I'm sure that overheating issues have been covered extensively and rest assured that I have searched the forum. I'm new-ish to this forum, but not forums in general.

I recently acquired a '97 SE Sedan with 220k miles. I have little to no history on the car, so I'm basically starting from scratch with all the work I do on it. Look up my other threads to see things that have already been done or are in progress.

Now that I've got the engine and tranny running well enough I took it out for a drive yesterday. I went up the freeway about 20 miles round-trip, and noticed that when I pulled off the highway to turn around she started to overheat when I stopped at the stop light. The temperature gauge on the dash went from about 45% to ~99% in about 20 seconds; much to quick, and much to hot if you ask me. As soon as I started moving again it went back down to about the 45% mark and seemed fine. Basically, as long as I'm moving the temp is golden.

I wasn't running the AC really, although I did turn it on for a few minutes to see if it worked. Once I noticed the overheating I turned it back off.

Once I got home I opened up the hood and noticed that the radiator hose seemed to be suctioned out indicating some sort of negative pressure. This morning I removed the radiator cap and confirmed that there was some negative pressure in the system.



I did some searching around and found a couple things to check:

1. Make sure both cooling fans are running
2. Replace ECT

I didn't test to make sure both fans are running yet, but I did snap a couple of photos just under the distributor (where the ECT is supposed to be located). There seems to be some leaking going on there, but I'm not sure what yet. I haven't spent much time doing any diag yet as I wanted to get the forum's input before starting.




Let me know your thoughts on this, folks.
Jake

 

Jake, the oil leak around the distributor is likely the distributor "o" ring. I've replaced plenty of them for that exact reason. Easy repair. As for the cooling system, if you have a suction there, in the upper hose, the cap isn't venting. However, your over heat problem is separate from that. You'll need a new radiator cap. My guess is the fans aren't turning on. Could be the temp sender, or the fan relays in that case...or even the fuse for the fan relays....sean

 

Hey Sean,

Thanks very much for the reply.

Distributor O-Ring: Sounds like an easy enough repair
Suction in upper radiator hose: I had a feeling it was going to be the radiator cap; thanks for confirming!
Overheating:

Short of letting the car run til it gets to temp and visually looking to see if the fans turn on, are there other checks I can/should be doing? Is testing the temp sender pretty straight forward? How about testing the fan relays? And finally, can you tell me where the fan relay fuse is located? I'm sure I can find more info about doing these things, but if you have quick answers that might just be easier. ;-)

Thanks!
Jake

 

#34 is the fuse. There are also relays on the side of the fan housing so make sure you check those too. AFAIK, the temp sender is pretty easy to test, just check for the correct resistance. Should provide a ground for one of the relays when the temp is up....sean

 

The ECT sensor has nothing to do with the temperature gauge in the car and only sends the temperature to the engine computer. So do not replace it.

A quick test for the fans is to start the engine cold and turn on the a/c. Both fans should turn on.

 

One other thing to do when the engine is cold is to remove the radiator cap and make sure the radiator is filled to the top.

 

1. If both A/C condenser fan and radiator fan run with the A/C on, the fuse and both respective fan relays would be okay.

2. The temperature sender is only for the instrument gauge and does not send a ground to the relays or affect the fans.

3. Engine Coolant Temperature Switch A is a normally-open type of switch (located on the thermostat housing, where the lower radiator hose runs to). The test for this switch is to check for continuity when the switch is suppose to be closed. Switch A is suppose to close near or above 199 degrees F. When the switch closes, ground is sent to the relays, which should turn on both fans.

If you wanted to check that the wiring and relays are okay, disconnect the ECT fan switch A and jump the connector with a wire or small paper clip. With the ignition ON, both fans should run at the same time.

 

Hey John, Redbull,

Thanks for that info. I started the engine, but am having a strange issue with the RPMs that distracted me from checking the fans. Not sure if I should post that in this thread or a new one, though....

PS- John, I'm an October 10 birthday, too, oddly enough.

Jake

 

Update...

The engine issue I alluded to may be related after all. I started the engine and it started to sporadically rev between 1k-2k RPMs. I spoke with my sister (who I got the car from), and she told me that the revving doesn't happen all the time, but when it does, it stops once the car has warmed up. She then commented that the problem then becomes the overheating... :-)

Here's the video of the tach (sorry for how dark it is)...

Thanks,
Jake

 

Make sure the radiator is filled with coolant. Let us know how much you need to add (if any). You should bleed any air from the system. See this video:

www.youtube.com/watch?v=zUpXgAJ1gjU

This is the first step to correct your idle issue.