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81 Temp Sender



Hi All,

My temperature gauge is real slow to come up these days.
Last couple weeks , I think.
and even then, it only gets up to about 130.
I thought it was the cold weather and it just wasnt warming up fully. Today was pretty nice and it should have been up to 180 ish.

Does this sound like a sender that is going bad?
Replacing it is not hard , just dont want to do it if it is something else :)

It does move up a little, but barely.
The newest thing on the car is mufflers and I wouldnt think that i bumped anything putting those on.

similar question....

on a related note, my temp gauge works sometimes, but as of late, it doesn't want to work very often at all. do i have the same problem as ksems? if so, is the sender easy to replace? and how costly is it? when i had my power steering control valve replaced, i had them check to see why it was on the fritz, and they couldn't find out why.

any help would be appreciated, as having a working temp gauge is pretty darn important :) .
Sending Unit

Having just gone through an overheating problem with a 69 BB, I almost didn't post:). However, sometimes I just can't keep my mouth shut or, in this case, my fingers still. I would suspect the sending unit. An easy way to tell if your guage is working, but it obviously is a little, is to ground the lead that attaches to the sending unit, to the engine or manifold. Have someone watch the guage, it should "peg" it at hot. That will tell you if the guage has full range(can go further then 130). As far as cost the sending unit I just got from Chevy, was about 13.00. They are easy to change, 1 hint though, have your new one ready, and put some teflon tape on the threads, when you screw the old one out water(coolant) will start coming out of the head. Just screw the new one in and you shouldn't loose much coolant. Also, just a question, how has your heater been working, is it warm/hot as normal or is it a little cooler. If it has been a little cooler, it may be the thermostat is stuck open, better then stuck shut. This is another relativly easy and 5.00 thing to check......I hope this helps......Good luck......Steve

[Edited by ssvett on 01-25-2001 at 10:45 PM]
Temperature Gauge

Your '81,if it is the same as mine, also has an engine oil temperature gauge. If you drive 15-20 miles or so the oil temp and engine coolant should be within a few degrees of one another. If the oil is 130 or less than change the thermostat, if the oil runs up to 180-190 then your sending unit or gauge is failing. ssvet described how to test the gauge.
Most likely is your sending unit. Make sure to use Delco unit as aftermarket units can be off just a litte. Also, carefull with using teflon tape. The temp gauge is reading a resistance to ground and using to much teflon tape can mess this up. Some even recommend not using teflon tape but I did myself. Also, make sure the sending unit wire is not touching anything metal from the sending unit to the firewall. This can also change the ohms reading. I plan to insulate the wire with some plastic corrogated stuff. Then there is always the possbility that the gauge has gone bad even though this is the least likely situation. As mentioned, ground the sending unit wire and should peg to the right. My volt gauge just went bad for no reason whats so ever. Took me 10 days to figure out the gauge was bad. Also, have you ever cleaned the contacts on the printed circuit board? Over time it gets a little corrosion on the copper tabs. I cleaned mine with a pencil rubber eraser and electical cleaner. My tach was not working properly once and by simply cleaning the contact on the ciruit board it works just fine. A final thought is someone could have installed the wrong temp sending unit in the past. It is quite easy for a parts guy at the local shop to pull the wrong temp sending unit off the shelf. If that happens, the incorrect ohms is transmitted to the gauge giving an inaccurate reading. In my car, someone had installed a 1973 temp sending unit causing the gauge to read hotter by 20 degrees. I thought I had an overheat problem for the longest time. Sometimes the simplest things can be the problem but not usually.


Hi all,

Did the ground test and sure enough, gauge was okay...pegged to the right.
Changed out the sender and now all is well.
I only got up to about 160 going to work today, it was about
45 degrees outside this morning.

Thanks for the help ,

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