Radiator Fan Always running on High

[Mr_Boom]

Hello, I just passed the 40k mark with my 2008 MS3 and I have my first issue (although a minor one) with stock parts...

A few weeks ago I ran in AutoX event with 95+ air temps on a huge patch of black asphalt. Typically when I run I will let the car idle in-between runs...which normally takes around 15 minutes.

Since I ran this event, I have noticed that my radiator fan is now always running on high. In the past I could only hear my radiator fan after shutting down the car, but I can hear it while driving around the street and idling at stop lights (and it sounds like it is running at a much higher speed than the speed at which it runs after shut down). When I turn off the car the radiator fan seems to go down to the normal shut down speed. Water temps look normal.

Has anyone had a similar issue before? I'm guessing there is some kind of sensor between the thermostat and radiator fan that is messed up, but I'm not sure exactly what / how easy it is to fix this problem. Thanks.

 

[MikeHTally]

Does the fan run when you first start the car, or once the fan starts, it's on high? I didn't even know the fans were multi-speed. Mine only runs on very hot days and the combination of leaning on it some (or maybe I only hear it when it's in fast mode).

 

[blursports]

Get a dashhawk see what your temps are. I had to change out the thermostat at 20,000 miles. The temps were at 210 all the time. 190 15 should be the temps of the coolant. Eventually it jumped to 230 one day. The coolant gauge doestn't move in the "hot" area until 235+....

 

[Mr_Boom]

I do own a Cobb AP, so I drove around watching coolant temp. for 15-20 min. today when I got home from work. No A/C or fans were turned on for the whole drive.

Coolant temp starts at 102 and steadily climbs to the low 200's and actually settles at 228F when driving on the street. When driving I can barely hear the cooling fan running...but it does start running around 220/225 F. When I idle at stop lights the coolant temp jumps from 228 to 232 to 235F...and for each interval you can hear an audible difference in the sound level of the cooling fan as the temp gets higher. At 235F the cooling fan is blaring pretty loud, but when I shut the car off the cooling fan immediately goes back to the regular sound level after a normal shut down.

The whole time I'm driving, the temp gauge on the dash does nothing out of the ordinary. The gauge moves up to around halfway after a few minutes of driving (when coolant temp reaches ~190F) and stays there for the entire drive.

My initial thought with this issue was thermostat, so I already had one on order that will be showing up tomorrow. I plan on switching it out (which I heard is a pain in the ass) and flushing the radiator...I'll post results when complete.

 

[JReichle1]

Also clean off your radiator and a/c condensor. Too many butterflies can disturb airflow. What coolant/water ratio are you running?

A lower temp thermostat might be all you need...

 

[Kain]

As someone who has switched out the thermostat, good luck. It's not difficult, but if you have meaty paws, there is very little space to work with. And prepare for a mess as you have to remove a few coolant hoses in order to get access from underneath.

 

[8.5MS3]

228 is high. sitting in bumper to bumper i hit 200 tops. normal driving is in the 180-190 region. as others have said Tstat may be toast

 

[Sporty3]

I noticed a similar problem when my thermostat was stuck. The needle on the temperature gauge would climb very close to the "H". Even after shutting the car off, the fans stayed on for almost a minute at full blast.

I had the thermostat replaced under warranty and it went back to normal. Then I got a DH and one of the parameters I'm monitoring is ECT. I get an average reading of about 187F normal driving and it gets as high as 210F in bumper to bumper driving.

Hope changing out your thermostat resolves your problem.

 

[BillTheCat]

My coolant temps here in FL in the Summer stay below 210 as long as I am moving. At some stoplights & such, they will occasionally hit 215-216 with the fan on high, but that's about as hot as I recall seeing the temps go.

This tidbit is from another make & model, but the electric fans in the first generation new MINIs were multispeed fans, and the low speed resistor would commonly burn out, leaving you with a one-speed fan. Don't know if that is a possibility with the MS3, but food for thought.

 

[Mr_Boom]

Survey says...thermostat.

I ordered a new thermostat from the internet (Stant Part #48728...which several internet sites show as being a fitment on the 2008 Mazdaspeed 3) and got to the installation part last night. Problem is the inlet for the radiator hose on this thermostat is about 1.5" longer than the inlet on the OE part...which runs it straight into the AC line.

So after a lot of straining/pulling I was able to get this thermostat bolted on...but it is definitely not the correct fit as it's wedged against the AC line...which of course will not allow the thermostat to seat all the way against the block. But I am able to drive around and watch the temperatures now(which now settle around 190F and peak around 210F in traffic), it's just the fact that I'm slowly leaking coolant where the thermostat seals against the block that's the problem.

Next step is to call the dealer and order the exact OE part so I know it will fit correctly, and do the installation all over again. PITA...but I did learn some lessons:

1. Mazda engineers are pure evil, and I'm pretty sure they designed this car to be as difficult as possible to do self-maintenance on. Things like having the bolt for the auto-tensioner perfectly placed where no socket wrench can fit, etc.
2. Stant Thermostat #48728, although listed as, does not fit a 2008 Mazdaspeed 3.
3. The stock water temp gauge isn't worth two craps. The difference between running 190F and 235F is literally 1 tick mark on the gauge.

^ Wrong thermostat. I'll update pics to show the conflict with the AC line.

 

[Kain]

I have the part # at home, but mine looks similar to the pic. Who knows, could be a slight variation from a N/A 3 T-stat.

I found the easiest way is to start removing hoses from underneath and use a 1/4"-drive 8 mm socket w/ extension. Perhaps an angle joint, too, I forget. There is NO space to do it unless you have the right tools.

 

[BillTheCat]

Thanks for sharing the details of your experience. Hopefully, your difficulty, while minor in the grand scheme of things, will save someone else a minor headache later.

 

[ericm]

Modern car temp gauges aren't really gauges. More like three state idiot lights: cold, normal, hot. Even the ones marked in degrees. My VWs gauge needle will point at 190 when the real temp is anywhere from 180 to 230. You need a real gauge to see what's up. The stock sender is ok, it's the gauge.

BTW, you let the car idle for 15 min between runs? That'll heat soak the intercooler quite a bit. You will be lacking power on the next run. Can you park with the engine off and hood up? That'll let the engine compartment cool off some.

 

[Abysal]

I had the same exact issue; my radiator fan would turn on and run high after 5 minutes of driving. I suspected the thermostat (even thought the needle would not move) and took it to a dealer 2 summers ago. They gave me the run around and said it was normal, I was furious. I ended up buying a $35 thermostat and replaced it. Problem went away, car had 20k on it.

Last summer my dad's regular 2.3 mazda3 hatch did the same thing. This time I had a ODB tool and monitored the temps; his were going to 238 F; while normal operating temp is 190 F - 210 F. I made a print out of the readings and took it to another dealer; they fixed it under warranty with no problems. (also replaced the thermostat).

It appears that in both cases it was not opening all the way.

 

[Sport6]

228 is high. sitting in bumper to bumper i hit 200 tops. normal driving is in the 180-190 region. as others have said Tstat may be toast

I agree, mine temps are usually 187 but at the highest it has been 208 on a 95 degree day in traffic (with a front mount).