Hey all,

Before I start I have read and searched, I did not find anything like what I am seeing.

So my 03MCS is showing pegged on the needle but it will sometimes come down rapidly but when it’s showing pegged I checked the block and head with a IR thermometer and it shows ~160, I have replaced the t-stat in the past, purged the air from the lines and it’s still doing it. It never smokes or boils over, so I’m leaning to a bad sensor. But I would assume that it would show no temp rather than hot, but I don’t know. Also there is no heat in the car while this is happening, but I think that is a mechanical issue with the heater, when I turn the wheel I hear the baffles clicking and popping so they may be stuck.

Any my thoughts before I start tearing down the cooling system and replacing things?

Thanks,
Mike

 

Thinking the sensor is working on resistance. There is a thread here somewhere and a guy was able to buy the sensor for like $6.00. He researched and found a manufacturer that makes the part without the MINI logo/part number. Let me see if I can find it.

On the heat, you could have plugged heat coil. The other option is to buy a cheap temperature gauge off ebay, around $10. You use the bleed screw at the front (left side or radiator by the supercharger) as the port to install the the sensor. You will need to ground the sensor to the engine and jump a power line to the gauge. Could do all from the hood area.

 

I found the thread I was thinking of but it deals with oil temperature not coolant.

 

I'd say the IR thermometer isn't what you're looking for. External temp wouldn't tell you a ton about what's going on inside.

If you're suspecting there's nothing wrong with your cooling system, I'd pick up the temp sensor and swap it out. It's not terribly difficult IIRC and it's only about $50.

 

FWIW, some years back working on software for an OBD2 data/trip logger and testng this with my Boxster occasionally in going over the data logs I'd spot a very high coolant temperature reading. Just a spike never longer than one reading, which occurred every 5 seconds.

Bad connector. Loose. A bad connection had the voltage level high (pull up on the analog input pin to which the coolant sensor is connected).

So a bad sensor (or bad connection) could result in a very high reading not a very low reading.