Is there a way to calibrate a temp gauge? Recently my gauge pegged to the left and wouldn't move. I gathered from what I read on this forum that I needed a new sender. After I put in the new sender the gauge starts out below 100 degrees. After I drive for a mile or so the temp gauge slowly goes way up to 260 degrees and seems to hold there. The problem is 260 degrees is past the hot zone to te right! I did add some antifreeze because I had lost some when I replaced the sensor. I couldn't see that it was leaking out. I did a search on the forum here but did not see my exact problem. I'm thinking that if the gauge was calibrated, that would correct the situation. Can anyone help? Centervilledon

If you have a multimeter, you can check your senders output compared to what your gauge is reading. I would get another mechanical gauge to check what temp it says also.

Here is what the gauge should read at given resistance at the sender.

Thanx Mike for the ideas unfortunately I don't know that much about reading ohms and I wouldn't know what kind of gauge to buy or how to hook it up. I can read volts and amps but that is about it. I did find another way to calibrate a temp gauge doing searches on this forum. See what you think. You just pull the needle off the temp gauge, then idle the car til the fan kicks on and stick the gauge needle back on to point to 225 degrees. Thats when the fan is supposed to kick on. Think that will get me close enough? Don

That'll work too, but the fan comes on at 235*F.

Thanx Bloozberry, I shall give it a go tomorrow. It would be nice if that works. If it does I'm going to see if I can find out how to fix my oil pressure gauge which has never worked since I have had the car. Don

I would still be worried what the actual temp of the engine is. It sounds like the gauge is using a full sweep of the needle so it seems the temp is really going up, or something is wrong with the gauge/sender. If you have a multimeter we can probably talk you through testing the sender.

Per Ogre's Cave:
Radiator fan for 84-86 4 cylinder and all V6 comes on at 235F (with a 2-speed fan on some 84-86 applications, fan on at 221F and high speed at 241F).

Radiator fan for 87-88 4-cylinder comes on at 225F.

It seems my typical heavy handed, over zealous nature has surfaced again. I tried to pull off the temp gauge needle off and the orange part snapped off! UHG! Now what? The only thing I can think of is to hot glue a homemade needle onto the little black disk the orange needle was attached to. Help! Any ideas? Centervilledon

probably easier to just get a new gauge from a scrap yard and replace it if it still reads high then your temps probably really are high. Testing it with a multimeter is definitely the best way.

Can I get an ohm readiing by taking off the sensor connector at the block and check it there after I set my analog gauge to the ohm setting? Centervilledon

you know, after i did some reg. maintaintance, i almost overheated my Trans Am cuz i did not "burp" the system. had an air bubble or what ever and it almost blew. only took a few minutes. i break 'em -not make 'em... so i am not a engine guy but i learned something that day.
i have the same gauge problem. i was thinking about just getting a New Auto zome electric replacement. would that work?? the kit says it has multi- adapters. i'll just stick it on the windshield, low with tape. good luck, centervilleD.
later
dan

P.s. have you seen this.
http://www.fierosails.com/tempgage.html

i cannot get the stupid wires out of the metal ends to add the wire for the dash 11/13 swap.
this is supposed to be the fix for our problem.*disclaim* i think....i read the same stuff you did.hopefully.

[This message has been edited by batousai666 (edited 05-07-2010).]

For some reason I couldn't picture which wires to trade. I now get it I made a hard wire tool to remove the wires. It looks like a thin allen wrench. But unfortunately I'm with you, I couldn't get the wires out either. I guess we could cut each wire and splice in a jumper to go to the other side It wouldn't be easy but at least that is a possibility. .But now I have another problem in as much as my radiator fan doesn't kick on. I'm going to try to rig up a way to test the motor by hooking two sharpened nails to wires and to a 12 volt battery. Then just poke a hole in each wire to power up the motor directly. I wonder if that could do harm? Centervilledon

I would think that if the fan works, the relay works... Look into the fan switch on the block..

I found a temperature radiator "cap" for the front radiator. It's a 16 pound though our cars require 15. But then when you buy a new one say at Autozone, they sell you a 16.. I found the temp cap at Pepboys. If anything, it'll raise the boiling point but I don't think it'll damage the radiator.

What do you guys think.. 16 okay?

16 is fine if radiator, etc, is good. see cave, rad fail

temp gage fix... another fix. http://www.michiganfieroclub.com/Tech_Tips.html bottom of page
I did it years ago and did it in a hour during lunch at work.

