Engine Drivetrain 2nd Gen S Most liked posts in thread: Overheating - Need Advice

If you have a head gasket leak it won't manifest itself until hot in most cases. The gas will displace coolant in the head causing overheating. Find a shop with an exhaust gas analyzer for an accurate test; another tool is this http://www.bosstoolsupply.com/index.asp?PageAction=VIEWPROD&ProdID=11810; I've seen it used with good results.

On a low mileage car obstruction of the radiator is not likely, but any radiator shop can test quickly if you take the radiator in while off the vehicle.

What is happening that you consider to be abnormal?

 

While I think 240 is hot, there's no mention of hotter temps or the expansion tank cap blowing. When coolant boils, it converts to a gas which becomes much hotter and creates greater pressures. It sounds as if the system is able to maintain a temperature ceiling, and it does have the capacity of recovery, symptoms not indicative of severe overheating.

Tried bleeding the coolant system yet?

 

Could the fan belt be slipping?

My car does not gain temp on the track (water temp, the oil temp climbs to a point, then stays the same, depending on the ambient temps) even after a whole session.....

 

Track = 240 (used to be 190 -200)
Street = 230
1. Can you get some datalogs from the ECU? This may provide more confidence in the measured values as opposed to the occasional glances at a gauge while on the track. This will definitely give you more data to study and look for relationships to other parameters (i.e. rpm, speed, boost, etc) at the very least.
2. For my R53, track = 200, and street = 194 as a point of reference.
3. Can someone provide data on what is normal for an R56?
4. Have you considered just yanking the thermostat on your 'pretty much dedicated track car' ?
5. Is it possible that the oil cooler placement has limited flow to the radiator? With 230 on the street and 240 on the track, I keep thinking about air flow. Provided of course that there are no coolant flow issues, and I agree this is unlikely.

 

'Little' is the operative word, it is really small. It is more of an oil temp conditioner than an actual cooler. Meaning it has greater function in quickly raising oil temps when the engine is cold, as opposed to lowering oil temps when the engine is hot.

I understand your frustrations, something has changed and is causing the higher track temps. I would think that a weak link could be the complex thermostat device. As mentioned above, is it possible to remove it from the system just as a flow/temp test? Assuming the set points are ECU controlled, has the ECU been touched lately, or rather coincident with the symptoms. I wonder how difficult it is to read the set-points to verify the values?

 

As Brian said, "normal" temps for my R56, via Scangauge, are 220 for street driving and 190 for the track.

 

Damn, that thing IS a heart shaped device. I hate changing parts as a shotgun approach to remedying a situation, but I presently do not see a better path to take.

Also on your tune, I have complete confidence in your original tuner, just did not know whether or not any others had been in there. Clearly, with you having the Dimsport flash tool and swapping tunes, you have eliminated that possibility.

Need some input here folks!

 

So, how's the overheating issue?

Did the new thermostat get installed? Kinda hard to test though without a good hot track session.

 

Good luck...

 

Yes, definitely good luck with today's test. Hopefully you can get it back down to the 195 range for the track.
Also, as Keith pointed out, make sure that system is well bled as air pockets are hot spots, also they just expand and force coolant out of the reserve/overflow tank pressure cap. Unfortunately, I do have some experience with this mess. After some careful and thorough bleeding on my R53 the next track event (which had 15F higher ambients) was accomplished with no coolant overflow mess.

Also, for your dedicated track car you should consider a much lower than MINI recommended % (maybe 25% instead of 50%) of antifreeze in the coolant as well as running Water Wetter. Every little bit helps.

 

Grrr, that has got to be frustrating. While I do not have a better next step at present, head work might be jumping ahead a little bit.

So exactly what did you see as a max hot temp? Was it 195ish, 215ish, or way up in the 240 range? I mean, did it get any better?

 

Ok, maybe splitting hairs here, and I definitely agree that 240 is too high; however, as Keith mentioned it is not technically 'overheating'. Sure, it is too hot and the issue must be remedied, but some of the classic symptoms of overheating are:
- Coolant temp rises, and then keeps going, almost in a runaway thermal condition. Here though, it roughly plateaus at 240, and can be brought back down to more normal temps with more mild running.
- Typically an overheating condition is accompanied by boiling over and spewing coolant everywhere.
- Also, on a modern car I would expect some codes to be thrown

So yeah, it is way too hot, but to me it is not technically 'overheating'.

Back on the electro-mechanical thermostat, it does not seem to be executing the 2nd setting for spirited driving.
- If it is not the heart shaped device itself, then could it be a control signal that actuates a valve to increase the flow?
- Where is the sensor/temp probe? I am guessing it is #5 in the exploded view diagram and that is has already been replaced. Hmm...
- How about the spirited driving signal? Is that determined by the throttle position sensor? I am not sure.
- So, you added an inline coolant temp sending unit that feeds the gauge. Could something have changed there such that it is now limiting flow in that line?
- Check all related electrical connections and connectors again. Is there a corroded wire/line somewhere?

- Also what about the FMIC, are you getting proper air flow threw it and to the radiator? Did you install a larger FMIC recently that is limiting fresh air flow to the radiator? Neither is likely, but worth considering.

Just throwing stuff out there, maybe something will click with one of the experts out there.