Crazy overheat problem Help
Thread Starter
4th Gear
Joined: May 2009
Posts: 4
Likes: 0
Crazy overheat problem Help
97 C5 z51 package 178K miles.
First start and run with no problem, then I shut it off to go into a store, and come out and start it again and it spikes the temp gauage, if I rev it it will come back down to normal 190 deg. but this can start bouncing back and forth. It spikes, then I rev it and it come back down, then this repeats sometimes 30 times or sometimes 5 times, then after I go thur the cycles it runs fine, and clears out.
does this sound like a water pump? or computer.
I have changed thermostat, temp sensor.
Help please
Thanks
First start and run with no problem, then I shut it off to go into a store, and come out and start it again and it spikes the temp gauage, if I rev it it will come back down to normal 190 deg. but this can start bouncing back and forth. It spikes, then I rev it and it come back down, then this repeats sometimes 30 times or sometimes 5 times, then after I go thur the cycles it runs fine, and clears out.
does this sound like a water pump? or computer.
I have changed thermostat, temp sensor.
Help please
Thanks
Tech Contributor
Joined: Jan 2007
Posts: 19,567
Likes: 1,209
From: Dyer, IN
97 C5 z51 package 178K miles.
First start and run with no problem, then I shut it off to go into a store, and come out and start it again and it spikes the temp gauage, if I rev it it will come back down to normal 190 deg. but this can start bouncing back and forth. It spikes, then I rev it and it come back down, then this repeats sometimes 30 times or sometimes 5 times, then after I go thur the cycles it runs fine, and clears out.
does this sound like a water pump? or computer.
I have changed thermostat, temp sensor.
Help please
Thanks
First start and run with no problem, then I shut it off to go into a store, and come out and start it again and it spikes the temp gauage, if I rev it it will come back down to normal 190 deg. but this can start bouncing back and forth. It spikes, then I rev it and it come back down, then this repeats sometimes 30 times or sometimes 5 times, then after I go thur the cycles it runs fine, and clears out.
does this sound like a water pump? or computer.
I have changed thermostat, temp sensor.
Help please
Thanks
Is the engine running hot? Overheating? Fans running? Coolant level? Codes?
Thread Starter
4th Gear
Joined: May 2009
Posts: 4
Likes: 0
It runs 190 then spikes and stays spiked until I rev the engine or run in a high rpm range like 4500rpm in 2nd gear.
I don't don't think the engine is getting hot, if it pegs and I don't rev the engine, it puts it in safe mode and the car barley moves.
My guess is when I rev it, that moves more water around.
seams like a air pocket or something.
I don't don't think the engine is getting hot, if it pegs and I don't rev the engine, it puts it in safe mode and the car barley moves.
My guess is when I rev it, that moves more water around.
seams like a air pocket or something.
Instructor
Joined: Jul 2005
Posts: 236
Likes: 0
From: CT
If it is air pockets, Manual says to:
Fill system to base of the neck of the radiator surge tank, Start engine, idle for one minute with surge tank cap removed. then put on radiator surge tank cap. Cycle RPM from idle to 3000 rpm in 30 second intervals until engine coolant reaches 210 degrees. Shut off engine. Then allow coolant to cool until you are able to remove the surge tank cap. Then start engine again, idle for one minute and fill surge tank to 1/2" above cold full mark. Install the surge tank cap and cycle RPM from idle to 3000 RPM in 30 second intervals until coolant reaches 210 degrees. Shut off engine and when you are able to remove surge cap after engine cools down, top off the coolant 1/2" above the Full Cold mark.
That should get out any air pockets. But it almost sounds like a water pump. But did you check the tension on your serpentine belt?
hope this helps
Fill system to base of the neck of the radiator surge tank, Start engine, idle for one minute with surge tank cap removed. then put on radiator surge tank cap. Cycle RPM from idle to 3000 rpm in 30 second intervals until engine coolant reaches 210 degrees. Shut off engine. Then allow coolant to cool until you are able to remove the surge tank cap. Then start engine again, idle for one minute and fill surge tank to 1/2" above cold full mark. Install the surge tank cap and cycle RPM from idle to 3000 RPM in 30 second intervals until coolant reaches 210 degrees. Shut off engine and when you are able to remove surge cap after engine cools down, top off the coolant 1/2" above the Full Cold mark.
