As you might recall, I had the following description of a coolant leak a couple weeks ago:

"My wife got back from running errands, and within a minute of parking in the garage, the engine released a lot of steam and then coolant started spraying out inside the engine compartment and onto the concrete floor. I asked my wife if any lights came on on the dash and she said 'no'. She couldn't remember if the fan had been running when she parked."

I since ordered the pressure tester, thermostat housing, and coolant pipe (that leads to the water pump) from ECS Tuning. There had been a small leak from the thermostat housing and a large crack in the plastic pipe.

Checking out the car this morning, there's no more leaking. I took it on a spirited run around the area after it had warmed up. Upon returning, I noticed the fan was not running at all (it usually does so for a minute or so after a drive).

So now the question is, do I have a bad thermostat in the new housing, or is there a fan problem which could have led to this whole overheating and leaking problem in the first place???

How do I check out the fan function and differentiate that from a faulty thermostat?

 

Just inspected the fuses and they look good.

 

If you disconnect the plug to the fan motor and put a VOM/continuity tester on both sides, is the one side of the fan continuous to the other side (in other words is their break in the windings)? (correct answer should be yes) Next, using the VOM/Continuity on one side of the fan motor connector and the other to ground, do the windings go to ground (must be disconnected)? (correct answer should be no)

If those tests are successful, and you are also not going to short out your car, windings are continuous and no windings to ground, if you hot wire the fan motor by-passing all relays, fuses and switches, does it come on?

Comes one: fan is fine.
Doesn't come on: fan is faulty.

 

I thank you for your input--I just wish I understood it better. I have no problem doing the mechanical stuff, but the electrical stuff baffles me. I have a multimeter but really don't know much about how to use it. If anyone has any links to appropriate YouTube videos that would be greatly appreciated. I did a search under "Mini radiator fan not working" and came across a lot of R50 and R53 posts, but not for R56.

I suppose I should monitor coolant temps while driving and see if I'm really exceeding 220 degrees.

 

If you have a schwaben computer tool, you should be able to plot the temperature of the coolant. However, I thought you already concluded the fan is not coming on. If so, next you need to know why. Is it the fan (motor), a relay, a fan, a sensor, a connector, the wiring. Checking the fan motor windings is step 1 because it is easy and that is the most likely what it is if the relay and fuse are ok. You do not need to remove the motor, you can test the motor through the harness plug going into the motor once you disconnect it.

Here is a youtube that describes what to do. If your motor is broken, you won't go have to do anything else, it will confirm it, you will buy a new one and have to remove it and install it.

 

After I replaced my thermostat, the fan ran much less often, because the thermostat was working correctly and the coolant wasn't getting as hot since it could circulate through the radiator properly. Your fan may not be running as much because it doesn't need to now. Just a thought.

 

Yes, that's why I wanted to monitor the coolant temperature, to be sure it was actually reaching the temperature that the fan should be turning on.

 

OK, so I plugged in the Torque app and went for a drive. Ambient temperature was 73 degrees.

Once the car was fully warmed up, the coolant temperature stabilized in a 199-203 range. Highest it ever got was 205. The fan did come on but on the lower speed, and as soon as I shut the car off, the fan turned off as well.

The weird thing was that before I changed the thermostat, the fan would sometimes be running at full speed (pretty loud) when shutting down the car and would stay on for a minute or so even after the car was shut off. Maybe the old thermostat was set at a lower temperature? I don't know, but it seems to be functioning fine now.

 

So it sounds like when the fan is running constantly, it could be a pre-cursor to the thermostat acting up. That wouldn't surprise me. Thermostats tend to become sporadic before completely failing in older cars as well.

 

Not really a pre-cursor, more a direct effect. Thermostats usually fail closed or it takes more heat for them to open up.