Heya folks...
So, I have a 2008 Cooper non-S convertible that started overheating about a month ago.

I did some research and figured out that the stage 1 fan was not kicking in, and that this was a common problem - I fixed that by replacing the fan relay with an aftermarket part... the fan kicks in when it's supposed to now.

However, the engine still gets too hot and the only thing I can think of is that the radiator fluid seems like it may not be circulating at all (not that I've ever paid much attention to it, but I thought that you should normally see the fluid drop down when the engine is running and it doesn't seem to).

Any ideas?

TIV

-Robin

 

Bad water pump or stuck thermostat...

 

Need more info about "too hot". These cars run at 220 deg and I have seen as high as 235 on a track day...

Are you getting warning lights, is this a gage reading or just your hand on the engine?


There is a "clutch" action where an idler pulley engages the water pump with the belt once the engine come up in temperature (don't know exactly what temp that is though).

 

Okay, I plugged in my OBDII and monitored it while it sat and idled.

The stage 1 fan kicked on at right about 221 degrees... it continued to climb up to about 231, where stage 2 kicked in. However, the temp continued to climb and I finally shut it off at about 240.

I initially noticed the problem when the temp gauge on the dash would suddenly go from halfway up to all the way up in a matter of a few seconds - I haven't since let it get to that point, and couldn't say what exact temperature it was when that happened... it was probably bad though ;-)

 

I occasionally see 235 on hard runs but then it drops off fairly quickly as well. i have never watched it while it just sat at idle but remember sitting at idle on a hot day in southern california will make it run high.

I would drive it around a bit and see what the temps get up to on a normal drive or hard drive thru the mountains if you can. if it gets up above 240 and stays there then you definitely have a problem if it bumps up there and then drops back down probably not a problem. Just remember it is designed to run at 220-225 any way.

 

Yeah, so right after I posted that I took it for a quick drive to lunch (Casa Corona in Fresno... yummy, BTW)... about 1.5 miles away.

I occasionally glanced at the temp while I was driving and it seemed to get up and stay around 240 if I sat still for very long - If I was moving then it would go back down to 220 or so (it's a nice day today at about 65 degrees).

My concern is that I never noticed the stage 2 fan ever even coming on at all before all of this started, and I'm sure I would have noticed it because it's quite loud... even during hot summer days in Fresno, which can sometimes get up to 110F.

Lastly, the OBDII reader doesn't show any codes and never has.

Is there some way to go about testing the water pump? I'm assuming it's a pain in the *** to get to, as is just about everything else in this engine :-(

Thanks.

 

So an update:

I haven't been able to drive it much as it is still overheating and I haven't had much time to look at it. However, I may need the car in running condition over the next day or two and need to get this solved.

I did a little more research in an effort to narrow down the cause of the problem. I figure that it can't be a failed thermostat because I'm not getting any OBDII codes whatsoever, and I would be if it were stuck open or something.

The one big hint is that the fluid reservoir is way low again. I've read that I should check for leaks around the reservoir itself, and or that the gasket on the thermostat could be worn and leaking. Otherwise, it could be a worn clamp screw on the top hose to the left of the radiator.

BTW, the car only has 35k miles on it.

 

Not true; you can have intermittent issues without seeing a fault code / CEL.
Besides, a generic OBDII scanner will not read specific MINI-protocol faults.
You may be overlooking something completely with a generic scan.

If you're having issues with temperature at a stand still, I'd be looking at water pump and radiator fan operation.

And with the vehicle only at 35K, why haven't you brought this concern up with your local dealership for warranty reasons?

WAIT, if the fluid was low, and you've sucked in air into the coolant system, have you properly BLED the system via the thermostat bleeder screw?

- Erik

 

So yeah, okay... I should run a detailed diag then?

Something else I noticed. I refilled the reservoir. I never specifically paid close attention before, but when you start the engine in most cars, doesn't the fluid in the reservoir get sucked down into the pump system i.e. the level drops??? That doesn't happen, even when the engine is at 220F+.

The fan kicks on as it should after having replaced the relay.

And no, didn't know to bleed the system, although it was on my list of things to do today.

 

Ah, this might help...

"The pressure/filler cap for the cooling system on the Cooper/One is not on the expansion bottle, that is only a flip-off cap. The pressure/filler cap is at the gearbox end of the engine, between the cam cover and the air filter intake hose. It has (or should have) a yellow warning sticker about not opening when hot. It is sometimes difficult to open as it has the spring for pressuring the system, press it down and rotate anti clockwise. Fill the coolant here, then top up the expansion tank to the correct level. Turn the heater control to hot and run the engine, topping up the coolant as it circulates and the air comes out. Open the bleed valves and let the air out until coolant flows, then close the valves. When you're happy that the system is bled, turn off the engine and put filler cap back on. Make sure the level in the expansion bottle is correct."

 

Bleeding it... what a concept. I just stuck a bunch of leeches on the radiator hose and it's good to go now!

Really, I had to bleed it three times, but now I can drive all I want and it never goes over 210. I think I can live with that.

Thanks!

 

this thread is why I love NAM

 

Great catch on the bleeding of the system. That is overlooked quite a bit on coolant issues. Glad you got it fixed. Way to go bluefox280!

 

Can someone explain to me what is a stage 1 and stage 2 fan? A what temp does it kick in?

I think I am experiencing a similar problem. My scangauge reads my water temp around 105 C after 15 minutes of driving. Is that normal?

 

105C is not overheating, it is normal operating temperature for the coolant. The faster your coolant gets to that temp the better.