Suggestions please? Weird overheating!

[Stromfirth]

It looks like our water is not circulating around the engine...

We have fitted a new temp sensor, and a new kenlowe fan temp control. Had it for a run and the radiator is still cool but the gauge is really high and the engine block is really hot to touch - so I guess it's overheating. The elec fan doesn't switch on as the water in the radiator is still cool and switching it manually wont help (as the water in the radiator is still cool!)
Have any of you come across this before?
It looks like the water isn't circulating, but how do I cure this?
It's a 1000 engine and has no heater.

Any ideas???

Should also say, I have tried running with the cap off and there is no water movement
also, have squeezed the hoses without success!

[dingbat0]

Hi, sounds like the impellers on the water pump could have corroded away, or you could have a blockage, have you tried flushing the system, both ways? Mick.

[Stromfirth]

Thanks Mick - The engine has been out and flushed and it's a new radiator and new water pump as well! We took the thermostat out and boiled it - it did open, but it could be faulty so I'm hoping a new one will fix it?
We just took of the blanking plate on the top of the head off to see if that would bleed any air out without success.
It's still hot below and cold in the radiator.

[Doug G]

I shall be really interested to find out the cause of this problem . . . . . . and the solution.

[Stromfirth]

I'm off to take the thermostat out altogether this morning and see what happens!

[fistral fig]

My suggestion was going to be remove the stat and try it, but if that does not cure it don't forget that new parts does not always mean they are correct or OK? there is mention on another thread about the water pump impellers being to deep and touching the cylinder liners, could yours be to close for example, because with no stat you should see movement of water if the rad is not choked of course.....FF

[Robin Jones]

FF, the pump impeller fouling was one of my first thoughts. But, wouldn't the belt be screaming on the pulley?
Air bubble perhaps? Have you run the car with the radiator cap off to check for coolant flow?

[fistral fig]

Well yes I agree you would think so, unless it had damaged the impellors and are trapped and just spinning on the shaft? I had that with a Ford Granada years ago with a QH new pump, I haven't looked in my moke rad and seen the water flowing but I have seen plenty of others over the years once the engine has got warm and the stat has opened, I think its worth double checking for the sake of a gasket.........

[Doug G]

In my Mini Moke, I have:-

- put in a new radiator

- put in a new water pump

- removed the thermostat. (various sites suggest that this is not a good idea)

- put water in the radiator (recommended)

- put water in the overflow tank. (recommended)

- swapped the caps around several times ie standard cover tank on overflow tank and spring loaded cover of radiator and tried them vice versa.

[Stromfirth]

The problem is bigger than we thought!
Thought the actual gauge may have been faulty so we played around with a thermometer and found the thermostat wasn't opening until about 90deg. (Should be 82)
But, When the thermostat was taken out, the water was circulating but it still overheated.
With the new radiator, water pump, hoses, sender etc fitted and all sounding Ok we decided that the bottom of the water jacket must be clogged up with it standing for so long.
We opened the drain plug at the back of the engine and not a drop came out'
So, tonight the head is off, after about an hour of poking around with a bit of wire and a large screw, I eventually got water to run out of the drain plug.
Am now debating how to clean it out - caustic soda? Drill out the ports? Would Rad flush be tough enough?

Also a bit perplexed as, when I put the air line down each hole, some sent up a cloud of dust - looks like the water is not getting around the block...

I'm off for a large Gin!!!

Note:- this is an old 1000 engine with no header tank!

[grantourer]

Hi, when Rod at Southam Mini rebuilt my Moke engine, he took the core plugs out to allow the block to be properly cleaned out. This may not be easy to do with the engine in the car.

[Doug G]

The problem is bigger than we thought!
Thought the actual gauge may have been faulty so we played around with a thermometer and found the thermostat wasn't opening until about 90deg. (Should be 82)
But, When the thermostat was taken out, the water was circulating but it still overheated.
With the new radiator, water pump, hoses, sender etc fitted and all sounding Ok we decided that the bottom of the water jacket must be clogged up with it standing for so long.
We opened the drain plug at the back of the engine and not a drop came out'
So, tonight the head is off, after about an hour of poking around with a bit of wire and a large screw, I eventually got water to run out of the drain plug.
Am now debating how to clean it out - caustic soda? Drill out the ports? Would Rad flush be tough enough?

Also a bit perplexed as, when I put the air line down each hole, some sent up a cloud of dust - looks like the water is not getting around the block...

I'm off for a large Gin!!!

Note:- this is an old 1000 engine with no header tank!

Aha. Now I know my next job!!!!!

[Doug G]

Can you post a pic of which plug you undid?

[grantourer]

Hi Stormfirth & Doug. The plugs marked 2 are the "Core Plugs" these seal the block to allow water to circulate. They also rot over time and can fail, usual cause of failure is using water with no antifreeze over an extended period.

[Stromfirth]

Looks like 27?? Drain plug under the steady bar at the flywheel end on the back of the block.

May have to resort to taking the flaming engine out again and excavating the core plugs, but i would like to avoid that if possible - at least this year! Was hoping to have it running for the summer.