Morris Minor Owners Club

Hello I have a 1098 engine 1966. the car seems to get very hot and overheat. All the hoses are good - no leaks. The heater was refurbished, works well no leaks. The thermostat at 82 is new and tested ok. The rad has been taken off and flushed. When warm appears warm all over. I have fitted a temperature gauge, its working and giving me warning! When I stop I do need to top up the radiator? What is wrong please?
Ann Malcolm

Ps The cylinders all have good even pressure and the head seems fine. i also have an oil pressure gauge reading stable. Sorry thought I should add this bit!

First thing make sure the fan belt isn’t slipping

What exactly is it that makes you think it is overheating?
You say the radiator needs topping up but is the water level really low? Or has it simply dropped a little like this type of cooling system always does because of expansion. Modern cars have a "no loss" system but a Morris Minor does not and expansion means that you'll always lose a little water if you keep filling it right up. The thing to do is to let it find its own level and don't expect to keep the water level right at the top of the radiator.

It is normal for an engine to get "very hot" when running on a hot day. There MAY be nothing wrong with it at all

If your temp gauge is accurate and the reading is staying around the 82 degree mark then there is very little wrong with the engine/cooling system.
So long as the radiator core is covered with coolant then all will be well and will not require regular topping up.

Ann, it may help if you give us the symptoms of your overheating. Is it actually boiling over or...?

I'm not convinced there's a problem at the moment.

How do you know the temp gauge is correct?
Is it an electrical one with matched Gauge and Sensor, or is it a mechanical one with the Bourdon Tube attached to the gauge?
It's easy to but gauges and sensors separately and they give false readings.
What makes you think it's overheating, is there any leakage anywhere?
Are you leaving a sufficient expansion cap in the radiator?
The book says 1/2" gap below the bottom of the Radiator Cap seat, personally I aim to have 1/2" to 1" gap.

If the level is dropping and the water is escaping via the overflow pipe, then it could just be the Radiator Cap needs replacing...

When I stop I do need to top up the radiator?

Is that a Question or a Statement? If you are just stopping because the gauge is reading high, how are you safely removing the Cap?
If it's not got a lot of pressure behind it, then the problem is the cap not fitting properly....

Measure the actual temperature of the coolant when it is circulating into the radiator. Report back.

Thank you all for your comments. The gauge is accurate with an electrical connection from the top of the block. The gauge is used to give a warning but yes the rad does boil over. topped up to close to the top as suggested, the cap is a 4lb one and working. Previously we had a 7lb one but this has not cured the problem. the belt is tight. I am planning on doubling the fan to a four blade with additional one bolted on?
hope this helps. Thank you Ann

I think you need to check the water pump, make sure the impeller hasn't become detached. Minors are very overcooled so I doubt the extra fan blade would make much difference.

Don't top up to the top of the rad, just top up to about 1 inch above the radiator core, the room left above the water acts as the expansion tank. This allows for the expansion of the coolant.

topped up to close to the top as suggested,

NO, I said an inch gap.

I am planning on doubling the fan to a four blade with additional one bolted on?

NO, don't do that, the extra blade was for Equatorial temperatures, not to mask a fault which you clearly have.....

the belt is tight.

It shouldn't be 'tight' ... the usual check is to move the longest section of the belt, between bottom pulley and dynamo 'in and out' (for want of a better term) and there should be about 1" lateral movement.

Fix the fault, don't try to compensate for it.

Ann, from what you have said, the rad, thermostat and hoses are OK and it seems that the fan is turning. Assuming the ignition timing and carb settings have not been fiddled with recently, and that this problem arose 'out-of-the-blue', it could well be the water pump or sediment in the engine block.
You could try flushing out the engine block.
To see if the pump is working, remove the rad cap and then get the engine to operating temperature so that the thermostat opens and then see if there is movement of water across the top of the rad. If not, take the pump out to check its condition.