I have a 1990 Loyale, 300k miles, beater but generally reliable car.

Its been running hot from time to time, but yesterday was running close to the red on temp gauge.

Added coolant, but noted there is a leak coming from the plastic nut located just above the drain stop cock.

Pulled that leaky nut out and found the threads and washer are shot. 

Can anyone tell me the purpose of that aperture into the radiator?

 

Can I just replace that or plug it with a similar nut, or do I need a specialized part?

 

Alos note the fan is not working.  How can I tell where the fan faiure lies?  Fan Motor? Controll Unit? Thermostat?

 

 

Believe the extra holes are for auxiliary cooling lines, such as for auto trans or oil cooler. Should be able to just plug it as far as I know. 

 

Not sure how to test the fan. Maybe run jumper wires from it to the battery to see if it runs??

 

John

Hi berto. Could you maybe post a picture of the "plastic nut" thats leaking? Are you possibly referring to the thermoswitch that threads in radiator? It's a larger brass nut with wires or connectors. When radiator temp is hot, the thermoswitch grounds out and the electric fan will come on. You could hook the fan to a battery to see if it the fan motor is still good as suggested  You can also test the thermoswitch itself if you have a multi-meter.  Also do you have a mechanical fan on the waterpump? 

Ah, well, yes I am a bit of an amateur...the plastic plug turns out to be for the AT cooling Which I do not have, therefore I seem to have coolant leaking from my radiator into the place where AT fluid is supposed to be.

Seems a new radiator is in order....checking on fans now...

berto

The thermoswitch tends to get slimed from moisture passing through the engine compartment.  Check the terminals on the switch and connector . Clean and clean before you reassemble and then test at idle before roaring out into traffic.