Car repair

[mayor]

My son has a 1967 ford fairlane 289. Having problems with temperature idiot light. It stays on. Changed the sending unit. Have a schematic. I'm pretty sure it is a wiring problem but until we can hunt down the problem, i need to add a temperature gauge. So, I've come to the smartest people on the internet - even smarter than the google. I've looked for a gauge and have found several, but I want a recommendation for the gurus here. I want a single gauge. thanks!

[G.A. Heath]

I would recommend a purely mechanical unit that uses a copper thermocouple that runs from the engine to the guage. If you have to drill a hole in the firewall be sure to use a rubber grommet to protect the thermocouple or wires (I would recommend simply punching a small hole in an existing rubber grommet instead).

Edit to Add: Nice Car, but it could be more than what you think. Check to see if the water pump is on it's way out first. To do this make sure the engine is off and try to wiggle the fan from side to side. If there is very much movement then you have a problem. Next with the engine cool open the radiator cap, turn on the heater, and start the engine. You should see some movement in the fluid at the top, even when the thermostat is closed (If need be rev the engine). If you have no movement in the water you have a bad water pump or blockage somewhere. With the radiator cap off toss it in the trash and put a replacement on (Cheap insurance and this fixes 1/3 of the engine overheating problems on older cars). On the front of the intake manifold there is a 90 degree elbow that your radiator hose and one smaller hose connect to. You can drain some fluid, remove that elbow, take the disk inside it out, clean the surfaces, put a thin layer of silicon on one surface, bolt the elbow back onto the intake and refill the coolant. If the problem goes away get a new thermostat (160 or 180 degree temperature rating for that car IIRC) and repeat the steps to put the unit back in.

Finally get a Haynes manual for that car, it should have a wiring diagram in it.

[warnmar10]

If you unplug the sending unit do the light go out?

[C-dub]

I would also like to know why the light is on before moving on to install an actual gauge. The gauge might still be useful, but one thing at a time.

[WTR]

Never been a fan of idiot lights. I cut my teeth on a 65 FF /289. My Dad showed me how to install a 3 gage cluster. Oil, Water Temp, Voltage. Nice Saturday project.

[mayor]

I had the water pump changed a few months ago. I had to change out the radiator and heater core due to leaks. while we were checking out the repairs, the light was on. I know it isn't hot because we flushed the cooling system before replacing everything. the water was running clear. has new radiator and heater core. replaced sending unit, still have light, pulled plug off of unit, still have light. i'm pretty certain it is electrical. we had to pull the most everything out of the dash to remove the heater/ac box. after reinstall, we have this light. I've got a schematic and there really isn't much to that circuit. replaced the little voltage regulator behind the dash. I've been incorrect before, but I'm pretty sure it isn't hot. that's why I want to install a gauge. The three gauge clusters are easier to get. may go that route.
this is my son's learn to mechanic car. he's getting a head full and a pocket empty.

[mrvmax]

If you were closer I’d lend a hand, I’ve got a tool used to track down shorts. I’m no electrician but I’ve tracked down a few wiring problems and for me it’s usually due to a short. You can pick up gauges at Jegs or Summit and they are easy to install. I always preferred having at least temp and oil pressure.

[warnmar10]

...


, pulled plug off of unit, still have light.


...

That wire is shorted to ground somewhere between where it attaches to the sending unit and the red lamp on the dash.
I'd start tracing the wire starting from the sending unit to the firewall.

[mayor]

...


, pulled plug off of unit, still have light.


...

That wire is shorted to ground somewhere between where it attaches to the sending unit and the red lamp on the dash.
I'd start tracing the wire starting from the sending unit to the firewall.

good idea. I'll disconnect it at the firewall and jump the wires going to the coil so it will run and see if we still have a light. at least that will let us know which direction to look.

if we don't find it tomorrow, he needs to get something so he knows the temp is OK until we can run it down. I hate electrical problems. we checked the ground strap from the block to the firewall. disconnected it, scrubbed it and the firewall connection down with a wire brush and reconnected. I've seen that cause weird problems. still no luck.

[G.A. Heath]

I am leaning towards it's probably damage to the wiring from age or rodents. A gauge, especially in a car this old, is almost a requirement if you plan to drive it much. Keep in mind that repairs over the years may have been less than ideal too, a damaged wire may have been repaired by cutting, stripping insulation, twisting together, and wrapping with cloth black tape. The minimum for the proper way to splice a wire is much more involved.

On a side note: when I was little my parents had a '66 Fairlane Convertible w/ an FE series engine (specifically 390 I think) that my dad planned to restore one day. They sold it to my uncle who passed away a few days ago, I don't know what ever happened to that car but that body style has always been one of my favorites.

[mayor]

the wires under the dash are less than ideal, but for 50 years old, the harness is still in fairly good shape. there have been some 'repairs' done. the harness under the hood going to the temperature sending unit is especially doctored. it could be the ignition switch, maybe?

it is a nice, cool looking car. We got a sedan because we couldn't find an affordable coupe. I put way more money in it than I wanted, but it needed to be safe and reliable. it runs really well. he's finding out all about gas milage. it got him through 2 years of high school fine. now, things, like me, are beginning to show some age.

[WTR]

I went through about 5 water pumps and a compressor clutch on mine. However, I was using Checker Auto Parts in the day, that may have been the WP issue. Other than that, you can sure wear out the back right tire quickly.

[2farnorth]

Check the bulb socket. (if you can get to it) Sounds like its shorted to ground. As I remember it, if it is a singled wire sender then the wire on the sending unit completes the ground path in an overheat condition. If you have a light with the wire disconnected from the sender then there is an alternate ground path.

[mayor]

Check the bulb socket. (if you can get to it) Sounds like its shorted to ground. As I remember it, if it is a singled wire sender then the wire on the sending unit completes the ground path in an overheat condition. If you have a light with the wire disconnected from the sender then there is an alternate ground path.

I'll remove the socket from the instrument cluster. if it is grounded there, it should extinguish.

lots of good ideas. thanks. I knew these are the smartest people on the interwebs.

[RPBrown]

Autozone has several single temp gauges