Its been a LONG time since I've posted here. I lost my original Cavalier about 6 years ago to a mechanic that skipped out of town in the middle of an engine rebuild (he left about 10 cars at his shop dismantled, so I don't think *I* scared him off).

Anyway, I picked up a 1987 Cavalier RS Hatchback with 47,000 miles on it (not kidding) for $1800. Automatic though :/ Can't have everything I guess.

What I'd like to know, what is the normal engine temperature for the radiator fan to come on? Is it 220 F? (this is the question)

I got out my code scanner to try out my OBD I cable on her (just got it) and hooked it up and saw it going over 200. I turned the A/C on (which forced the fan on) and it went down to 190 F.

I'm paranoid I've got a bad relay/switch and the only thing I've got on the dash is an idiot light (of which I have little faith in).

1985 Chevrolet Cavalier Sedan
2.0L I4 TBI OHV

What engine is in it?


- Your not-so-local, untrained, uncertified, backyard mechanic. But my @!#$ runs

Just guessing here, but I would be around 220. If you look for the "What Part Do I Need" thread of mine, it might be in there.

From that thread and the fact that your fan turns on with the AC, that means it isn't the relay or the fan motor itself, but a temp sensor.

I still have to figure out how to post pics so I can find out what I'm replacing on my 1.8 as there are two things with wires sticking out of the neck with the thermostat.

The temp sensor for the dashboard gauge is in the head near my distributor.

2.0 Liter I4 TBI OHV... can't believe I forgot that -.-

1985 Chevrolet Cavalier Sedan
2.0L I4 TBI OHV

2.0: When engine coolant temperature exceeds 238 degrees F, coolant temperature sensor sends a signal to ECM which controls cooling fan relay.

2.8: The electric coolant fan on this engine is totally controlled by the Electronic Control Module (ECM). The ECM will ground the coolant fan relay, which turns "ON" the fan, when the following conditions are met.

-Coolant temperature sensor signal indicating a temperature greater than 106°C (223°F).
Or
-A/C head pressure greater than 1380 kPa (200 psi).-And vehicle speed less than 70 mph.-When the cooling fan is turned "ON," it will stay "ON" for a minimum time of 30 seconds.



- Your not-so-local, untrained, uncertified, backyard mechanic. But my @!#$ runs

Ewww.... 238 F seems pretty high.

Oedwards, do you know what the redline temp is for the 2.0?

Also, Wayne, I definitely read your thread. Fiddled around with the relay after seeing the awesome picture pointing it over the driver's side wheel well. Hard to miss it with that help.

Idiot lights just make me paranoid and my code scanner doesn't keep a good connection.

I think I'm going to break down and put an instrument cluster on the plastic siding along the door. I want this one to last.

1985 Chevrolet Cavalier Sedan
2.0L I4 TBI OHV

No, I didn't see it, but I did find that the temp sensors range is 100F to 260F.


- Your not-so-local, untrained, uncertified, backyard mechanic. But my @!#$ runs

Thanks. I'm going to try to drive home without the A/C on with my code scanner hooked up (if it plays nice). If it goes above 235 I'll kick the A/C on and figure out what I'll do next.

Last Cavalier, I just pulled the relay and bridged the connection so that the fan would run when the ignition key was turned.

I'm trying to do it right, but I'll be damned if its not a royal pain in the a**


1985 Chevrolet Cavalier Sedan
2.0L I4 TBI OHV

Something related to this thread to keep in mind with the automatics. Since the ATF fluid is "cooled" through the radiator - the reverse is true during overheating - the high coolant temps can overheat the transmission fluid. I thought I'd post this, since the 1st Gens are getting into antique ages and while the J-Body Automatics are great transmissions - they are old as well - Not to mention the ancient ATF fluid flowing around in there.

While not everyone's favorite solution - I personally like having a switch mounted at the dash for the fan along with a mechanical gauge hooked up the fitting at the head - where the hottest temps should be. I find myself using it around in town during the stop - n - go and sometimes when I'm taking my time in parking lots, ect...during the hot summer months. It is neat to watch the thermostat opening and closing during the winter - as the cold coolant enters and slams the thermostat shut. The gauge almost looks as if the engine is breathing...LoL

I found this out there in Internet-land - don't know of the accuracy, but can use it as a rough guide....


150° F - The minimum operating temperature. Note: It is possible in low ambient temperatures to overcool the transmission with auxiliary oil to air coolers. Oil to water coolers in standard factory radiators will normally not overcool a transmission.

175-200° F - Normal pan oil temperature operating range.

275° F - Maximum allowable oil pan temperature for short durations during long hill climbs.

300° F - Damage occurs to internal transmission parts, including warpage of metal parts, degradation of clutches, and melting of seals. Transmission oil oxidizes, (forming varnish-like substances causing further clutch slippage and compounding heat build up) and transmission oil life is extremely short.

Just an old country boys 2 cents worth :-)



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Ok first if your OBD 1 reader is grounding correct key ON not running it should kick the fan on initial scan.Second our cars themostats are from 188* to 193 and thermostat fully open at 212* F.I am pretty certain that 220 is the fan kick on point! Now if your fan did not kick on (whether due to your so so scanner) I would not worry.However the fan is controlled by the ECM and you will have 2 sensors on your thermostat housing.1 is for engine temperature and 2 is for dumby light on dash.If your fan is not cycling on at said 220 could be a faulty thermostat or bad engine temp sensor.IF you were closer I could hook up my actron lcd big reader and it shows all the stats.Shows engine temp,oil temp fuel psi on and on.High tech it is and can actually drive with it plugged in for real time diagnostics!If your really concerned flush your system if over 3yrs old on the freeze and do hoses and thermostat.Since you said fan is jumperd and does work indicates the fan is fine.I am kinda worn out but if the fan cycles on obd check or even paper clipping to check for codes works too.If fan cycles on relay is fine.Tired and did some serious digging to find my info.

I made it home fine. I have an Actron as well, although it keeps getting an error displaying the "CODES" line on all the stats. It will return a "ERR" and then say "Operating Error". A little worried the ECM got some water on it after a rain and it leaked through the AC intake seals. Car is running fine though.

I did find out the radiator fan finally kicked on around 225 F. Whoever had the car before me had caked on a lot of that anti-corrosion goop, so much so that it wasn't making contact with the connector on the temperature switch. At least that's one problem solved. Your guys help and older forum posts provided most of the knowledge Thanks!

Now to find out why the AC system is causing condensation build up in the vents. Fun fun... but I wouldn't trade this Cavalier for a new car from a lot.


1985 Chevrolet Cavalier Sedan
2.0L I4 TBI OHV