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6/29/16 11:27am - Original Message: 'Temp in gauge changes erratically after warm up'
VegasVet
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las vegas, NV - USA

Vette(s):
Custom stalker kit, modified engine, new paint

Joined: 3/18/2014
Posts: 9
Temp reads from 140 to 200 then stabilizes then changes all over the place slowly then when parking here bubbling.  Haven't even opened hood its hot here in Vegas will check things this weekend. ideas about temp gauge?

|UPDATED|6/29/2016 9:27:40 AM (AZT)|/UPDATED|


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7/3/16 11:09am - Reply: 'Re: Temp in gauge changes erratically after warm up'
rtslt4
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Joined: 7/2/2013
Posts: 31
When cold, make sure the cooling system (including the heater core) is purged of all air & all parts of it are full to required levels including the coolant recovery tank.

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7/10/16 3:42pm - Reply: 'Re: Temp in gauge changes erratically after warm up'
VegasVet
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las vegas, NV - USA

Vette(s):
Custom stalker kit, modified engine, new paint

Joined: 3/18/2014
Posts: 9
just checked and there the  radiator needed a cup of coolant of course over flow tank is never full, just realized somehow the radiator cap was changed to 7 llbs  thanks for replying, more after testing

|UPDATED|7/10/2016 1:42:28 PM (AZT)|/UPDATED|


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7/11/16 8:16am - Reply: 'Re: Temp in gauge changes erratically after warm up'
rtslt4
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The specification on the radiator cap should be 15 or 17 Lbs depending upon the year & engine of your car.  Check the specification in your owners manual.  You should also ask the question why only a 7 lbs radiator cap was there in the first place.  I recommend an AC Delco or Stat replacement.

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7/11/16 7:09pm - Reply: 'Re: Temp in gauge changes erratically after warm up'
Hot Rod Roy
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Mission Viejo, CA - USA

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Yellow '84 Coupe

Joined: 3/18/2015
Posts: 38
VegasVet said:  of course over flow tank is never full, 

Why do you say "of course"?   Your coolant reservoir should be about one third full, and the radiator should be 100% full with a cool engine.   As the coolant in your engine heats up, it expands, and the excess will flow into the reservoir..   As the engine cools off, the coolant will contract, and the coolant in the reservoir will be drawn back into the radiator, thus keeping your radiator 100% full.   This presumes you have a good radiator cap!

The reservoir is not an "overflow tank".   If the reservoir becomes "full", something is wrong.   If the radiator does not stay 100% full, something is wrong.




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7/11/16 9:56pm - Reply: 'Re: Temp in gauge changes erratically after warm up'
VegasVet
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las vegas, NV - USA

Vette(s):
Custom stalker kit, modified engine, new paint

Joined: 3/18/2014
Posts: 9
That is why I said of course the reservoir is not full. I left cap off after filling and it went down a little over night no leaks and engine is new hope it was just settling. will test tomorrow

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7/12/16 6:58pm - Reply: 'Re: Temp in gauge changes erratically after warm up'
Hot Rod Roy
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Mission Viejo, CA - USA

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Yellow '84 Coupe

Joined: 3/18/2015
Posts: 38
VegasVet said:  I left cap off after filling and it went down a little over night 

Left cap off reservoir, or left cap off radiator?   What went down?   Having trouble understanding what you're trying to say.



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7/13/16 10:15am - Reply: 'Re: Temp in gauge changes erratically after warm up'
VegasVet
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las vegas, NV - USA

Vette(s):
Custom stalker kit, modified engine, new paint

Joined: 3/18/2014
Posts: 9
Left cap off radiator over night to observe and it was lower, we are repeating this and it is still lower at radiator then after testing all day it stayed at the top, put cap on and drove it seemed better however when accelerating and warmed up temp gauge would still dip 20 degrees however at  idle or at constant speed temp would stay constant, still checking or air pockets, new plan to idle with cap open at a incline so it will help purge? Waiting for cool off this morning to test level.

|UPDATED|7/13/2016 8:15:17 AM (AZT)|/UPDATED|


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7/13/16 12:50pm - Reply: 'Re: Temp in gauge changes erratically after warm up'
rtslt4
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Does your car have a bleeder screw on the thermostat housing?

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7/15/16 10:26am - Reply: 'Re: Temp in gauge changes erratically after warm up'
VegasVet
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las vegas, NV - USA

Vette(s):
Custom stalker kit, modified engine, new paint

Joined: 3/18/2014
Posts: 9
No it does not temp is OK I think temp gauge is erratic when under normal acceleration is drop substantially waiting to cool down this morning to check connection on sending unit 

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7/15/16 8:41pm - Reply: 'Re: Temp in gauge changes erratically after warm up'
Hot Rod Roy
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Mission Viejo, CA - USA

Vette(s):
Yellow '84 Coupe

Joined: 3/18/2015
Posts: 38
Are you paying attention to the coolant reservoir?   You don't say anything about this.   If you keep the radiator cap on, any bubbles in your radiator should be expelled into the reservoir as the engine heats up, and when the engine cools off, fluid should be pulled into the radiator to keep the radiator full.   That's why you need to keep the reservoir at least one third full when the engine is cool.   The reservoir should automatically have more fluid in it when the engine is warm.

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7/16/16 10:13am - Reply: 'Re: Temp in gauge changes erratically after warm up'
rtslt4
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Are you paying attention to the coolant reservoir?   You don't say anything about this.   If you keep the radiator cap on, any bubbles in your radiator should be expelled into the reservoir as the engine heats up, and when the engine cools off, fluid should be pulled into the radiator to keep the radiator full.   That's why you need to keep the reservoir at least one third full when the engine is cool.   The reservoir should automatically have more fluid in it when the engine is warm.


He is correct as stated but that is the final step.  Another trick to purging the cooling system is squeezing the upper radiator hose by hand while the engine is cold with the radiator cap open.  During this procedure, note any air bubbles coming out, topping off the radiator in the process, and taking care to minimize spillage.  This process is done when air bubbles are no longer surfacing.

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8/10/16 2:41pm - Reply: 'Re: Temp in gauge changes erratically after warm up'
VegasVet
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las vegas, NV - USA

Vette(s):
Custom stalker kit, modified engine, new paint

Joined: 3/18/2014
Posts: 9
Found the issue, connector on sensor which looked good, upon further inspection found plastic was holding wire which was barely making contact also further inspection found radiator cap had been changed to like 8 lbs so replaced with 16 lbs really holding pressure here in Vegas where it is very hot next job is to add a switch to fan relay to turn on when it hits 200 rather than wait until 225. Also found lose wire in undercarriage going to front fans.

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8/10/16 4:38pm - Reply: 'Re: Temp in gauge changes erratically after warm up'
rtslt4
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What year is your car?

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