Question: Temperature Sender

[Vette79]

I ordered and installed this Temperature Sender: http://store.summitracing.com/partd...&N=700+4294908216+4294840140+115&autoview=sku


It was installed during my 79 Top-End Build Project. It is definitely reporting an incorrect temperature. Can anyone suggest or provide a different Temperature Sender for a 79 Vette that will be installed in AFR Cylinder Heads. Here is a link to the project if you have not seen it already: http://www.corvetteactioncenter.com/forums/showthread.php?t=103334

 

[Crimson Thunder]

Let me guess,the stock sender is too big for the AFR heads.I had the same problem with the crate motor in my car.After trying three different sending units i ended up at the Home Depot plumbing section and made an adapter.I know its a little"bubba" but you can't really see it and it solved my problem.

 

[Vette79]

Can I see a PIC? Thanks...

 

[Crimson Thunder]

Sure,I'm in the process of moving so it might take a day or two.

 

[Vette79]

Any chance to get a pic of this yet?

 

[Crimson Thunder]

My apologies for the delay.My Corvette has been stored at my dad's house while my family has been living with my in-laws(yes,imagine the horror)while my new house is being finished.I'll try to get over there this weekend and snap a picture.

 

[Vette79]

Why did you go through three different sending units? Did you experience the same problem I am having with incorrect temperature?

 

[Curtis]

I had a similar problem finding a temp sender with the correct threads to fit my heads. It seems various senders have different ohm ratings and that causes incorrect temperature indications on a guage. My local Pronto Auto Parts had a huge book that listed all the resistance values for the different sizes and shapes of senders..maybe your local parts dealer has that same cross reference material. Good luck.

 

[Vette79]

Not having any luck so far locating the ohm rating for a temperature sender for an L-48...

 

[vmrod]

I am having the same problem. I didn't like the location of the stock sending unit, so I ran the wiring to a port on my heads, right above the starter. Yep, smaller sized port. The sending unit does not have the same resistance. No one can help.

I'm thinking of taking a meter and measuring the resistance of the 2 different sending units. I believe the original one has more resistance than the newer one. If I subtract the difference, I should be able to go to Radio Shack and get a resistor or 2. Solder them in series with the sending unit and presto. It should work.

ummm...I decided to sell my car though, so not sure if I will be doing much more work on it. (Can still offer advice)

 

[Vette79]

The new one I have has a higher resistance of almost 3 ohms. I measured my original one and came up with 2.45 ohms. So, I am left with trying to find something close that is 3/8's or using an adapter to use the original one which would put it to close to the headers and throw the temp off anyway.

 

[Curtis]

The biggest problem I found was finding a sender with the correct resistance at normal engine running temperature and above.. I will go to Pronto sometime today and see if they can look up the sender I used and get you guys the part number. Do you need a 3/8 nipple or 1/4 inch or 1/2 inch threads ?

 

[vmrod]

I don't remember, but I think mine was 3/8". If they have the book open, jot down the part numbers for each size. (if the info is there) I wouldn't mind having this fixed before I sell the car.

 

[Vette79]

Curtis, thanks. I need 3/8's for a 79 L-48. I read in a different post that the 81 Temperature Sending Unit comes very close in ohms and is 3/8's: http://www.parts123.com/parts123/yb...~S2DW150SCX96234167936d~Z5Z5Z5~Z5Z5Z50000050G

 

[geekinavette]

I measured a GM temp sender once upon a time...I will see if I still have that data somewhere and post it.

The sender sitting a little closer to the header shouldn't bother the temperature reading...the actual sensor is way in the other end of the unit. Now the wire/connector to it might be a different story!

I had the same problem with a set of Edelbrock heads...just got a fitting adapter, no problem.

Just adding a resistor won't work...since these senders are NTC thermistors and have a non-linear response. You might correct for it at some point in the response curve...but the "error" will increase as the temperature moves away from that point.

Bill

 

[Curtis]

Sorry guys .. I checked Pronto yesterday and they no longer have the book we used a few years back that lists the resistance values of the temperature senders... Stupid computers replaced almost every typed page they had and this table was not included. I don't know how to help you now.. good luck.

 

[TMPJoe]

I ordered and installed this Temperature Sender: http://store.summitracing.com/partdetail.asp?autofilter=1&part=SMP%2DTS76&N=700+4294908216+4294840140+115&autoview=sku


It was installed during my 79 Top-End Build Project. It is definitely reporting an incorrect temperature. Can anyone suggest or provide a different Temperature Sender for a 79 Vette that will be installed in AFR Cylinder Heads. Here is a link to the project if you have not seen it already: http://www.corvetteactioncenter.com/forums/showthread.php?t=103334

wondering if my fluctuating temps are from the wiring or the sender.. mmm

 

[Vette79]

Since I know the ohm rating of the original sender, my plan is to locate any sender that is 3/8's with the same rating locally and see if that will work.

 

[Bill75]

Try this guy, he might be able to help. But you should be able to get it to fit with a brass reducing bushing.
I'm sure you know not to put teflon tape or pipe sealant on the threads because the case is an electrical ground.

http://www.corvetteclocks.com/page12.html

 

[Vette79]

Thanks Bill. A coupler or brass reducing fitting is not possible due to my headers. I sent an email to the site you mentioned requesting some assistance.