temp gauge/sender

[chris2520]

hello all, first post. i have an 84 C10 I6, I havent been able to get a reading on the temperature gauge. i know the gauge is good, i changed the sender, i made sure the engine was grounded and still the gauge is not reading correctly. the gauge barely moves above the C mark. i am stumped on what i can do, any help would be appreciated, thanks!

[Stewart G Griffin]

i can't help, but you may want to read this:

http://www.madelectrical.com/workshop/water-temp-gauge.shtml

[chris2520]

thanks for the read!

[hatzie]

On the fuel and oil pressure gauges lower resistance drives the gauge lower higher resistance drives the needle higher.

The temp gauge is just the opposite. 

C or 100 on the gauge should be around 34K ohms resistance. 
Lower resistance drives the gauge higher.  Grounding the temp sender wire will nail the gauge above H.

You probably have damage to the temp sender wire raising the resistance.
The other thing that can raise the resistance in the temp gauge circuit is teflon tape on the sender threads.

If the sender is wrong it'll make the gauge inaccurate... but not that bad.
http://forum.73-87chevytrucks.com/smforum/index.php?topic=32806.msg278594#msg278594

[bd]

Hello and welcome to the site.  For 1979 - 1990 trucks, the Cold line of the gauge represents 1,365 Ohms across the sender.  Pick up a 100-ohm resistor from a local electronics supplier.  Unplug the sender and connect the resistor between the sender wire and a clean ground.  Switch the ignition ON and the gauge needle should move to the center mark.  This will tell you whether to focus your attention on the gauge and wiring or the sender.  Did the replacement gauge have a ceramic resistor attached across two of its terminals?

[chris2520]

Hello and welcome to the site.  For 1979 - 1990 trucks, the Cold line of the gauge represents 1,365 Ohms across the sender.  Pick up a 100-ohm resistor from a local electronics supplier.  Unplug the sender and connect the resistor between the sender wire and a clean ground.  Switch the ignition ON and the gauge needle should move to the center mark.  This will tell you whether to focus your attention on the gauge and wiring or the sender.  Did the replacement gauge have a ceramic resistor attached across two of its terminals?

Yes the gauge does have a resistor going across two of its terminals. I think I will try out what you are saying. If the temp wire ends up being bad is it a special wire I would have to get or will a regular, I believe it's 18 gauge wire work?

There's no Teflon tape, I made sure.

[bd]

The 18-gauge copper wire isn't special, but the insulation is spec'd as SXL.  SXL is used because of its greater temperature and ozone tolerance than standard parts house PVC or GPT insulated wire.  If using other than SXL, it is best to shroud or insulate the wire from the adjacent exhaust manifold.

[hatzie]

The 18-gauge copper wire isn't special, but the insulation is spec'd as SXL.  SXL is used because of its greater temperature and ozone tolerance than standard parts house PVC or GPT insulated wire.  If using other than SXL, it is best to shroud or insulate the wire from the adjacent exhaust manifold.

Even when shrouded PVC wire will get brittle very quickly from the exhaust heat.  SXL is getting easier to find.  There are a couple vendors ln evilbay that sell assorted colors in small project lengths.

Sent from my SM-P605V using Tapatalk

[chris2520]

So I did the test, gauge pegged to the middle. Tried two different replacement senders one from o'reilly and one from autozone, no good, the gauge sits cold with those two. I called letric limited they said they did not have a sender for my truck. Any other suggestions on where I could get one that would be reliable?

[bd]

1984 250 L6 (Vin "D") with 3/8" x 18 NPT sender:  Delco 213-4793

[chris2520]

so i bought the delco sender recommended and it's still not giving me the correct reading. im now thinking my ground is bad. after a while it just pegs right about the C mark

[hatzie]

Check the power and ground splices to the cluster and the power and ground connections to the gauge itself. 

Check the calibration resistor isn't loose on the can too...  Unlikely but once you're that far into the cluster you might as well dot N cross all the important letters...