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave (It's also at the top of every forum page...)

[This message has been edited by theogre (edited 05-08-2010).]

I have a similar problem which is probably resolved now, at least in my mind.

Original sending unit did not function, read 100 degrees cold and about 120 when car was fully warmed up.

Replacement sender would climb from 100 to red zone and beyond. I knew car was not really that hot though. Probably crappy chinese junk sending unit, do they do any QC at all over there?

A second replacement unit reads closer to reality, but still fluctuating between 220 and 260, more chinese crap I assume, certainly proves the first (identical brand) unit was a piece of crap. I've checked the thermostat in a pot of boiling water, it is fully open at 212 degrees.

I have a third sending unit, not sure why, don't remember ordering it but I've got it nonetheless. Just for shits and grins I might put it in and see what it does. I've bought all 3 of these from TFS, anybody have any recommendations for another source? I'm going to check out Rock Auto and see what they've got.

RockAuto has AC Delco under the Coolant Temp Sensor, at the bottom of the listed parts. It's actually the Coolant Temp Sender although it's listed with the Sensors. If you look under Sender it only has 2 brands.

ACDELCO Part # 21371 More Info {#25036809}
SENSOR,ENG Coolant Temperature Gauge 2 BLADE TERM-3/8-18 THD-STAMPED 120.5CM12V

$30.99

quote Originally posted by batousai666: you know, after i did some reg. maintaintance, i almost overheated my Trans Am cuz i did not "burp" the system. had an air bubble or what ever and it almost blew. only took a few minutes. i break 'em -not make 'em... so i am not a engine guy but i learned something that day. i have the same gauge problem. i was thinking about just getting a New Auto zome electric replacement. would that work?? the kit says it has multi- adapters. i'll just stick it on the windshield, low with tape. good luck, centervilleD. later dan P.s. have you seen this. http://www.fierosails.com/tempgage.html i cannot get the stupid wires out of the metal ends to add the wire for the dash 11/13 swap. this is supposed to be the fix for our problem.*disclaim* i think....i read the same stuff you did.hopefully.

The wirres stay in the metal ends - the metal ends pull out of the plastic shell of the connector after you depress the little metal tang that holds them in. Then restraighten the tang and insert the wire with the metal end still on it in the hole you just took the other wire out of. Then do the same with the other wire, and then plug it back onto the dash

Hmmm, why didn't I think of that! You're right, first I should see if the gage reads right for whatever resistance value is applied, then we can see what the sender does.

That said, my assumption is that I can buy a sender and the damn thing will have been verified by the manufacturer as part of a quality assurance procedure. At a minimum I would think it would be checked in an ice bath and at the boiling point before it is shipped, obviously the first unit was not or it would have been flagged for rejection! The second one may or may not be accurate.

And I have mis-stated the facts, these senders from The Fiero Store are made in the USA under the Standard brand (Standard Motor Products Inc. 37-18 Northern Blvd, Long Island NY 11101). So it's good old American crap, not Chinese crap!

If I come across as anal about this it's because I've worked in manufacturing my whole career and I understand what should be done to ensure a quality product is made, so things like this drive me nuts. That said, I also understand that sometimes bad product gets out the door no matter how robust manufacturing processes are or how good quality systems are, I can accept that I have one bad sender, possibly having 2 is unacceptable to me.

I am going to see if I can find this company online and contact them, I would like to know how these are tested and what the accuracy of them is just for curiosity. I will also get some resistors and see what my gage is doing, I'll post what I find out in either case.

My situation is not as good. My temp gauge went all the way left. After I put in a new sender, the needle would end up going over to about 240 degrees and pretty much settle in after the motor warmed up. I read that some people, as a way to recalibrate the temp gauge, pulled off their temp needle and stuck it back on to and point it where it should be pointing. When I tried the needle broke off. I made a light weight needle and painted it orange and stuck it on pointing to about 210 after it was warmed up. That's where it used to point when it worked. No luck. The needle starts in the normal position just left of 100 degrees but after it warms up to normal operating temp the needle goes past the highest mark to the right of the red area and settles there. To make matters worst when I hit the dash the needle moves back toward the middle a little each time I hit it . It looks like I need a new gauge which I gather are quite expensive. Any opinions? Centervilledon

Bought mine used from the Fiero Factory. Good price and guaranteed to work. I bet you could find one in the mall too.