That should get out any air pockets. But it almost sounds like a water pump. But did you check the tension on your serpentine belt?
hope this helps
Tech Contributor
Joined: Jan 2007
Posts: 19,567
Likes: 1,209
From: Dyer, IN
It runs 190 then spikes and stays spiked until I rev the engine or run in a high rpm range like 4500rpm in 2nd gear.
I don't don't think the engine is getting hot, if it pegs and I don't rev the engine, it puts it in safe mode and the car barley moves.
My guess is when I rev it, that moves more water around.
seams like a air pocket or something.
I don't don't think the engine is getting hot, if it pegs and I don't rev the engine, it puts it in safe mode and the car barley moves.
My guess is when I rev it, that moves more water around.
seams like a air pocket or something.
I'm not qualified to pull teeth......good luck...
Thread Starter
4th Gear
Joined: May 2009
Posts: 4
Likes: 0
The guage spikes very very fast, like bamb. then I rev it and it drops back down, the digital guage matches unitl it spikes then it just says coolant to high.
Again if I rev it up to red line it goes back to normal but sometimes I have to rev it 10 times and it regulates then others it keeps going and won't stop.
Not sure on codes,I don't think it is really running hot, but not sure.
Why would it not do it when I first start for the day and drive it?
It only happens once I have driven it turned it off then start it and drive again.
Again if I rev it up to red line it goes back to normal but sometimes I have to rev it 10 times and it regulates then others it keeps going and won't stop.
Not sure on codes,I don't think it is really running hot, but not sure.
Why would it not do it when I first start for the day and drive it?
It only happens once I have driven it turned it off then start it and drive again.
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Tech Contributor
Joined: Oct 1999
Posts: 41,066
Likes: 9,835
From: Charlotte, NC (formerly Endicott, NY)
Your description is somewhat confusing. However, engine temperature doesn't change as quickly as you say the gauge is changing. Even if the thermostat was sticking the transition from normal temp to overheat would take a good number of seconds. I would suspect an air bubble or an electrical problem with the sensor, its wiring/connectors or the PCM and its connections to the coolant sensor harness. The PCM reads engine temperature as a varying voltage which could be affected by a poor connection. When the temp spikes something is causing a problem in the connection and when you rev the engine you torque it over just enough to eliminate the wiring problem.
Also check the battery to see if there any problems with it, its connections to the PCM or its ground.
Bill
Also check the battery to see if there any problems with it, its connections to the PCM or its ground.
Bill
Last edited by Bill Dearborn; May 7, 2009 at 06:31 PM.
Tech Contributor
Joined: Dec 2006
Posts: 10,962
Likes: 29
From: Van Buren Arkansas
Wounded Warrior Escort '11
Your description is somewhat confusing. However, engine temperature doesn't change as quickly as you say the gauge is changing. Even if the thermostat was sticking the transition from normal temp to overheat would take a good number of seconds. I would suspect an air bubble or an electrical problem with the sensor, its wiring/connectors or the PCM and its connections to the coolant sensor harness. The PCM reads engine temperature as a varying voltage which could be affected by a poor connection. When the temp spikes something is causing a problem in the connection and when you rev the engine you torque it over just enough to eliminate the wiring problem.
Also check the battery to see if there any problems with it, its connections to the PCM or its ground.
Bill
Also check the battery to see if there any problems with it, its connections to the PCM or its ground.
Bill
Either and air pocket or bad coolant temp sensor. The sensor is a seriously important one too. The PCM relies on that sensor to determine lots of settings for the fuel and iginition.
Thread Starter
4th Gear
Joined: May 2009
Posts: 4
Likes: 0
I am leaning toward a electrical problem, I have trouble with the A/C blower staying on all the time, so I have the fuse pulled.
also the side supports in the seat go in and out on there own.
Gas guage some times just reads empty.
Let me know what you think
Thanks
also the side supports in the seat go in and out on there own.
Gas guage some times just reads empty.
Let me know what you think
Thanks
