained.

It could just be the coolant finding it’s level after being re filled and any air bubbles released. I would fill to correct level and monitor closely for a few days.

Edited 9 January by Kenny R

[Austin 7]

Hi

 

You could probably drive a mile in cold weather from a cold start with no coolant at all, though I wouldn't recommend it !

 

I suspect you still have most of your coolant in the system, try squeezing the large radiator hoses - the "feel" will tell you if there is air or coolant inside.  If still mostly full I suggest as above that you top up with the correct stuff and then use the car but keep a frequent eye on the expansion tank level and the temperature gauge.

 

Coolant often contains a dye to help with leak tracing, can you see any pink residue around hose joints etc ?  I think gasket failure is unlikely, and you would detect a misfire/lack of performance.

 

When the original alarm went off, what was the temperature gauge showing (if you can remember) ?  It's possible that the thermostat is not opening fully and restricting the maximum flow to the radiator. Maximum flow is only needed when the thermal load is high e.g. motorway driving.  One failure mechanism of a wax capsule thermostat is that it loses some of its wax and then doesn't open fully.  This probably won't trigger any fault codes. Clearly something triggered the original overheat alarm and it would be good to get to the bottom of that even if things seem OK now.

 

If you ever find yourself in an overheat situation where you can't pull over promptly, it's a good idea to put the heater on maximum and use full fan assistance to take the water temperature down until you can stop safely.

[alexinapot]

Prezafab  -  hadn't thought of this. Have now checked and no damage that I can see. Also would have expected to see coolant on the ground under the car but all is dry.

 

Kenny R -  my first thought was that while this seemed feasible it had taken a long time to show up as the work had been carried out on 17 November. However looking at mileage we've only done 240 mIles so not long in distance terms at all. I've VAG coolant arriving later today so will take it from there

 

Austin 7 - top hose feels quite soft. Probably not a good sign. No indication of leaks anywhere that I can see. I remember the old heater and fan trick from running many BMC cars in the 70s!

 

Thank you all for your input. I'll update as and when

[g7eor]

Although on a different engine my cambelt/water pump was changed recently. The garage  told me to run the engine up to temp and then allow to cool down , then top up with water as it would be needed. the garage had put sufficient antifreeze to allow for a small amount of dilution

[alexinapot]

g7eor - my garage said nothing like this but Googling 'coolant loss after water pump replacement' brings up a host of hits.  Looks like an air lock is possible so will check this out too when the coolant I've ordered arrives

 

Thanks

[Paul52]

"If you ever find yourself in an overheat situation where you can't pull over promptly, it's a good idea to put the heater on maximum and use full fan assistance to take the water temperature down until you can stop safely". (Austin 7). Brings back memories and I know it works as years ago I had to drive my ancient Renault 16 back to Hampshire from the West Country with the heating on full, fan spinning like a Dervish and frequent stops to allow the engine to cool enough to refill the leaking radiator. And all this on what turned out to be the hottest day of the year! But once the radiator was replaced the car was fine and it saved me a fortune on recovery costs.