cluster tells I'm overheating before electric fan switches on

[raudonis]

Can the engine start overheating before rad coolant reaches 82° to activate the temp switch? Cluster tells me engine is overheating before the fan switches on.

Have installed a 16" SPAL puller instead of the clutch fan. It is switched by the 82/72° switch screwed in the top of the radiator. New rad, new hoses, new thermostat, new coolant, new waterpump, new temp sensor for the cluster.

Wiring is good, fan turns on if i jump the wires connected to the temp switch.

Tried two different new temp switches, both activate ~82° in a glass of boiling water with a cooking thermometer. And 82° is really too hot to touch the glass.

I know thermostat opening is good, because engine gets pretty warm, before bottom rad hose starts suddenly getting hot.

Warm coolant is getting to the rad, but judging by the touch it doesn't seem to get nowhere close to 82° before my cluster is telling me that engine is overheating.

If I put the HVAC blower on full hot blast and jump the temp switch wires to turn on the fan, the engine cools down to the point of thermostat closing - bottom rad hose gets cold. My cluster is toasted?

[jlevie]

As far as I know the only thermo switch used on any E30 was a 91/99C unit. So I have no idea what you have.

If you have replaced the engine fan you need to use a single 82-83C thermoswitch to control the fan. You can connect that to the high speed relay, but it is better to use an SPAL relay kit to control the fan. And you need the fan to be rated for at least 2000CFM to equal the engine driven fan. In warmer climates that can see ambients of 32C or more you need a 2300-2400CFM fan.

[raudonis]

I have 82/72° switch that everyone else is using for E-fan conversion.
Wiring and relays are good, because fan is activated if I jump the two wires connected to the temp switch.

Looking for temperature/impedance graph for the cluster temp sensor to track engine temp using Ohmmeter. Sensor # 62110788115.
About to try Si-board delete: http://static.flickr.com/106/294049943_805192b84d_o.jpg

[raudonis]

Reading about e-fan conversion for teh mighty Euro S50, got another idea about my problem.

All factory BMW rads have AC-fan switch holes on the cool side of the rad (above bottom hose).

Thermostat is 80°, thus temp switch for the fan must be no more than 80° and mine is 82°.

Found 3 other switches to try with the same thread and wiring contacts:

FAE 36310 (Rover OE # PEJ 10006) 77°-72°
EPS 1.850.142 (Facet 7.5142 or Volvo OE # 3211204-7) 72°-67°

[Nutzy]

Get a laser temp gun and measure some shit. They're pretty cheap now. Cluster might be telling porky pies.

[raudonis]

Problem solved:

I'm using large earlier type rad (from eta).
There are two slots for fan switches in the upper driver side corner.
Following the logic that higher mounted switch will get hotter sooner I was using the upper slot all this time.
It turns out this upper slot more or less sits in an air pocket and barely gets any direct coolant contact.
I've moved fan switch to the lower slot and it is finally working as intended :)