68 Charger Temperature Gauge

[36 Dodge Brothers]

OK after figuring out that my stock gauge is reading about 25°F higher than the actual coolant temperature I searched the forum and found that early 68's have an incorrect range on the face plate. Did Chrysler/Dodge do anything to correct this issue? Am I stuck with this erroneous reading or can I do something about it? I did read that you can calibrate the gauge using resisters but how accurate is this method? I rather use a calibrated oil bath that will actually show the correct temperature. Does anyone know if this is possible, & if it is possible can you please share the procedure with me? Before I forget to mention this lilwendal restored my cluster a while back so I am pretty sure that he used the resister method to calibrate my gauge.

Thanks in advance,
Marco

[Dans 68]

Marco,

Is your temperature sensor transducer the original? I don't remember if you changed it when you thought you had a heating problem. What I would do is calibrate your gauge by first taking resistance readings from your temperature transducer as the temperature climbs, using an infrared measuring thermometer. Once you get the actual resistance readings versus temperature you take out the temperature gauge from the dash cluster and calibrate it to the actual measurements with a 5 volt DC source and the proper resistances. This is very accurate and the way that the factory checked/checks on the function. I have all the tools to do this. Piece of cake. 

The proper gauge overlay is available from many sources.

Dan

[mpdlawdog]

mine did the same thing...scared me to death!!  I put in a mechanical temp guage and a new sending unit to my stock guage....it works now and both are close in terms of numbers

[36 Dodge Brothers]

Marco,

Is your temperature sensor transducer the original? I don't remember if you changed it when you thought you had a heating problem. What I would do is calibrate your gauge by first taking resistance readings from your temperature transducer as the temperature climbs, using an infrared measuring thermometer. Once you get the actual resistance readings versus temperature you take out the temperature gauge from the dash cluster and calibrate it to the actual measurements with a 5 volt DC source and the proper resistances. This is very accurate and the way that the factory checked/checks on the function. I have all the tools to do this. Piece of cake. 

The proper gauge overlay is available from many sources.
Dan

Dan,

I did change the temperature sensor last week but I got the same results. OK Mr. piece of cake, when you have a chance come over my house and help me! I did see the proper overlay but I prefer the stenciled markings over stickers. I will call you this evening and drill you on your procedure.

Marco

[Dans 68]

I look forward to Le Challange.  

Dan

Edit: I'll make sure Paul is available to point out our shortcomings....

[36 Dodge Brothers]

mine did the same thing...scared me to death!!  I put in a mechanical temp guage and a new sending unit to my stock guage....it works now and both are close in terms of numbers

Thanks for your input mpdlawdog!

I currently have a mechanical gauge installed that gives me the correct temperature but it is only temporary until I figure this issue out. As for the sending unit I replaced the original one with one from O'Reilly's auto parts but I got the same results, probably made in China. What brand of sending unit did you use and do you have the part number?

Thanks,
Marco

[Dans 68]

Marco,

If you have a infrared temperature thermometer make up a temperature versus resistance plot - you can even take it out of the engine and do it on the stove with a candy thermometer. Take about 6 readings from 160 to 212 (every 10 degrees). We'll use these values to calibrate the gauge.

Dan

[mpdlawdog]

I will check when I get home....I know I got one from advance auto that was way off...I changed to this one and it is with in 5 to 10 degrees of the mechanical one....

[Dino]

OK after figuring out that my stock gauge is reading about 25°F higher than the actual coolant temperature I searched the forum and found that early 68's have an incorrect range on the face plate. Did Chrysler/Dodge do anything to correct this issue? Am I stuck with this erroneous reading or can I do something about it? I did read that you can calibrate the gauge using resisters but how accurate is this method? I rather use a calibrated oil bath that will actually show the correct temperature. Does anyone know if this is possible, & if it is possible can you please share the procedure with me? Before I forget to mention this lilwendal restored my cluster a while back so I am pretty sure that he used the resister method to calibrate my gauge.

Thanks in advance,
Marco

Calibrating a temp gauge is hit or miss but yes it can be done.  The faceplate was replaced by Chrysler in 68, you can buy the decal or buy a new gauge.

[mpdlawdog]

got it at autozone......part number is tu22.......128769.....hope it helps

[36 Dodge Brothers]

got it at autozone......part number is tu22.......128769.....hope it helps

Thanks, I will check it out.

[PocketThunder]

got it at autozone......part number is tu22.......128769.....hope it helps

Thanks, I will check it out.

Did this work?  What did you guys end up doing?

I'm having a low reading on my gauge, i bought a new sending unit, put it in and still have a low reading.  The sending unit i bought is BWD part number WT127.  Made in Mexico.

Paul

[36 Dodge Brothers]

got it at autozone......part number is tu22.......128769.....hope it helps

Thanks, I will check it out.

Did this work?  What did you guys end up doing?

I'm having a low reading on my gauge, i bought a new sending unit, put it in and still have a low reading.  The sending unit i bought is BWD part number WT127.  Made in Mexico.

Paul

Paul,

Sorry for the late reply. I actually did not do anything. I still have the mechanical gauge setup so anytime that I see the stock temp gauge reading high I take a look at the mechanical gauge and all my worries go away. Do you have the early gauge like mine or the later gauge with the correct temperature range? You just might need to calibrate your gauge. By the way the sending unit that I installed is also a BWD but I can't remember the part number, when I get home tonight I will post the part number.

Marco

[36 Dodge Brothers]

got it at autozone......part number is tu22.......128769.....hope it helps

Thanks, I will check it out.

Did this work?  What did you guys end up doing?

I'm having a low reading on my gauge, i bought a new sending unit, put it in and still have a low reading.  The sending unit i bought is BWD part number WT127.  Made in Mexico.

Paul

Paul,

Sorry for the late reply. I actually did not do anything. I still have the mechanical gauge setup so anytime that I see the stock temp gauge reading high I take a look at the mechanical gauge and all my worries go away. Do you have the early gauge like mine or the later gauge with the correct temperature range? You just might need to calibrate your gauge. By the way the sending unit that I installed is also a BWD but I can't remember the part number, when I get home tonight I will post the part number.

Marco

Paul,

I also used the same sending unit "BWD WT127".

[PocketThunder]

I also used the same sending unit "BWD WT127".

Ok thanks.  The Actron Multimeter i ordered just came in the mail today as a matter of fact.  I'm heading out to the shop to test my car now.  I'll see what i can figure out. 

Paul

[PocketThunder]

Ok, let me start with saying that i have no idea what i'm doing.  I bought the multimeter as recommended by another guy on this site.  Here it is.

[Troy]

Ok, let me start with saying that i have no idea what i'm doing.  I bought the multimeter as recommended by another guy on this site.  Here it is.

It's saying "You're number 1"! You have to take the plastic protectors off the probes if you plan on reading anything electrical.

Troy

[Dans 68]

Ok, let me start with saying that i have no idea what i'm doing.  I bought the multimeter as recommended by another guy on this site.  Here it is.

Hey, that looks like mine! Wait a minute...am I that other guy?    So, what do you want to know? Aside from what Troy recommended, of course.    I'll guide you through the break-in period....  

Dan

[PocketThunder]

I need to buy the infrared thermometer next, then i'll have $80 in tools (to diagnose a $15 gauge rebuild at autointruments).  Then i can follow thru your procedure to diagnose the exact problem with my gauge. 
Paul

[bakerhillpins]

I need to buy the infrared thermometer next, then i'll have $80 in tools (to diagnose a $15 gauge rebuild at autointruments).  Then i can follow thru your procedure to diagnose the exact problem with my gauge. 
Paul

And now we know why the costs go up on these projects.