another overheater.
Le Mans Master
Joined: Aug 2009
Posts: 5,474
Likes: 16
From: Houston Texas
St. Jude Donor '10-'12-'13
John, why did they install the by-pass hose on the HP motors, if it doesn't enhance cooling?
I had to remove mine to install the thermostat switch for the SPAL fan.
I was concerned about it affecting the cooling.
My car runs plenty cool.
Advanced
Joined: Nov 2010
Posts: 54
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I have sent the gauge out 2 times for recalibration and am told it is working to specs. Could it be the sending unit? the IR reading at the top post (where the wire attaches) of the sending unit is 180?? just sitting here thinking is there a way to test the sending unit? put in in water and heat it on a stove with another gauge attached???
Tech Contributor
Joined: May 2005
Posts: 15,576
Likes: 118
From: Conroe Texas
I have sent the gauge out 2 times for recalibration and am told it is working to specs. Could it be the sending unit? the IR reading at the top post (where the wire attaches) of the sending unit is 180?? just sitting here thinking is there a way to test the sending unit? put in in water and heat it on a stove with another gauge attached???
This technical article will show you how to test the sending unit, and provide insight into testing the guage.
http://www.lbfun.com/warehouse/tech_...g%20gauges.pdf
As a quick test - if your temp gauge always pegs hot as soon as you start the car, it may be a wiring problem, as this is the same result if your temp sending wire at the temp sender, were to be touched to a ground point instead of the sender.
Another quick test - disconnect the temp gauge sending unit wire and measure the Ohms of resistance between the center post on the temp gauge sending unit, and ground. If it is very very close to 0, or 0, the sending unit is bad and internally shorted. The sending unit works by changing it's resistance as the engine heats. up. The hotter the coolant, the lower the resistance. But, it never goes to 0 unless the sending unit is bad. Even an engine operating at 180 degrees should show something in the 120-125 Ohms of resistance at the sending unit at that time.
Last edited by 62Jeff; Aug 27, 2011 at 09:38 AM.
Le Mans Master
Joined: Aug 2009
Posts: 5,474
Likes: 16
From: Houston Texas
St. Jude Donor '10-'12-'13
I have sent the gauge out 2 times for recalibration and am told it is working to specs. Could it be the sending unit? the IR reading at the top post (where the wire attaches) of the sending unit is 180?? just sitting here thinking is there a way to test the sending unit? put in in water and heat it on a stove with another gauge attached???
The sending unit is the most likely culprit. You need to buy them froma Corvette supplier. The local flap units don't cut it.
Team Owner
Joined: Oct 2000
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From: Washington Michigan
Le Mans Master
Joined: Feb 2001
Posts: 6,317
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From: Ocala FL
Ah, no, not quite the same.
The heater core is a mini radiator and cooling all the time. You just don't think it is as you are hopefully not directing hot air away from it into the cabin in the summer.
But it is still taking heat out of the coolant.
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Team Owner
Joined: Oct 2000
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From: Washington Michigan
Team Owner
Joined: Oct 2000
Posts: 38,897
Likes: 1,926
From: Washington Michigan
There's no way you'd show a 40* difference between straight water and a 50-50 mix of anti-freeze and water - you have other issues. The temp gauge can't be "calibrated" by itself - it has to be calibrated with the sending unit it's going to be used with, especially if the sending unit has been replaced.
You need to compare an I.R. gun "shot" of the upper radiator hose just above the thermostat housing vs. the temp gauge at the same time so you know what the gauge is really telling you; they're notoriously inaccurate.
You need to compare an I.R. gun "shot" of the upper radiator hose just above the thermostat housing vs. the temp gauge at the same time so you know what the gauge is really telling you; they're notoriously inaccurate.
Thread Starter
Intermediate
Joined: Aug 2011
Posts: 29
Likes: 0
From: Weyauwega Wisconsin
Just to think outside the box for a moment if you are trying different things on your cooling system and chasing your tail maybe it is scale build up that is an issue. What condition is your block and cooling system. Scale/rust will have an adverse affect on cooling and accuracy of sending units. If interested there are some nice water scale solvents that are safe for aluminum and copper that are not harmful. It might be worth doing. check the internet,automotive supply, some plumbers carry some. Just be sure it is not harmfull to soft metals and rubber products before using not all is good.
