water temp guage not working

[cobras]

ok i just took it out for a drive today and it was great now i have a problem with my temp guage not working, oil temp guage works, and the fans come on automaticly but no reading on the water temp guage, i know the sending unit is on the intake manifold, but what steps do i take to figure out if its the guage or the sending unit, damm the car only has 700 miles on it and already with this
i was under the dash fixing the speedo bouncing issue so i will double check i didnt touch anything under there.

any imput would be great on this, someone who had the same problem what step to take what/ where to check

thanks again

[patrickt]

1) With the engine running and the coolant warm, rap sharply on the gauge with your knuckle and see if the needle was stuck.

2) If your gauge is electrical, make sure you're getting 12v to the gauge (using a VOM). If you are, double check your connections and then disconnect the sending wire from the sending unit on the IM and ground it and see if your gauge moves. If it does, then that sender is bad. You can also check your sending unit with a VOM if you have a mind to.

3) If your gauge is mechanical, and you can't fix it with a knuckle rap, then you're going to have to replace it.

Personally, I've had great success with the knuckle rap on my mechanical Smiths. But I wouldn't bother replacing the gauge until Spring, sometimes they fix themselves if left alone for a while.

[Ronbo]

The sending unit is merly a resistive element that changes value based on tempature.

With this in mind disconnect the lead to the unit and briefly short it to ground. This should cause the gauge to swing. You can also test this at the gauge's sender terminal itself with a jumper wire to ground (disconnect existing wire first).

I've seen sending units with both coefficiants (either raise or lower resistance with temp increase) so I can't tell you which to look for.

You'll want to verify +12v to the gauge's IGN terminal as well as GND connection.

Oops, looks like Patrick beat me to it...

[cobras]

Originally Posted by Ronbo

The sending unit is merly a resistive element that changes value based on tempature.

With this in mind disconnect the lead to the unit and briefly short it to ground. This should cause the gauge to swing. You can also test this at the gauge's sender terminal itself with a jumper wire to ground (disconnect existing wire first).

I've seen sending units with both coefficiants (either raise or lower resistance with temp increase) so I can't tell you which to look for.

You'll want to verify +12v to the gauge's IGN terminal as well as GND connection.

Oops, looks like Patrick beat me to it...

woah that all sounds like french to me, hahaha well i will try the knuckle test first since its all i understand at the moment, any chance you can put that in ... how to check your water temp guage for dummies. cause im not following you on that.

[Blas]

The water and oil temp gauges use a "Bulb" and tube filled with a gas to transmit temperature back to the gauge. Bending the brass tube to a tight radius can kink the tube and cause a leak. Your water temperature sensor is most likely in the front of the intake manifold on the top. It's surrounded by sparkplug wires most likely...if you were to have a spark jump from a wire to the brass tube, it will cause a small hole and the gas will leak out. Sometimes the gauge just reads low for a few days, and then dies, sometimes, it just dies straight off. The cheapest ans easiest way to remedy this is to replace the gauge. Yes, it can be fixed. but from a time and cost point of view, just replace it. Replacement is very simple; with a cold engine, you can just remove the bulb sensor end and not need to drain the cooling system. Don't loose the brass washer at the manifold connection. Use large radius bends in the brass tube when replacing the entire assembly. Everyone will replace these gauges in time. I've done one of each so far....old, period correct technology at it's finest...welcome to the wonderful world of Cobra Ownership...But jobs like this are how you learn about your car and how to work on it....enjoy !!!

[MEvang]

Blas is correct. But I have just recently been in contact with Nisonger and they will warranty Smith gauges for two years from the date tag on the side of the gauge. (As long as it can be read) You will need to send the gauge into to Nisonger (they advertise on this site) or a Superformance Dealer for repairs.
If you need details IM me.
I haven't gotten a billed repaired gauge yet, so I can't tell you about the cost. I do know they have told me it is cheaper to repair then replace.
Mike E
Dynamic Motorsports

[PANAVIA]

Another option is the Autometer Cobra Replica gauge, but they also suffer the "Bulb" oil problem. (tube kinks = dead gauge. )

[cobras]

ok it does work but it only goes up to the 40 mark and no higher, what could be causing that?

