I have a 91 945T with the old style radiator and the thermostat switch on the radiator. This works normally but I was wondering if there is a simple way to keep the electric fan on after the ignition is switched off like the electric fan in my 93 945 (non-turbo). I think this would help the engine cool down and my head gaskets last longer. (Anyone know where I can get a 3 row radiator or are the replacement aluminum/plastic Nissens radiotors better the original?)

Thanks
wagonman

My daughter's 1994 CA-spec 940 (Bosch LH2.4) triggers the fan from the ECU and from the pressure switches on the air conditioning. The ECU gets info from the coolant temperature sensor in the cyl. head and can switch the fan to low or high speed. IIRC, it has always shut off with the ignition, although the wiring diagrams show that the A/C switches could keep it running if high pressures are detected.

As for keeping your engine cooler after shutdown - I would say this simply doesn't happen. I have a 740 wagon with a 5.7litre Chev LT-1 V8 (aluminum heads, iron block). It uses a fan and shroud from a 960/S90, and a custom, all-aluminum 3-inch rad. The fan is triggered by a temperature sensor in the rad fins. I have a mechanical (Bourdon tube) temperature gauge with its sending unit screwed into the left cyl. head.

Now - to your question...after shutdown my fan sometimes runs for about one minute. While this is happening, I can watch the cyl head temperature gradually climb, because there is no coolant circulating. The radiator may be getting cooled down, but not the engine. Just hot air being blown around under the hood. After about five minutes the head temperature shows approx. 220F. The instant the engine starts, this drops quickly to the normal running (thermostat) level of about 185-190F. So my conclusion - based on these observations - is that having the fan run after shutdown does nothing for engine cooling.
--
Bob (son's 81-244GL B21F-M46, dtr's 94-940 B230FD, my 83-244DL B23F-M46, 89-745(LT1 V8), 98-S90, 77MGB and four old motorcycles)

Hey Wagonman,



IPD used to carry the all metal 3 row radiators, but they don't seem to stock those anymore. FCP Groton states on their site that Nissens used to make all metal radiators, but stopped in '06. The Nissens plastic units work fine, but the OE Blackstone radiators from Volvo seem to last the longest. Last time I checked a OE radiator from Tasca Volvo (www.tascavolvoparts.com) was about 200 bucks. You may be able to snag one of the all metal jobs from a junkyard car.


Does your car have a mechanical fan, or a primary electric fan? On my '92 740 (w/Regina), the primary electric fan can run after the ignition has been shut off. Its controlled by the thermal switch on the radiator. If your car has the mechanical fan with the auxiliary pusher fan on the front, you may be able to wire it so it can run after the ignition has been shut off. The caveat is it possibly killing the battery if the relay sticks closed. You should check out a wiring diagram to see where the fan gets its power from. Not sure if its switched with the ignition on your car or not. There was a Polish website with wiring digrams for these cars, but the links for the wiring diagrams are no longer working. Sorry.

Regards, Jon 'Uncle Olaf'