Gauge install gone bad

[TxVic88]

Okay so I got this gauge for like $16. It came with a sender and some adapters. Today I spent a few hours setting it up and the damn thing doesn’t work.

Here is what I did:

- Installed new sending unit
- Ran coated copper wire from gauge in cockpit to the new sending unit on the intake
- Attached the ground to a panel underneat the dash
- Spliced into the power supply at the coin tray light so that the gauge would dim with the dash lights.

The new guage DOES light up, and when I dim the interior lights, the gauge dims too. However the gauge is not picking up any temp results (the needle doesn’t move).

Here are some pics.

The temp sender connected to an adapter



The temp sender installed in the manifold



The 'grounding tray' that I attached the ground to



The dimmer power source. I spliced the red wire (which came already attached to the gauge and with inline fuse) to the existing blue wire.



The gauge, with working backlight, but no working needle




Any thoughts as to why the gauge would light up but not read any temps?
How should I troubleshoot?

[sly]

light and sense are two different wires. there should be a 12v source wire as well for the gauge since it grounds through the sensor. 12V to needle to sensor grounded through engine.

If it only has a 12V line and not a specific "dimmer" line, then you'll have to run it to a 12v source (ACC or RUN source) to get it to register properly.

[TxVic88]

Oh shit, I did not have the instrux on me when I did the install (left em at work).

Now that I have the instrux in front of me, it looks like I need to run 2 more wires. One from the gauge to a ground and one from the guage to a 12V source. Does that sound right?

[sly]

the + lug to a 12V source... the - lug to ground and the S to the sensor. The top 2 wire is just the light bulb.

[TxVic88]

Thanks Slymer!

[Jon]

interesting. Mines a mechanical gauge though. its got the sending unit hardwired to the gauge, and then a + for 12v for lights and a - for ground.

The one Im having trouble with is the oil pressure gauge. No matter what I do, the plastic tube will not stay tight in the gauge or in the adapter.

[FatNasty]

Eeek, easy on the teflon thread tape. I put a little too much on once and it cracked the intake as I threaded it in. One wrap if any is all i use anymore, maybe its just my luck though. Gauge looks pretty good for the price, especially considering it came with the sender and adapters.

[TxVic88]

Last night I hooked up a ground wire from gauge to dash bracket and I temporarily hooked up a power wire from guage to constant 12V power source in the radio harness. I did one run with that setup and the gauge works!!!!!!!!!!!!!!!!!!!!!!!!!!!!

I then unhooked the 12V constant power wire and made the gauge inoperable for the time being b/c I need to find a 12V Run or Acc source not a constant hot source. Otherwise the gauge will run at all hours and itll run down the battery.

I am going to do some searching on the forum but can anyone think of an easy to reach 12V Run or Acc source? ? ?

Thanks Mangs!

FatNasty - thanks for the tip. Yea when I was removing the old temp sensor I was terrified of cracking the manifold. I used a deep socket (think it was 13/16) to fit over the old temp sensor but it didn’t want to budge. I almost called the whole thing off when the old temp sensor did not budge w/ a shorter ratchet but I decided to just nudge it with a longer breaker bar on there before giving up on the project. Thankfully it came out.

For the install of the new sensor I only torqued it to 8 or 10 foot pounds. I had not thought about the possibility of intake cracking from too much telfon tape but thats good to know.

[zoomie]

Eeek, easy on the teflon thread tape. I put a little too much on once and it cracked the intake as I threaded it in. One wrap if any is all i use anymore, maybe its just my luck though. Gauge looks pretty good for the price, especially considering it came with the sender and adapters.

x2 teflon tape is bad mmk the paste works just as well if not better

[gadget73]

Teflon tape is used as a lubricant so you can screw the fittings together tighter. The actual seal is from the tapered threads, and cranking things in too tight can crack stuff. Don't need much tape, a wrap or two is plenty. The paste serves the same purpose.


Jon: copper tube is your friend.

[P72Ford]

I would disagree that the paste is better than the tape. In my experience, a wrap or so of tape seals better.

I went through this with a heater hose fitting on my truck (rerouted the hose for the NOVI). I tried the paste, and the damn thing kept leaking. I took it apart and taped it, on a hunch, and never had another issue.

[87gtVIC]

Jon. You need to make sure that you have a ferrell over the line in between the gauge and hex nut as well as the adapter and hex nut. The ferrell is what makes the seal and seats the line where it needs to be. It basically needs to be crushed. Also boil a pot of water and throw the nylon line into it..this will uncoil it and make it easy to work with. I have had a nylon line for about a year in my car with no problems..I then sold it and upgraded to electrical..but it had nothing to do with the nylon malfunctioning.

As far as seals go..I like tape.

[87gtVIC]

Jon. You need to make sure that you have a ferrell over the line in between the gauge and hex nut as well as the adapter and hex nut. The ferrell is what makes the seal and seats the line where it needs to be. It basically needs to be crushed. Also boil a pot of water and throw the nylon line into it..this will uncoil it and make it easy to work with. I have had a nylon line for about a year in my car with no problems..I then sold it and upgraded to electrical..but it had nothing to do with the nylon malfunctioning.

As far as seals go..I like tape.