Morris Minor Owners Club

My little moggy didn't like the heat over the last couple of weeks, and has overheated twice, coming to a halt with an alarming amount of steam. On the last occasion the over revving sounded like she was in the wrong gear and I couldn't get her in the right one, when she cooled down the gears would select. I haven't attempted to drive her since, deciding to order in a new water pump and thermostat, along with some new hoses.
Today I opened up the thermostat housing, which had been sealed with a clear sealant of the shower seal type. There was no thermostat in the housing! how will this have affected the performance? why might it have been left out? will putting in a new one adversely affect the set up? Could it have had anything to do with the overheating?

I discovered that the water pump appears to be fine, but the radiator isn't the best. Any advice would be much appreciated.
Chrissie

I don't understand the 'over revving' comment - was the clutch slipping??? As for the overheating - the thermostat will have been removed to disguise a chronic overheating problem. Probably because the radiator is blocked/silted up/fins have disintegrated. You can try flushing and reverse flushing - it may do some good - but a new radiator will be a more certain fix. The engine block may also be silted up - but try a new rad first. Fit a 74 degree stat - running without any stat can cause the back end of the engine to overheat badly - so it is important to fit a stat. Also inspect the clutch linkage - is there ~ 1" of free play at the pedal?

As above but I don't understand not being able to get it into gear,untill it had cooled down How hot had it got if it effected the gearbox/clutch. If its been that hot,allthough I don't see how it could effect gear selection,then you may be faced with a lot more work,than just a new rad.

Hi guys, thank you for your advice, the rad isn't as bad as on my other moggy, I have it at home now to flush and back flush through. I have an 82 deg thermostat arriving today, I didn't see a lower one than that, hopefully the thermostat will be okay, when I got the car the heater (Smiths) was disconnected and a bypass hose fitted, I reattached it after flushing it, back in the cold days.
The screaming of the gears was very scary, I was coming off the motorway and trying to spot a place to pull over, it wasn't synching and the car was revving very hard but travelling slowly, I tried a lower gear but couldn't sync it. I put the clutch in and coasted off the road.
There isn't much left in the clutch, certainly not 1 1/2" Its a 948 1959 Saloon,
I also ordered a new water pump but the present one looks newish, what sort of testing should I do to try and diagnose the overheating problem?

kennatt wrote:As above but I don't understand not being able to get it into gear,untill it had cooled down How hot had it got if it effected the gearbox/clutch. If its been that hot,allthough I don't see how it could effect gear selection,then you may be faced with a lot more work,than just a new rad.

It wasn't as hot as when it had overheated at the slow changing lights the previous week, I wondered if it is a separate problem.

One check I'd do, first of al,l is that the oil level in the gearbox is correct.For that matter that checking that there is any oil in the gearbox !
Bob

And in the rear axle... Or are the brakes dragging? The 'revving' could only be due to the clutch slipping if the car was in gear and barely moving. Gearbox seizing up as mentioned above is certainly a possibility.

Using a bypass hose in place of the heater is a bad idea unless the heater valve is closed - however in combination to a missing thermostat I'm not sure if it would cause the normal issues.
Basically the interior heater gives some flow restriction and acts like the normal radiator. Just adding a bypass allows hot water to return to the 'engine inlet' (rad bottom / outlet pipe) i.e. it effectively bypasses the radiator.

The Minor cooling circuits are very robust if the normal components are in place and in good order. However after 40 to 60 years of use with varying degrees of TLC, it's possible for the heater to block up, the radiator to block up, the water pump to loose all blades etc. etc.

After flushing the rad and re-commissioning the car, it's worth to check if the radiator is doing it's job. On a warm day after a decent drive, the water in the bottom hose should be coming out of the radiator warm, but not hot (easy to say, hard to quantify). If half the rad channels are still blocked, it will flow ok, be much less effective.