hey yall,  my 88 DL temp is pushing into the red. did the thermostat, water pump and timing belt while i was in there. system is now holding coolant, but still runs hot. I noticed the electric fan was never on so i jumped it to the battery and the fan runs. some research indicates the thermoswitch may be the culprit. my chilton says have the switch checked at the dealer but the kids down there dont seem to know or care what it is. my question is, how to test the thermoswitch my self, and might there be a relay or anything else preventing the fan from coming on. thanks

Welcome Catalina!

 

About the ThermoSwitch, there is a Writeup about installing Dual Electric Fans and a Slightly cooler temp ThermoSwitch, with Pictures and Guiding information that you might find useful, following this Link:

 

~► http://www.ultimatesubaru.org/forum/topic/125754-easy-guide-on-five-steps-to-twin-electric-fans-swap/

 

Beside the ThermoSwitch going Bad, also the Thermostat might got stuck and / or the Radiator might be Clogged; if you don't know how those things are, you might want to let someone to check the Thermostat and also to do a Flush on the Radiator plus pour Fresh antifreeze.

 

Kind Regards.

+1 on checking the radiator as JeZeK has mentioned above ^^^^.  Most of the older GD/DL radiators I pull out are severely restricted by now if they haven't already failed.

Edited September 9, 201411 yr by Crazyeights

Test the fan circuit by jumpering the terminal at the thermoswitch. The fan circuit is hot at all taimes and the thermoswitch provides ground. You can intercept a manul toggle switch from the terminals. 

 

I would first suggest you have an air pocket from having the cooling system apart. Be sure the thermostat is open while addign coolant, with the engine running. If your heater is cold this would be a lot of air pocket or low coolant.

+1 on the radiator also. 

I have yet to see one of mine overheat due to the fan thermostat failing.  It is critical to keep a close eye on coolant level - in both the recovery bottle, and the radiator itself.  In my experience, every time I've had one of these EA82 engines run low enough on coolant to read a little hot on the gauge, they need new head gaskets.  Sometimes immediately, sometimes a few months down the road.  What has happened is a small leak, pushes exhaust into the coolant passages.  Eventually, this pushes coolant out, overflowing the recovery bottle.  Enough cycles, and you are very low on coolant, more overheat, accelerating the leak.

 

Check your coolant level every day at least.  Every trip is safer, until you verify everything is ok.    If there is air in the radiator after a few trips, that's bad news...