Aux fan not engaging at right temp

[trackjunkie21]

So for the past few days I've been running the e30 without any fan besides the aux fan just to see if I actually needed an extra fan. Well I bought the lower temp fan switch (81*/88*). The fan still doesn't engage at that low of a temp, the fan engages pretty close to red and the high speed never kicks on. When I press the a/c button, the fan comes on, which is good and all but why is the fan kicking on so late? Is it the resistor that's on the fan?

[nando]

you sure the low speed isn't the one that went bad? 81c is near the 1/2 mark.

[herlsy]

If the resistor on the fan was bad, it wouldn't kick on on low speed. If it's coming on with the AC button, thats the low/normal speed.

It sounds like it's possible that your temp is getting to 88 but maybe the high speed isn't coming on?

Have you checked the fuse/relay for the high speed fan circuit?

[nando]

if the low speed was working it would kick on at 81c too, it doesn't sound like it's turning on until the high speed relay triggers.

[herlsy]

Also what temperature thermostat do you have?

[trackjunkie21]

you sure the low speed isn't the one that went bad? 81c is near the 1/2 mark.

Yes I'm sure, my temp guage is a little fubar'd though, I need to tighten the ground bolt

If the resistor on the fan was bad, it wouldn't kick on on low speed. If it's coming on with the AC button, thats the low/normal speed.

It sounds like it's possible that your temp is getting to 88 but maybe the high speed isn't coming on?

Have you checked the fuse/relay for the high speed fan circuit?

The fuse/relay is good, I jumped the high speed and it works

Also what temperature thermostat do you have?

It's the stock temperature one for the m50, 75* is it?

[Fusion]

Mine does the same thing.
I have 80° stat and switch, no a/c. Did this with two different radiators.
My fan has hi/lo speed and I have buttons for manual on/off of both speeds. I usually turn them on depending on my judgement, but when I forget, I noticed low kicks in a little behind the halfway mark and I haven't yet seen "automatic" high speed.
So my guess is either the gauge is off, or the temp difference is due to the gauge info sensor being in the head, whereas the switch sensor is in the radiator... so when the coolant in the rad hits 80, the fan starts, cools, and there's a delay until the cooler coolant gets to the head, then you see a temp drop (mine often drops two ticks under half). Sometimes all it takes is some revving to get the coolant moving more.

I heard that the gauges/sensors in new cars are not as sensitive so they average the temp and the coolant needle pretty much never moves once you're at operation temps. The older they get, the more sensitive they are and therefor you see them move more.
Someone correct me if this is a myth.

[jlevie]

The OE thermostats for an M50 are 88 or 92C units, but that doesn't explain why the aux fan isn't comong on with an 81/88 thermoswitch. My first guesses would be air in the cooling system, a bad thermo switch, or bad fan control relays

[trackjunkie21]

The OE thermostats for an M50 are 88 or 92C units, but that doesn't explain why the aux fan isn't comong on with an 81/88 thermoswitch. My first guesses would be air in the cooling system, a bad thermo switch, or bad fan control relays

Everything is new on this engine, new thermo switch, new relays, and I bled the cooling system and make sure there is no air ;)

[blackhawkimpact]

I have the same problem. But i think my temp gauge is shit. When I'm at a stop or a drive thru, for instance, temp rises all the way to the red or close to the red, regardless if I turn on the fan with the ac button. But once I accelerate to about 10mph, in 6 secs. it goes all the way down a bit below the 1/2 mark.

[trackjunkie21]

I have the same problem. But i think my temp gauge is shit. When I'm at a stop or a drive thru, for instance, temp rises all the way to the red or close to the red, regardless if I turn on the fan with the ac button. But once I accelerate to about 10mph, in 6 secs. it goes all the way down a bit below the 1/2 mark.

Mine does this aswell, the one important guage, and BMW fucks it up:hitler:

[trackjunkie21]

Update: I had High speed kick on today, but the needle was just ready to go into the "red zone". I used an infrared temp guage and it said the engine was at about 90* or so. That doesn't seem like overheating, is it?

[nando]

maybe your thermostat isn't working? or the temp sender/gauge is bad.

[trackjunkie21]

maybe your thermostat isn't working? or the temp sender/gauge is bad.

The guage is probably bad, Everything in the cooling system is new and both hoses get hot when the car is warmed up. Will tighten the nut on the back of the cluster this week.