This is my last hope. I have an 2005 Cooper that has been to 2 separate garages and no one can seem to figure this out.

It started with a simple overheat. There was a small gasket leak around the thermostat, and it was replaced. This is where the trouble really began. About 10 miles down the road it began to overheat again. I was not able to safely return to original repair garage and went to a closer one to home.

They flushed the coolant system twice with the claim of an air pocket in the line. One thing that was strange was the coolant would blow out the expansion tank?
Then it was the radiator cap, it was replaced and everything seemed ok. Drove for a couple hours then out of no where my heat was gone again and my temp went up again. This time though, no blow out through expansion and the temp reading in and out the radiator were normal and the cap was warm to touch so sensor was tested and ohm readings said it was faulty.

So the garage has replaced the sensor and test drove again. Seemed fine until he turned on the A/C, then overheat again.

The only thing not replaced so far was the water pump, they claim that the flow is good and that the pump is not suspect.

WTF could be going on. I've spent over 600 now on what seems like a witch hunt at this point.

I would appreciate any and all advice or ideas on what is wrong, the closest mini dealer would cost another 200 in tow charges so i'm trying to eliminate that if at all possible. But at this point it may be my only hope.

 

The most common cause of an overheat is a low-coolant issue caused by a leaking thermostat gasket. Sounds like you have addressed this; or have you?
Who replaced the thermostat/ gasket? Are you 100% sure it was done properly? Do not assume that the local repair shop did what you asked them to do. This can lead to a whole lot of grief.

 

Mine's going in tomorrow to get checked out. I have an '03 and took it in cause she'd heat up when going through a drive through or car wash. I was hoping it was just the thermostat but they're saying one of my belts is fraying and that my pump might be dying. Not looking forward to the bill! I'll letcha know if they solve my problem as soon as I can.

 

Overheating while at low idle is a low-coolant problem. Shouldn't have anything to do with belts. Find out why you are losing coolant. You may also have a belt issue, but that's not part of the overheat problem.

 

I checked the coolant reservoir with the help of my friends phone instructions, and it looked a little low to me, and when I brought it in the first time the mechanic said the same thing an that he topped it up. I think tomorrow before I go I'll let her idle for a few minutes and see if that has solved the problem. He said that the belt might not be strong enough any more and that the water pump can't circulate the coolant properly. Or something along those lines...

 

last year I had my thermo/gasket replaced ($300) this year I had to have my heater hose replaced ($200somthing) and that remedied my overheating issues.

 

Thermostat gasket is the most common cause of coolant loss. Next in line is the reservoir leaking. Buy a new thermostat (comes with new gasket) and have them replaced. Most times this will eliminate the coolant loss. Been there, done that, spent the $$$.

 

Would this also explain why my heater only blows hot air while driving and cold air while in neutral?

 

It's time to check for the presence of combustion gasses in the expansion tank; if positive, it's the head gasket.

 

Have replaced thermo/ gasket, rad cap. And heat sensor. Still getting an overheat. I'm convinced it's an air pocket because I drove for 2 hours after flushed for the third time and just out of the blue it went hot again. I also notice that heat goes cold when it gets hot.

 

sounds as if one of the waterhoses has gotten weak and is collapsing under pressure. had this happen to me on a Chevy van, almost drove me crazy before we solved it

 

Is your radiator fan working properly?

 

Mini thermostat housings are plastic crap that MINI has never updated to a better quality unit despite chronic failures. When they leak, you may not see steam or liquid but the reservoir will drop.

I stopped going to MINI because I like to deal with people who will show me the problem and where it is so I can see and understand it. Someone should be able to show you the residue around the thermostat housing if that is ndeed where the problem is, so you can know what definitely needs replacing.

 

ditto on checking the fan

and did the place that did the work know that the MINI cooling system has vent plugs for bleeding the top end of the system? There are high spots that form air traps.

 

The top hose has a large clamp screw that needs to be opened and closed to bleed a Cooper. Its to the left of the radiator as you look at the car from the front.

 

I love this forum! Thanks for all the advice so far. Keep it coming. We did find a cracked screw on the high side bleeder near heat core. This may have been the culprit. We shall see

 

My tank showed no signs of leaking, then one day it went, replaced it and all my overheat issues disappeared.

 

I would suggest that you find a different mechanic. And check that your radiator fan is working properly. The belt also spins the a/c, alternator and supercharger. Definitely top up the coolant reservoir first.

 

I just got it back and he said they couldn't find any leaks but he did replace the serpentine belt because it was fraying. But otherwise, he topped up the coolant all is good. For now at least...

 

OK, a fraying belt should certainly be replaced. Not the cause of your issues. Keep looking. Fill your coolant reservoir to the appropriate mark, and keep track of coolant loss. Radiator stop leak can do wonders.

 

The serpentine belt has nothing to do with powering the water pump. The water pump is driven from the back of the supercharger. This is a weak part of the MINI as the seals around these gears can leak and cause the gear lube to drain out and cause the gears to eat themselves up. This causes the water pump to stop working.

 

Thank you! This is Friday of Memorial Day weekend, my mechanic was closed and I thought I'd check the forums. I did have a slightly low coolant level, fixed that, bled the line and ta da! no overheating. I have a maintenance appointment for my '05 Mini soon and will have the thermostat checked too. For now, I think I'm back in business and can make it through the weekend.

Laurie

 

If you are spending more than $40 for a thermo/gasket, and more than $20 on heater hose and clamps, then you are not utilizing this forum. Not trying to harp, just can't stand seeing people get taken for a ride. I used to be the same way, until I started flying in helicopters in the service, and also working as a mech on them. It was just knowing where the pubs were, where to look in them, and follow the directions. With google today you can look up any how to you want.

 

Forums are great!

They even show you the date of when things were posted

 

My experience at first--overheating, changed the radiator fan due to low speed fan not coming on--solve the problem then A/C not cooling followed by overheating at the mall, no steaming on the reservoir, drove home and further investigate no leak all seem normal then read the forum about water pump gear, put the car on service mode to pull the supercharger and found low oil on the PTO side due to leaking seal. Ordered new S/C with new pulley, new water pump,o-rings, thermostat, belt and belt tensioner and upgraded bushing and stop, new hood latches and cable.
Finally all done ran for about a week then here comes again overheating issue this time the reservoir is steaming when the A/C is on, run ok without the A/C, temperature goes up to 230F and the low speed radiator fan not turning, but i hear the power steering fan comes-on, turn the A/C on then fan comes on then stop and never comes on again, im thinking the low speed fan relay or the coolant sensor. I bled the cooling system, ran the heater etc, etc.... hoping to get some directions.
BTW: I don't see any coolant leak, after it cools-off the reservoir (tank) still more than half way!!