The plastic radioator in my 89 RS went kablooie a couple of weeks ago. I replaced it with a new all metal 3 core radiator and also ended up replacing the waterpump. The engine did get hot when the radiator went. I do not have any oil in the water or vice versa. For some reason the electric fan is not working unless I turn on the a/c. The engine is running great and there are not any noises other than the usual stuff.

Where are the trouble spots for these fans?

Where is the sending unit located that fires the fan up with the temperature and how do you test it.?

Is there a safe way to "hot wire" this fan until I find the problem?

Thanks in advance.

John

 

Do you have dual electric fans, or a single? If you have duals, the fan comes on by design with the A/C or defrost, by way of a pressure switch. The other fan (if you have dual) comes on by way of a temp switch located in one of the heads. That switch won't do anything til about 235+ degrees. ALOT of people just hot wire the fan(s), but all I did was put a cooler temp switch in, and all works as advertised. That's really the easiest way to do it. If you have just the single fan, I'm not really sure how it works in conjunction with the A/C and/or temp. What kind of set-up do you have?

KAM

 

well an 89 RS will no doubt have a single fan setup unless changed over. the switch for the fan should be in the passenger cylinder head between # 6 and #8 cylinders. You can hotwire the fan to come just by sending power to the relay or directly to the fan itself. Just make sure you use a high enough amperage switch and big enough wire that is fused.

 

It is a single fan. I think I have bigger problems. The coolant is pressurizing around 160 degrees and blowing out of the cap. I turn the car off and it just sits there and boils over. so far I have replaced the radiator and waterpump. I guess I could try a thermostat but I think the engine has a blown head gasket or worse. The oil is clean (no water) and it is not smoking. That is what is getting me. I have no tale tale signs of trouble except the fact that it is just boiling over.

John

 

maybe you have air trapped in the system?

 

I don't have any experience with the single fan (well, I do, but it was a non stock wiring job), only the dual fan setup on tpi engines. I think the single fan works about the same as the auxillary fan on the dual fan setup though. Anyways, there should be one wire going to the temperature switch in between #6 and #8 spark plugs in the passenger side cylinder head. Try unplugging that wire and grounding it. If the fan turns on, you more than likely need to replace that temperature switch. If the fan does not turn on, the problem lies with the relay (passenger side at front of engine compartment near radiator cap?) or in the wiring. Since the fan works with the A/C turned on, I'm guessing that the relay is good though. So, my money is on the temp switch.

On another note, you should replace your thermostat and radiator cap as well. A failed thermostat can block coolant flow so that the radiator never has a chance to cool it. A failed radiator cap cannot hold enough pressure.

And a final note: If grounding the temperature switch does indeed turn your fan on, you can use that to hard wire your fan to a switch without needing to worry about a heavy gauge of the wire or high amperage switch (since it is only carrying the current needed to switch the relay).

 

similar to my fans problem,nice to have different approachs,thanx all for info,still not fixed yet,but gonna try something else

 

I will give the radiator cap and thermostat a try. I ran the car for quite some time with the cap off to purge the air from the system and the heater core. It blows hot air and the water in the radiator is hot so I am lead to believe it is not the thrmostat. I did not realize a radiator cap had that much to do with the cooling. I will give it a whirl and see what happens. The little brass pin that holds the spring and all together on the cap is tweeked.

John

 

Raising the pressure raises the boiling point of the coolant, so if the cap is bad it could very well cause the problem you describe. Also air in the system is very likely if it is not bled. You mentioned the pump, are you sure it is actually moving the water. You have something very obvious wrong. With the cap off you can look at pump operation through the cap hole. The larger of the 2 lines will have a nice healthy flow a little off idle. Just go slow, it will probably bump you in the nose.