[Blas]

With a cold engine; carefuly remove the bulb end on the intake manifold and put it into a cup of boiling water. Check the gauge...water boils at 100 degrees C. You should be close to that temperature on the gauge. DON"T LOOSE THE BRASS WASHER......

[cobras]

blas what is this brass washer you are talking about?

[patrickt]

Originally Posted by cobras

blas what is this brass washer you are talking about?

That washer is what seals the bulb to the manifold. If you were able to get your needle to move my using the "knuckle technique" then I would continue whacking the guage, that's where the problem is.

[madmaxx]

I think you may also have to loosen the turn signal cancelling cam screw.

[cobras]

Originally Posted by madmaxx

I think you may also have to loosen the turn signal cancelling cam screw.

does anyone know if this is true, i dont want to break anything in trying to do this

[MEvang]

You can move the turn signal switch around as shown, but beware of a few things. First the wires to the switch are zip-tied tight against the steering column under the dash. You will need to cut a few of these ties loose in order to move the switch.
Second, you will have to spin the turn signal cancel cam also or it will not cancel correctly.
Therefore you might start this by removing the steering wheel and hub assembly. Looking at the cancel cam position and turn it 180* along with the switch.
I do have detailed instruction on this Email me and I'll see that you get them.
Mike E
Dynamic Motorsports
mike@dynamicmotorsports.net

[patrickt]

FWIW, my turn-signals self-cancel about 20% of the time -- I'm generally surprised when they do. I kind of think of it as an extension of the Smiths gauges that require thumping in order to work properly.

[cobras]

Originally Posted by MEvang

You can move the turn signal switch around as shown, but beware of a few things. First the wires to the switch are zip-tied tight against the steering column under the dash. You will need to cut a few of these ties loose in order to move the switch.
Second, you will have to spin the turn signal cancel cam also or it will not cancel correctly.
Therefore you might start this by removing the steering wheel and hub assembly. Looking at the cancel cam position and turn it 180* along with the switch.
I do have detailed instruction on this Email me and I'll see that you get them.
Mike E
Dynamic Motorsports
mike@dynamicmotorsports.net

and thank you Mike, for taking the time to help me out and sending me that info, even tho the car was not sold through your dealership, you still helped me out, i can imagine how great the customer service is you offer to your customers.

thanks again Mike

[madmaxx]

On the temperature gauge issue I remeber reading on SCOF it is very important how you run the the "wire" between the sending unit and guage. I do not think it is a wire but I know it is wrapped in a spring type enclosue. You need to log onto scoff and read, it may not be your guage or sending unit. In fact I bet it is not.

[cobras]

Originally Posted by madmaxx

On the temperature gauge issue I remeber reading on SCOF it is very important how you run the the "wire" between the sending unit and guage. I do not think it is a wire but I know it is wrapped in a spring type enclosue. You need to log onto scoff and read, it may not be your guage or sending unit. In fact I bet it is not.

Hi madmaxx thanks for posting, i have signed up to scof but have to wait till they aprove me i guess, i also joined the other sitr...dont remember the name off the top of my head now, but also have to wait till they aprove me, so not sure how long that will be. any chance any of you can post a link to that.

i will try logging in and seeing if it lets me in

thanks for help though

[MEvang]

I think what madmaxx is trying to point out is, care must be taken when you run the capillary tube (wire). This is actually a tiny tube filled with ether. The expansion of the ether through the tube is what causes the gauge needle to move. Sharp bends, twisting or the accidental contact with an electrical source can cause the small copper tube to fracture and leak out the ether.
Mike E
Dynamic Motorsports

[madmaxx]

cobras

you have a pm