I tested the gauge by grounding it on the frame and it goes to full hot. when I put the wire on my brand new temp sender it does absolutely nothing no matter how long I let the engine run. The temp not registering is exactly why my last motor blew so i would like for that not to happen again. I used sealing tape on it when I installed it, will that make it not work? the wire isnt grounded anywhere and it goes to cold when it isnt grounded on the frame. what am I missing here? I would really like to drive my car without fear of it blowing up on me again.

 

You tested the gauge properly so either the "sealing tape" is not letting the sender ground or the sender is bad. Try it with no tape.
Many of the senders are not accurate but BTW#WT203(Z) seems to work pretty good.

 

azguy,

Read Roger's post.
http://forums.corvetteforum.com/c3-t...e-success.html

http://forums.corvetteforum.com/c3-t...uld-share.html


Also go to Willcox's site under repair and installation

http://willcoxcorvette.com/instructi...ions_68-82.jpg

http://willcoxcorvette.com/instructi...Revised_R3.pdf

Ron

 

I was going to give that a shot too and just put some sealant from a tube on the threads. Just waiting for the engine to cool off right now. The sended is brand new from Auto zone so it better not be bad lol I suppose it does happen though. thats why I asked on here to make sure I was doing everything right before I did anything hasty

 

according to the pictures at the bottom on the wilcox page, I have no signal, with ground and power. whatever that means lol

 

I got the wt203 from orielly auto so hopefully that will work better, I will try and get it put in tomorrow or Monday. How much coolant should I expect to lose taking the sender out?

 

If the engine is cold and you have a thumb ready, you won't lose much coolant at all. Or you could have a 1/4" pipe plug ready to stick in the hole to plug it temporarily.

The ground for the temp circuit is created between the threads on the sender and the engine block. Teflon tape could act as an insulator, if you put more than one round of tape on those threads.

 

yeah I think I put 2 or 3 rounds on it. I am pulling the old one out and sticking the new one in so a plug shouldn't be needed but I will keep that idea in mind for other projects I may have to do lol. Good to know I wont lose too much if I'm quick about it. Thanks.

 

Make sure you have the right sender! The same thing happened to me. I didn't realize there were different senders. I thought they were generic, all the same. If you do a "search" on here you'll see/read all about this.

 

Someone actually tested the effect of tape. It's at the bottom of the page:

http://www.lbfun.com/warehouse/tech_...eCF-Thread.pdf

 

First thing that comes to my mind is that it's the wrong sender, it's a crap shoot at your local parts store. I would buy the correct one from one of the forum vendors, the should have an accurate sender for your year

 

if you have power and ground but no signal... this means the ohms reading is not making it to the gauge from the sending unit.

With the wire off the sending unit the gauge should read cool, with it grounded out it should read peg hot just like the pictures on the page I did.

I'm wondering about the Teflon tape you used. Teflon tape is not a sealant it is a lubricant and should only be used on the first three threads of the sending unit. It's not the Teflon tape that creates the seal but rather the lubricating properties of the tape that allow the tapered NPT pipe threads to be screwed together, which is what creates the seal. It should be used sparingly.. not in excess.

I know, in most cases the threads will cut through the tape... but from your symptoms... Deflecting gauge, new sender and all other things.. If I was a guessing man I'd say you have too much tape on the sender and it is not grounded.

If the gauge deflects both ways you can eliminate it as the issue.

I've posted the picture below to explain what each of the three faces mean.. in more detail from you're statement above. "according to the pictures at the bottom on the wilcox page, I have no signal, with ground and power. whatever that means lol"


In the picture above:

Left gauge when there is power and good ground to the gauge, but the ohms from the sending unit is not making it to the gauge.

Middle gauge is when you have power to the gauge, the ohms from the sending unit is making it to the gauge but the gauge is not grounded.*

Right gauge is when you have power to the gauge, a good ground and the ohms wire is grounded out on something. *This would imply: *You have a shorted ohms wire… (pinched on something) or *you could have a wire off the sending unit and possibly sitting on the engine to ground out. *

Willcox

 

One thing you could do... and Roger posted a thread about this a long time ago...

A flasher has aprox. 50 ohms resistance... you can test the system by hooking your sender wire to one side of the flasher and then running a wire from ground to the other side. If you have a multi-meter, test the ohm's on the flasher..

Then you have a known output to the gauge. Put the flasher in line and then match up the output of the flasher to the chart on my page. Once you have this in place turn on the key and see if the gauge is reading what the chart says. If i'm right about the flasher having 50 ohms resistance then this should put your gauge needle around the second mark.. depending on what year the car is.

Make sense? Hope so..

I'll check back later..

 

The OP knows the signal line is good as he grounded it and got full scale reading on the gauge. If he had the wrong sender, he would get the wrong temp reading on the gauge...it shouldn't be "no" reading.

P.S. Teflon tape is used as a sealant for use with pressurized air and water; used on plumbing stuff all the time. Yes, Teflon is slick and so it helps in tightening fittings up with less force, but its intended use as 'tape' is for sealing pipe fittings.

 

Well I installed the MT203 I got from Orielly and now the gauge works great. turns out the auto zone ones are not correct for my car. I tried 2 of them with the same result before reading up about the part they had at Orielly. Thank you everyone for your help, When I take the parts back to Auto Zone I will let them know about the issue and maybe they can resolve it.

 

How do you know if the sending unit is a WT203 ? I just bought a sending unit from NAPA before seeing this thread. I have not installed it yet and cannot find any numbers stamped on the unit anywhere. I was thinking about taking it back and buying another from one of the stores listed in this thread. But if anyone knows if this NAPA unit is a WT203 I won't take it back. BTW, it is the blade connection type for a '79, not the pin connector used on earlier models.

 

The one I got that did not work was a blade connector type. The box said WT203 on top of it. Go to the Orielly auto site and type WT203 in the search bar and it will pull up a picture of the one that I got that works. The brand on the box is BWD. Vendors here might sell it but I can't say for sure unless they chime in.

 

My car is a 78 and auto zone shows both types of senders as bieng compatible but I say it isnt so.

 

I checked the Orielly website for the WT203 and the picture shows the pin type connector. I guess maybe I need to go to the store and see if they have a Wt203 with the blade connector. I called the Chevy dealer and they said the oem sender is no longer available from GM. Does anyone know if the WT203 comes with a blade connector as well as with the pin connector.

 

Be careful. This is not necessarily true. If the room temperature resistance (ohms) of the sender is too high, the range of resistance from room temperature to hot may not be within the range of the gauge. Hence, it would not even register on the gauge.