Morris Minor Owners Club

I am new to mechanics and new to Moggies. My 1967 has started to run hot. The after market temperature gauge is all the way to the top and does not come back down, and after driving a couple of miles i get the start of steam. When i stop i lose coolant - a significant amount.

My assumption is that the water pump has failed. As i said, Iam new to mechanics - is there an easy way to check for failure before ordering parts from England (I am in USA)

Please don’t make assumptions - they are often incorrect.

Apart from a failed/failing water pump, the problem could be caused by any one, or more, of several possible faults.

Failed cylinder head gasket, failed thermostat, blocked radiator (internal or external), cracked cylinder head, blocked waterways within the engine. May be others, like fan belt, incorrectly installed fan, over-filled radiator.

A compression test/check is advisable. Simple observations of coolant flow, as the temperature rises above the thermostat, might be informative.

Just do not assume until checked out. You may be simply changing serviceable items and causing further damage to the engine.

Just a supporting comment from me for what's already been said by Oliver.

All too often we see people jump in with both feet instead of following logical fault diagnosis.

It's very easy for a failed Thermostat to cause these symptoms and it's perhaps the most likely.
Minors have a bit of a reputation for the Housing being a bit of a pig to remove after many years in place, so the first thing you could do is start the car and as the temp starts to rise, carefully remove the Rad Cap before it pressurises too much.
Then as it gets hotter, look for the flow of water in the top of the Radiator.
If the Pump is working 'reasonably well' (it's by no means a 100% check) and the Thermostat has opened properly, you should see quite a flow of water coming in from the top hose and across the top of the internals.
If that's not happening, then after it's cooled down, try to remove the Thermostat housing. When successful, heat the thermostat is a pan of water and see it it opens. https://youtu.be/-1uszG_4B54
If that's OK, then work you way through looking at the other things on the list.
Put the Housing back on without the thermostat in it.
Repeat the early Flow check, can you now see adequate water flow?
It doesn't have to heat up this time as it's not being held back by the thermostat.

Systematic diagnosis is the way forward and prevents unnecessary purchases.

You say that when you stop you lose "a significant amount" of coolant. From where though? Is it from the rad cap, the water pump, or somewhere else? That might be a clue.

Giving it more thought than previously, the compression test usually clearly indicates the more common mode of gasket failure - between two adjacent cylinders, so the results may not be quite so definitive (as a one-off check). But you might fill the radiator full to the filler neck and watch for a regular stream of unexplained bubbles of gas escaping as the engine warms up from cold. The coolant may well have changed colour due to a Ph change if acidic exhaust gases are escaping into the system.

Before jumping to the conclusion of a failed water pump, you might consider (if it was working) whether the car heater is providing the normal amount of heat.

Of course there could be several factors that are all cumulatively adding to the overheating - possibly with one of them being (figuratively) the straw that breaks the camel’s back. Ambient temperature, fan belt condition, badly retarded timing, etc.

myoldjalopy wrote: ↑Wed Sep 06, 2023 10:37 am You say that when you stop you lose "a significant amount" of coolant. From where though? Is it from the rad cap, the water pump, or somewhere else? That might be a clue.

Also, if the owner really is "new" to older cars, perhaps he isn't aware that there is no need to keep brim-filling the radiator after each journey? If the radiator is overfilled the water will expand once hot and you will always loose a certain amount because old cars like these do not have expansion bottles to cope with this. Your aftermarket temperature may (or may not) be working accurately) but the water loss might only be the normal loss of expansion from an overfilled radiator if coming from the overflow pipe? If this is possible and you can still see a water level with the radiator cap removed, just leave the water level alone. You might find that the next time you use the car that no further water is lost. It is worth a try. Modern cars almost never loose any coolant - and a Minor shouldn't either really but If you keep on overfilling, they do appear to

As others have said, we really need to be told where the water is leaking from before we can be of much help - and you haven't reported back with much in the way of clues.

also faulty radiator cap not pressuring the coolant gives lower boiling point and vents water from overflow.

ManyMinors wrote: ↑Wed Sep 06, 2023 2:23 pm Modern cars almost never loose any coolant - and a Minor shouldn't either really but If you keep on overfilling, they do appear to

All your comments very relevant, but the key thing with a modern is that they have a header/expansion tank.

As I said..... "these cars do not have expansion bottles".

ManyMinors wrote: ↑Wed Sep 06, 2023 7:57 pm As I said..... "these cars do not have expansion bottles".

Opps, missed that

Many thanks for all your advice. I have some place to start