Did anyone check to see if there was pressure in the cooling system from a leaking head gasket? These cars are not serviced very well and the problem with the long life antifreeze is that it's protection diminishes with exposure to air. This is the problem GM had with Dexcool. Exposure to air from leaks and low coolant levels actually accelerated corrosion causing all kinds of problems. A rotted head gasket that is leaking compression into the cooling system will cause the engine to overheat quickly by disrupting coolant flow. There are easy tests for this so your local pro should be able to check this and get a definitive result.

 

i asked him if he had a compression test and leakdown test done but he never responded...

 

With the reservior cap off, have someone give you a liitle throttle, and watch for a stream of coolant into the tank (from the small return hose at the top). I've found that if you hold a flashlight to the tank, you can see this very clearly. If there is no flow, either the system is airlocked near the water pump, or the pump is not turning (as stated previously, with the pump off, you cannot just feel the drive, you have to spin the supercharger several times while applying pressure on the pump drive).
If you're pouring coolant into the tank to fill the system, then there is lots of air. Take the top radiator hose, separate it from the bleeder connector and pull it up. use a funnel and pour coolant into the radiator until it come out of the upper hose (engine side). Now close the system, fill the reservior half way and start the car again. Watch for the coolant return into the bottle.
Good luck
--Dan

 

Do you have bubbless comming up in the coolant return bottle? If so could be head gasket or head. Do a compression test.

 

sounds like early stages of a leaking or blown head gasket. unscrew yr oil filler cap, if there's a white-grey foamy substance on the cap's underside, that's coolant mixed with oil and a sure sign of a leaking or blown HG. If it's there, have yr car towed in as soon as possible, you do NOT want to drive it much more 'cause you will damage the engine even further. Another sign of blown hg is on startup the exhaust is white and has a NASTY sulfuric smell. :-P

This was the only major mechanical problem Ive had on my 1986 Toyota PU. $32 for the gasket, $590 in labor.

Im surprised yr shop didnt run a compression test, that's not exactly trying to pinpoint a problem before repairs are initiated, repairs that may not help.

 

The mechanic I took the car to is one of the best, Voit Ritch, a veritable legend in the BMW world. He did not deck the head, did analyze gases from exhaust, did not think it was a head gasket/warped head. He said Water Pump and Thermo, so i replaced those myself. Actually did not blow up when I put it back together. After my initial elation, I noticed the car behaved the same way as before. It is most likely a blockage in the coolant lines somewhere, I continue to overheat. Do not have access to a lift, only so much I feel comfortable doing without one. thank you for all of the assistance. i will update when fixed or solution is found.

 

Try bleeding it with the front end lower than the rear end. Me and a buddy swapped out his radiator once, and we thought we had it bled properly until we re-bled it with the car tilted with the front lower than the rear. That solved the issue. Also, I just had to have my supercharger replaced, as I had the same issue someone mentioned earlier. The driver side of the supercharger went bad and stopped turning the water pump, leading to an overheat. Did you ever hear any rattling bearing sounds before the car started overheating?

 

I read where you re-checked the thermostat installed, but-it IS pointing the correct direction, isn't it? the way it comes with the o ring seal attatched to the new t stat from mini, it would be tough to install it backwards, but it could be done, meaning the t stat would never open and allow circulation. I just checked a new housing and T stat on the shelf here, and if you did it just right, you could install it backwards.

 

I believe so, the spring is pointed inwards toward cylinder head. thanks for the continued assistance.

 

yeah thats the way it goes...
please keep us updated on what the outcome is, i'm very interested in the source of the problem

 

Here it is first of the year and three weeks my mini has been down. Just going to swap the cylinder head with the first one I can find at this point, deck the old head to see if it is warped or not. If anyone has a spare head layin around they want to donate, or sell inexpensively, or take my entire savings for, I am in need. Also will need a gasket and Stud bolt kit. Thank you all for your assistance, too bad I could not report better news. New Year, new luck, right? We shall see.

