Yaaaay!

Mark. congrats  you need to do  all the other things.. rad out the radiator.. new hoses.. ect.. if you going to use as daily driver.  cheers.. PHD

First, Thank you guys for all of your help. I checked the fan blades and it was installed correctly. I then dug into the thermostat since I already had the parts. It was a piece of cake. It was probably one of the easiest jobs to do on a Mini. The old thermostat looked like crap and the gaskets looked to be original. After cleaning everything up and careful reassembly plus topping off the coolant, I let it rest for a few hours. I went for a ride tonight and so far all is well. No boiling over and the needle stayed right at the little white dot just below the half way point on the temp gauge. It sure feels good to have that behind me now. Thanks again. Mark

dido about the fan blade..  I use the metal tropical ones on all my minis..  aboit $50 from the host. PHD

I would X2 what Dan, PHD, et al have said about Rad. Since you're going through it, and have already had a few overheatings, I'd like to recommend you either get that rad completely checked out by a specialty shop or replace it with a high quality one. I think our host has a "Super Two Core" style or somesuch.

Excuse the obvious quip here, but check that your Yellow Plastic Fan is mounted facing the correct way.

Then, consider doing the stat, hoses, and the other "While you're at its" because you don't want to take out the rad again. Consider checking the low point inside the cabin, your heater core for sludge. Depending on your car's past maintenance, you may be better off replacing the heater core as I think it might be the type with alloy matrix with plastic end tanks and thus hose connections.

Because it is an automatic, change your oil and filter. Then, you'd know where you stand in trying to protect that Auto.

Finally, determine if you'd like to add a Water Wetter or comparable product to aid in the heat transfer of your "radiator fluid".

You're establishing a baseline for your period of ownership, so it might as well be fairly comprehensive.

Stay cool, my friend! Best, MSH

Thank you all for the good advice so far. Our host lists a 190 degree thermostat for my application. I never use the heaters in my classic cars either because I don't drive them in the winter or even when it rains. I bought a thermostat and gaskets with my last parts order I will try replacing that first and go from there. The inside of the radiator looks pretty bad also. The tubes that I can see look fair but who knows what the rest of them look like.

yea..Dan you are right .. I had forgot about that heater thing.. never use in the sunny south..  buy proper thermostat .. the ones from Advance . Auto Zone.  are POS. and most times will NOT even open... use 165F.. PHD

+1 for a bad thermostat. If you live in a climate where you need the heater, don't drill the thermostat. The proper function of a T'stat is to stay shut until the engine warms up and then gradually open to provide full flow to the rad. In colder weather it modulates engine temperature by partially closing to maintain a minimum heat level in the engine. The heater hoses by-pass the thermostat to allow a continuous flow of hot coolant to the heater. Holes in the T'stat defeat the modulating design. the engine can get cooler than optimum and you won't get cabin heat. I tried the six-hole treatment and found I could not get enough cabin heat. Some think the holes are needed because later engines do not have the small by-pass hose between the head and the water pump. Not true or it would never have left the factory that way.

Simple way to test the T'stat: Take off the rad cap and start the cold engine with the bonnet open and let it warm up. Hold your hand on the upper rad hose and wait. You should feel the head get hotter and hotter while the hose remains cold. At the specifed temperature, the T'stat should open and you will feel warmth in the rad hose gradually heat up. Looking down the rad filler, you should also see the coolant flow by, especially if you rev the engine. If the top hose warms gradually with the head, the T'stat has failed open. If the hose dose not heat up and there's no flow through it, the T'stat has failed closed. (The drilled holes would defeat this test.)

Unless your car has a coolant catch-tank, there should be some air space in the top of the rad. If you over-fill it, the surplus will be pushed out with expansion of the fluid and when the engine cools and the fluid contracts, it will allow air back in through the venting rad cap. Old cars are not like modern ones.

When you install a T'stat, make sure you put it in the right way around. On the side with the spring, there is a capsule with special wax in it. This capsule must be on the hot or head side - down in a Mini. The wax expands and opens the valve against the resistance of the spring. If it is in backwards, the engine will overheat.

Bad thermostat. Before your put in the new one double check it by putting it in a pot of boiling water. You can test the old one also by putting it in the same pot. They come in three degree flavors. 

Also, look at your hoses. A bulge will develop on a compromised system. That indicates a weaken hose. Check to see if your hose clamps are tight.

A copper radiator is more efficient in transferring heating. Looks better too. Silicon hoses do not stretch. That becomes a problem when you are putting on the bottom hose on the lower radiator outlet without removing it.

Try. this.. cut heater on full blast.. could have air bubble in it.   drain all your fluids. and have the radiator   ratted out.. or just buy new alloy one from Winning Spares on ebay. about $100  Replace with new silicon   hoses..  that the termostat out and drill six small holes in it..  to make the water flow. do NOT take it totally out. will over head for sure..    you might have blown head gasket ?/ lets hope not..  let us know..  cheers PHD.

Hi guys, I'm back in the Mini game again with a 1996 Mini SPI Automatic. It was built for the Japanese market. I received the car on 8/11/22. Shortly after driving it home, I checked the fluid levels and found a dry radiator. The old 15#cap looked pretty bad so I replaced it with a 13# cap. I topped it off, took it out for a drive and it boiled over and was dry again when it cooled off. I took it to a local foreign car shop and they found a leaking water pump. It was repaired and driven home and boiled over again. I replaced it with a new 15# cap, went for a drive and it boiled over again. So my question is, what could be causing this? The temp gauge pegs when it overheats. I don't go long distances so when I see the needle start to climb, I head for home. Any help would be greatly appreciated. Thank you. Mark