Chevy 350 high idle

My question is what could cause a high idle?
I have a 95 Chevy pickup 4x4 with a 5.7
Recently the lower radiator hose fell came off the radiator, dumping the liquids all over the street.
The motor shut down, and everytime we went to start it there would be a loud whining/spinning noise.
We thought that the motor seized, so we pulled the plugs, turned the motor by the crank bolt.
Turned out that the starter went bad, the spindle and bendex werent catching on the flywheel. After examining the flywheel teeth, and gapping the plugs to the recommended manufacture gap, (they werent when we pulled them), we got a new starter installed. It started right up! But it ran at a high idle, around 1500-2000 RPM. I did not have a chance to really let it warm up (it was cold and raining). Now there is a gray flexhose that is running from the air filter housing down to the exhaust manifold. If i remember correctly, it was not seated very well when I took it off. Could it be causing too much of a vacuum?

Did the engine overheat when the coolant was lost?

If so, what can happen is coolant temperature sensors can be damaged from this overheating. So if the engine overheated it may have damaged the coolant temperature sensor for the computer. So now the sensor is telling the computer the coolant temperature is at -20 degrees. And that will cause the idle to be very high.


It did overheat. It actually shut off when it happenened. Would it affect it while in park and neutral? Or would that happen while its in gear as well? The truck only idles when it’s not in gear.

Tbi 350. Have you inspected throttle linkage? 1500-2000 is high but you know that. Why a starter died when you dumped coolant is odd. Issues are not related

If anything the throttle cable is loose I was able to throttle it by hand so it’s not stuck. I did notice one thing today though. When the AC is on the AC compressor will occasionally click and the plate on the front of the pulley will stop spinning, then click again and start spinning. This does not change the idle speed though. As to why the starter failed, I’m not sure it may have been a coincidence, I mean it happened at the same time. The engine got hot, shut off, and then when we went to start it back up the starter made that tell tale spinning noise.

A/c clutch plate is engaging/disengaging. Just set hvac to vent or off while u fiddle with idle. A/c on will raise idle a few hundred rpm at most. Is there an a/c plunger that extends to adjust throttle stop?

So I decided to drive it to warm it up a little and see if I was still having an overheating issue. The temp gauge is not working now. Could that be a side effect of the engine temp sensor?
Also there is no a/c plunger to adjust the throttle, there is the idle cable adjuster and there is the throttle cable connected to the pedal, thats all that I saw.
Heres a couple of pics I took if it helps

If the temp gauge doesn’t work, then coolant temperature sender for the gauge was damaged when the engine overheated. If the sending unit for the gauge was damaged, the coolant temperature sensor for the computer may have also been damaged causing the high idle.


OK so if I replace the sensor and sending unit would it be wise to replace the gauge sensor? What about the thermostat? Should that be replaced also while im in there?

The sending unit is for the gauge. The sensor is for the computer. And I would replace both.

Thermostats can also be damaged from overheating. But I would wait and drive the vehicle to see if there’s a possible problem with the thermostat. Such as overheating or the coolant doesn’t get up to normal temperature.