71 temp guage
Thread Starter
Burning Brakes
Joined: Apr 1999
Posts: 797
Likes: 1
From: EUNICE, La
71 temp guage
Changed cyl heads on my 350. Had to move the original temp sender to the intake and extend the temp wire about 16 inches. Now guage reads just above 100 when warm. Checked engine with IR gun and it's at 180-190 degrees. So did extending the temp wire mess up the guage reading?
Guage read fine and accurate before!!
Guage read fine and accurate before!!
Team Owner
Joined: Jul 2006
Posts: 22,150
Likes: 4,165
From: Kannapolis NC
Changed cyl heads on my 350. Had to move the original temp sender to the intake and extend the temp wire about 16 inches. Now guage reads just above 100 when warm. Checked engine with IR gun and it's at 180-190 degrees. So did extending the temp wire mess up the guage reading?
Guage read fine and accurate before!!
Guage read fine and accurate before!!
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,116
From: Crossville TN
The electrical 'ground' connection for the temp gauge circuit is between the threads on the sending unit and the threads in the cylinder head. If you used sealant or teflon tape on those threads, that's likely your problem.
If you need to seal any minor leakage, use a pipe fitting paste sealant. That will not inhibit electrical connection between meshing threads on that sending unit.
If you need to seal any minor leakage, use a pipe fitting paste sealant. That will not inhibit electrical connection between meshing threads on that sending unit.
Last edited by 7T1vette; Feb 1, 2016 at 11:49 AM.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,116
From: Crossville TN
Before you go 'messing' with it, just get a piece of wire to act as a "jumper" and, while the car is at operating temp (engine could be OFF, but ignition ON), touch one end of the wire to the sender body and the other end to a good ground point. If the threaded joint is the problem, the temp gauge should then show the correct engine temperature. If it still reads the same, that threaded connection is not the problem.
If you changed the sending unit, it could be a different calibration. Various model years used different sender units [with differing calibrations]. If this could be your problem, Willcox has support videos on how to recalibrate your temp gauge. This is done without having to dig into the gauge cluster area.
Wish you luck!
If you changed the sending unit, it could be a different calibration. Various model years used different sender units [with differing calibrations]. If this could be your problem, Willcox has support videos on how to recalibrate your temp gauge. This is done without having to dig into the gauge cluster area.
Wish you luck!
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Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,116
From: Crossville TN
It is possible that you didn't get the total amount of coolant back in the system. The best way to fill the system is to remove the radiator cap and fill to required level. Then, with cap still removed, fire engine and allow to reach temp where the upper radiator hose begins to get hot. This means that the thermostat has opened.
When the stat opens, the fluid level in the radiator will usually drop some more, as air trapped behind the stat is released. If it drops, refill to the required level again, then install radiator cap.
No...with the cap off, it will NOT blow out hot water.
Try that. If you have to add much water/coolant, that may have been your problem. It is highly doubtful that anything in the gauge cluster area is at fault. The sending unit (just removing it could have damaged a very old sending unit) and wiring back to the firewall are MUCH more likely to be at fault.
When the stat opens, the fluid level in the radiator will usually drop some more, as air trapped behind the stat is released. If it drops, refill to the required level again, then install radiator cap.
No...with the cap off, it will NOT blow out hot water.
Try that. If you have to add much water/coolant, that may have been your problem. It is highly doubtful that anything in the gauge cluster area is at fault. The sending unit (just removing it could have damaged a very old sending unit) and wiring back to the firewall are MUCH more likely to be at fault.
Team Owner
Joined: Jul 2006
Posts: 22,150
Likes: 4,165
From: Kannapolis NC
Just a rough reading, with engine at 180, the top of the sender should read around 120 ohms with an ohmeter to ground.
Last edited by 65GGvert; Feb 2, 2016 at 08:39 PM.