Running Hot - Fast Idle

[87BrownToy]

Ok, here's the rundown...
1st symptom...
For quite a while my '87 (4AC) Corolla has been running at the 3/4 or higher temp range. It does cool on the highway, but still above midrange. To make it really weird the temp guage quickly moves to HOT whenever I turn on the High Beam headlights or use a turn signal. ??????

2nd symptom...
Just today the car started idling really high (no tach, but it's too high). It has been running beautiful until today and I've checked vacuum lines and carb linkage.

In reading many of the threads on the forum, I see that the temp sensor could cause this, which is why I've included both problems, but the guage isn't reading cold.

Any ideas???

[REN69]

replace the thermostat.. that will probably work.. if it still keeps doing it, then yeah the temp sensor is probably gone.

[1985rollasr5]

sometimes if u let the car run till it starts to get warm and turn it off and put a glove on and grab the hose that comes from the thermostat and clap it with ur hands and if u hear the water then its not the thermostat that way u dont have to go buy one but they are only 5 or 10 bucks but dont burn urself

[87BrownToy]

Idle Speed ???
Thanks for the tips...

I'm going to check out the water temp, but I'm more concerned with how it decided to start idling so fast in a ten minute span of time.

I mean it was normal when I left for work yesterday, and when I got to work and parked, it was idling way above normal and has been that way ever since.

Until then there was a very smooth idle (I have a new carb, rebuilt head, and new vacuum lines as of 3yrs ago)and there was no significant change in idle speed when it was in Park or Drive. Now it almost races in Park and drops considerably when it's shifted to drive/reverse, but it's still higher than normal.

Tonight I did a compression check on all 4 cyl, just to make sure the worst hadn't happened. I've quadruple checked all the vacuum lines and the carb linkage. Throtle cable is fine.

I think I'm going to get a diagnostic check for a bad sensor or something ?????

[87BrownToy]

First- I'm not having the idle problem anymore. I think it may have been a bad tank of gas?????? I had just filled up the day before it started acting weird and then it got better when I was down to fumes again in the tank. It's been fine for a couple days now.

OVERHEATING PROBLEM --- I replaced the thermostat and it's still heating up too much. I wonder if the radiator is a little plugged up.

[Flashmn]

To make it really weird the temp guage quickly moves to HOT whenever I turn on the High Beam headlights or use a turn signal

Sounds like a grounding problem in the gauge cluster.

[87BrownToy]

Ya know, after the last thread it just occurred to me that the High Beam indicator light and the direction indicator lights do seem to flicker when used.

I was assuming some sort of short in the fuse box or wiring, but it makes more sense that it could be something in the cluster itself.

Thanks, I'll check that out and get back.