8 replies to this topic

[mgjalopy]

I have a 1963 Classic Mini and the coolant is vanishing, although there are no puddles under the car. It has been back to the garage so many times and they seem unable to locate the problem. If I do not top it up almost every other day it eventually vanishes after a few days. I picked it up from the garage for about the fourth time on Thursday night and driving home from work on the following Monday the valves started knocking, the guage went into the red and the coolant had almost boiled away. It also suffers from pre-ignition, although I do not know if this is associated. When I top up the radiator every other day I can actually see the water level and it takes very little water, but this constant topping up seems to help the problem for some reason, whereas not doing it results in the coolant just mysteriously vanishing. I believe the garage has changed various thermostats and pumps but obviously there is something else going on.

It had a complete engine rebuild after a piston went through the engine, and it seems to have suffered from this problem every since.

Can anyone offer any advice please?

Thanks.

[JonnyBMX]

i do know if the coolant system is not pressurised the water will boil, pressurised water boils at over 100 degrees c this is why it is pressurised, could it be boiling out and going out through the overflor pipe? maybe all over your nearside wheel?

it obviously has to be going somewhere

[Mad Max]

Also check you heater is leaking. I've know a couple to start leaking when it gets hot. The water could be dripping inside your footwells.

[CMXCVIII]

I rather suspect that if the coolant loss is not showing up as puddles underneath the car, it's leaking internally into the engine and then out of the exhaust pipe.

How did the "piston go through the engine"? What did the garage do to rebuild it and what have they done since then to look for the disappearing coolant?

[SA MINI]

If it is boiling away. Make sure your rad is full go for a drive or get it running so it's really hot. Then turn it of. If there is a leak in the rad or pipes you will see some steam somewhere or a hissing sound of the boiling water escaping / evaporating.
Is there any sign of water on your subframe under the rad ? Also what is your temperature guage doing whilst driving ?

Edited by SA MINI, 21 August 2012 - 10:56 AM.

[BritishRacingGreen]

Any smoke (steam) coming out of your exhaust? This can be a sign that the head gasket has gone and water is getting from the water jacket into the cylinder and is burning off that way.

Your garage 'should' have picked that up, but it's probably worth a test to see if there are combustion gasses in the water.

[mgjalopy]

Thanks to all for responding. In answer to your questions :

>there are no external signs of any water leaking out and no water inside the car
>the piston went through the engine when the head gasket went. I believe they cannabalized another engine to make one good
one. Since then they have replaced the water pump, thermostat, valves, internal heater and put the rad under pressure to check
for leaks. Sorry - I am not a mechanic so cannot be more technical!
>not seen any steam from the exhaust and cannot hear any hissing noises, etc. Usually the temperature guage sits about halfway
but after about a day it starts to creep up and eventually goes into the red and the valves start knocking.

I checked the coolant this morning and it was down about half a litre. This is since Monday evening when it virtually boiled dry and I had to fill it up. I could see the guage already starting to climb when I drove home last evening, and the heater inside the car was only blowing cold air by the time I got home - even though the temperature guage was heading into the red.

I know the car is old but I have had it from new and it has been looked after by the same garage since 1986 so they know it well. it is good old fashioned basic mechanics and not technical wizardry like most modern cars, so it must be possible to track this down. I would hate to have to get rid of it or spend the rest of my days topping up the water before every journey!

[Spud_133]

Sounds a lot like a head gasket failure to me!

[Ethel]

You are only filling it to the level of the indicator bar under the radiator cap? You could rig up a catch tank for the radiator overflow to see if it's blowing past the cap. As the heater valve is the highest point it could leak only steam, making it harder to spot.