After doing valve work on my 2007 Mini Cooper S, I believe I'm having an issue with the thermostat. The lower radiator hose is not getting hot and the cooling fan is not coming on. Does this sound like the thermostat is not functioning? There are no CEL codes, but the car idles rough until you give it some gas, but as soon as you let off, it stumbles again.
Thanks for any help.

 

The '07 lower radiator hose doesn't flow until MAX A/C is used, or maybe during some other unknown to me condition. It seems to be an "emergency" water source for the engine. I use it to keep my engine from overheating during high traffic, stop/go conditions.

Rough idle and stumbles can be most anything, but if it was OK before your valve work, I'd suspect something with workmanship. It's common for timing to slip slightly due to chain tension, have you checked it after assembly? Maybe ensure your coolant has been bled and level is full. Fan fuse is OK?

 

There's no flow through the radiator while running the engine...Only when running the AC? I thought the flow went through the radiator. The cams still look to be in time, the chain doesn't look loose, and I have no CEL. Wouldn't I be getting a CEL for misfire if the timing was off?

 

Take a closer look at the hoses. Pretty sure the lower hose connects to a "tee" that comes from the rest of the radiator. I haven't dug into the flow in detail, but know for sure that "Max A/C" adds more coolant to the engine. I also tried to add a coolant gauge to this lower hose --- never did heat up. So yes, coolant flow is thru the radiator, just not using this lower hose. Timing can be slightly off and still not throw a CEL for misfire. Don't go by looks, newTIS has a method for checking tool fit with a feeler gauge, it's located in the premium cam install procedure.

 

Thanks, I'll look a the hoses closer. I locked everything down when changing the valves. Guess i'm gonna have to take it in.

 

Ignore everything I said about coolant flow. I did a little more research and found my "reservoir" concept is all wrong. Still get added cooling when using "MAX A/C", just not sure how it happens.

 

When you run the A/C, the radiator fan is turned on continuously rather than cycling based on water temperature. This is to ensure air flow over the AC condenser regardless the coolant temp.
On Base models, the coolant system is pretty straight forward but on the “S” models (N14,N18 engines) there is an electric auxiliary water pump and a thermostat heater. Why they are equipped that way and the operating principle of that system, I don’t know but that extra electric coolant pump may ALSO be operated in conjunction with AC operation.