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.

[cobras]

ok found the copper washer and now i know why you say dont loose it, as for the hot water method, tried it 2 time hoping it would shock it or loosen it up even tapped on the back of the guage with the handle of a screw driver but nope nada zip, guage just goes up to the 50 mark, i was saying the 40 mark before but thats where the needle sits
so no luck there, well it does go up to 50 hahaha, looking at it it seems like an easy re and re of the guage but looks like i need to remove the steering wheel to get the guage out. am i wrong with saying that. also what other options as to guage wise do i have? how hard will it be to wire it up to work. looking under that dash... not to much room to put my big hands, never mind loosening stuff of and such

[Dwight]

you can use a heat gun or hair dryer to heat the bulb

Dwight

[Blas]

The gauge comes out without removing the dash. You can remove the steering wheel. Hardest part is not scraching it taking the center horn button off. Use some fishig line run around the crease in case silicone was used to mount it. A small hand can probably replace the gauge with just removing the tach to get access. You probably have lost part of the gas charge in the bulb and Bourdon Tube, so it reads low. It will eventually stop reading completely. You already have learned more about your new car then many others.......Isn't this fun?

[patrickt]

Originally Posted by cobras

how hard will it be to wire it up to work. looking under that dash... not to much room to put my big hands, never mind loosening stuff of and such

You're going to have to replace the gauge. I don't know about the SPF speedo trick, but if it's like the ERA then you're going to have to remove the screws holding the dash and pull the dash back towards you a couple of inches in order to get room to work. The wiring to a mechanical gauge is simple and straight-forward. Getting to the gauge is the trickiest part.

[ekrupa2]

Another option is the electric Kirkham gauges...if my Smiths ever fail this is what I would be replacing them with.
http://www.thomaskirkham.com/index.html

[patrickt]

For what it's worth, my Smiths stick and I have to rap them with a knuckle to make them start working. Passengers love it -- it just adds to the "step back in time" aura that the car has.

[cobras]

i wish all i had to do was knock on the guage to make it work, but for me i donthave that luck.
i can see that being kinda cool having to knock it oncein a while talk about old school.

Blas... hsving fun yet??? thats an understatement its like 2 deg over here and rainy and snow flurries at times, damm i was thinking of just tearing the whole car apart and clean it all with a tooth brush and put it all bsck together well u are right i am learning the pros and cons right quick... why just wet ur toe in the pool when you can jump in head first lol.
so ur saying i just have to remove the tach and i will be able to undo the bracket on the back of the temp guage? no need to remove the wheel to slide the guage out?

and another thing that turn siginal on the right side is a bit of a pain, will it fit on the left side and still work properly an have clearance to not hit the dash?



thanks everyone whos posted its ahuge help

[patrickt]

Originally Posted by cobras

so ur saying i just have to remove the tach and i will be able to undo the bracket on the back of the temp guage? no need to remove the wheel to slide the guage out?

If you decide to forego the speedo/tach trick and, instead, move the dash back you do not have to remove the steering wheel. Just loosen the dash screws and that will give you a couple of inches (on an ERA, that is; someone correct me if I am completely wrong on an SPF).

Originally Posted by cobras

... that turn siginal on the right side is a bit of a pain, will it fit on the left side and still work properly an have clearance to not hit the dash?

I have mine on the left side (a lot of us do). Again, you should be able to loosen the bracket that holds the signal and rotate it around the steering shaft without having to remove the steering wheel or bracket itself (you "click" the turn signal in the same direction regardless of whether the signal is on the left or right side of the steering column).

[cobras]

hey patrickt

could you give som more detail on the bracket you say to loosen to twist the turn signal arm to the left side. so i do not need to remove the steering wheel for this mod?