 

run the car till it gets hot and then do a compression/lakdown test, before you start removing major engine components... has anybody done a compression test on your car??? a simple comp. test will go along way on this matter...

 

Just a though in case it's a simple fix...Did you bleed the cooling system out of both bleed screws? There are two on MCS's. Before I knew about the second one, I had some overheating issues after changing my coolant...even with solid fluid coming out of the upper bleeder. The second one is an 8mm bolt down below the back-right corner of the intercooler. There's a heater hose coming into it. Taking the cover off the intercooler makes it much easier to get to.

 

Can you believe it?

Decked the head and found a crack.

New head being sought ferociously.

three weeks and $1500 later, here I sit.

Will update when new head is installed!

if that doesn't cure what ails her, I may have to put her down

gotcha

 

does your auxiliary cooling fan turn on? try driving the car and see what happens. I did not read many of the previous posts in depth, but If you have access to any scan tool, I would try to pull up the coolant temp sensor voltage to see if it is within spec. If it is faulty, it may not be telling your aux fan to turn on. I don't see why the power steering fan would affect coolant temp, i just know it burns out steering pumps when they fail. Good luck sorting it out.

 

I should read the last post before I comment next time.

 

please tell me you or the tech did a compression/leak test before expending $1500 and it didn't show anything related to a cracked head... at least it will justify wasting all that money

 

I needed this diagnosis at the beginning, and i would have saved some of my hair and money. The gears that turn the water pump on the supercharger have given up the ghost. Now installing new supercharger, add it to the water pump, thermostat, and new cylinder head, and you have a pretty expensive fix. Will update this thread when my car is driveable. thank you for the advice.

 

Finally back on the road today. Replaced the supercharger, et Voila!
Don't know for sure if we cracked the head looking for the problem, or if it was already damaged, all I know is this was the most expensive fix I ever want to have on my Mini. Cylinder Head, Supercharger, Water Pump, Intercooler, Thermostat, all replaced to fix this. Hope my battery comes back to life, as the car has been sitting for weeks, only turned on to bleed and diagnose during that time, or I will have to replace that, too. Good news is I now have a Ported and Polished Head! as well as a new supercharger, and put my coilovers on while it was down. Haven't had a chance to put them through their paces yet, but looking forward to it.
Thank you all who spoke up to help. Thank you as well to those who chastised me. Hopefully this experience of mine will help others find their supercharger problem more quickly, resulting in a less expensive fix.
90k to 120k is the zone where this happens, if you have a smaller pulley then you are especially likely to have this happen. If you overheat unexpectedly, pull over and have the car TOWED! do not drive it anywhere, swap the supercharger, and bite the $500 bullet. It is much better than my bill, I guaranfukn-t-it! Be well

 

Loki, during any of your problems did the MINI "rev" at idle. Mine has been doing this. At first, it would rev from 800 ~ 1400; now it idles at 1100 and revs up&down to ~2000 when warmed up.

I suspect a head gasket (I have the milkshake in the oil syndrome, live in southern USA and drive 60 miles to work at highway speeds).

If it is supercharger/water pump, I do not to pull the top end.

 

Glad your car is fixed...I too wonder if the Supercharger issue was the original culprit, and perhaps the head cracked because of the consistent overheating? Let me ask you, when your car was running and you were standing near the front of the car, did you hear a little bit of a rattle. I heard that this is related to the Supercharger issue, and if so I want to prepare for this when it happens to me!

 

Yes I had the rattle, though perhaps not as pronounced as some of the others I have heard of with this problem. I do believe the supercharger was the root of all my problems, but hindsight is, well, hindsight.
In response to the question about revving, it did rev a little, but I put that up to the cooling fan not working due to a blown fuse. The coolant milkshake is pretty much a dead giveaway a head gasket is part of the problem. Take my advice and deck the head while you are replacing the gasket. It will save you time if not money and take another issue off of the table. Good luck and let me know if I can be of any help, I feel like a true Mini wrench now that I have conquered this debacle. With all of your help of course.