Blue Liquid dripping out of heater

[PWLMORRISMINOR]

Dear All,

I recently purchased a 1960 minor convertible, I am most definitely a novice, so I would greatly appreciate any advice.

I turned on the heater for the first time just before Christmas. I blue liquid which I believe is coolant started dripping from the heater inside the car's interior. I have tried to switch off the the heater, however this is not stopping the dripping, which is signifiant.

If I turn off the ignition, the dripping stops.

All thoughts gratefully received.

Patrick

[myoldjalopy]

Do you mean when you switch the engine off the dripping stops? If so, the coolant stops being pumped around when the engine is not running and the leak may then stop due to a drop in pressure. Check the heater hoses first.

[geoberni]

Well
I assume you mean it stops when you stop the engine running, not that you're sat in the car simply turning the ING switch on and off without starting it....

Just operating the heater knob/lever/tap (depending on type) will simply interrupt the circuit of flow for the coolant in the system, so the heater doesn't work.
But if you have a hole to allow the liquid to escape to the big outside world, then it will find it, wherever it is.
It sounds like you've either got a old/worn hose problem or the heater matrix has rusted through, it is only a miniature radiator after all.

[PWLMORRISMINOR]

Many thanks for your kind and helpful responses.

What has puzzled me, is if there is a leak in the heater circuit, then wouldn't switching off the heater isolate the leak ?

Also, in terms of topping up the coolant, are there any you would recommend or avoid ?

thanks again

Patrick

[philthehill]

The leak can be fed from the return side of the heater even though the heater valve is closed. The heater valve does not isolate the heater coolant completely only the circulation.

[geoberni]

What has puzzled me, is if there is a leak in the heater circuit, then wouldn't switching off the heater isolate the leak ?

I explained that above, but perhaps not clearly enough.
Do you have hot water radiators where you live?
Hot water circulates through the system and the heat emits from the radiator.
If you turn the radiator off at the Manual Control Valve, you have closed off the circuit and the heat in the radiator dissipates because the water is not being replace with freshly heated water. It doesn't matter if the MCV is in the feed from the system pump or the return to it, the circuit of Boiler, Pump, Radiator, back to Boiler has been broken by closing the valve.
But that 'stagnant' or stationary water is still under the pressure of the system pump.
If you were to now open the bleed valve, you would still get water squirt out over the floor because it's fed from the pressure in the system.
The only way not to have water escape from the Bleed Valve would be to also close the Lockshield at the other end of the Radiator.

Radiator.jpg (41.73 KiB) Viewed 957 times

Also, in terms of topping up the coolant, are there any you would recommend or avoid ?

Now you're asking....
There are so many types these days, specifically aimed at newer engines and having different corrosion inhibitors.

P-HOAT (Phosphated HOAT) – Phosphates and organic acids – Blue or pink

IAT (Inorganic Additive Technology) – Silicates – Green

OAT (Organic Acid Technology) – Organic Acids – Orange

HOAT (Hybrid OAT, Phosphate-free) – NAP-free – Turquoise

HOAT (Hybrid OAT) – Silicates and organic acids – Yellow

Si-OAT (Silicated HOAT) – Silicates and organic acids – Purple



You will find differing opinions on line, but steer clear of the last 4 colours, as they are definitely for the modern stuff and are not designed for systems with lots of ferrous components, like simple cast iron engine blocks.

Best option is to stick with traditional blue or one that says it's for Classic Vehicles.

[Jim McCrae]

Your leak could be a number of things: perished hoses, corroded heater matric etc. but start with the simplest first. Look under the right hand side of the dash and check that the jubilee clips holding the heater hoses onto the heater are tight. Two minutes with a screwdriver might fix the problem.
Good luck.

[mogbob]

Patrick Good advice from the guys. Sort the source of the leak out first and after rectification ... refill with antifreeze later.
You can flush through the heater matrix separately if you wish , simply using the inlet and outlet pipes but flushing the whole cooling system would be my suggestion. Check the condition of the top and bottom hoses
to the radiator now , before draining the system. If the rubber is perished / perishing a bigger leak might be in waiting.
Inside the car protect underneath the heater with old towels. So plan is ...check jubilee clips on the inlet and outlet heater hoses, are the supply pipes sound ? If yes , then the heater matrix may be damaged and the heater will have to come out for repairs to be effected. With a sound water tight cooling / heating system you can flush through with clean water from the hose and the refill with antifrezee.
Bob

[myoldjalopy]

One other point - if the heater hoses have, indeed, perished, check all the other coolant hoses, as they may be ready for replacement as well!

[mowogg]

Just to note the whole heater can be bypassed and the car can then be used while you repair the fault at your leisure. Not so good for this time of year.

To do this connect the two hoses together under the dashboard. I ran one like this all summer once.