Engine Temp gauge fluctuations

[LCAM-01XA]

Most prefer electric gauges for the convenience of being able to install them anywhere they feel like. With mechanical gauges, if you have a concern about hot coolant spilling all over your cab should the line rub, that's not how they work - worst that will happen is the gas inside the line will vent and the gauge will drop to zero, as coolant never really leaves the engine. Mechanical oil pressure gauges on the other hand, oh yeah, them things can and will pump hot dirty oil all over the place if they let go - there are "gauge isolators" made for that very reason, but since it's usually their feed line that blows just using a simple steel-braided high-pressure line more or less takes care of that issue.

Bottom line, it's your decision, either type works. But e-gauges can be had in number of styles, including ones to match your factory Ford gauges on the dash. If, that is, you care for that.

 

[HS108]

Get an Electric one, If your spending the money on a Autometer gauge it should be high quailty, so I wouldnt worry about it.

 

[texcl]

Ordered and electric one will be here friday. Hope it is just the gauge, would a failing water pump make the gauge fluctuate? I would think that if the gauge was operating normally it wouldn't flutter as it take a little time for it to transfer the heat ect... i will disconnect the temp alarm unit when I get home tomorrow and see if it stops the flutter.

 

[chris142]

Another option is in the heater hose that comes off the head.make an adaptor and put your sender there.i did this in my jeep and its within 2* of what the ecm says. Dont put it after the heater as it will be too cool by then

 

[LCAM-01XA]

The rear of the intake has a port that can be used as well. Beware this one lags a bit, under high load the front of the engine will heat up faster than the rear does.

Or the same port used for the heater core coolant supply on the passenger-side head is also available in the driver-side head, pull the plug and drop your sender in. 1/2" NPT is what it is IIRC.

 

[texcl]

thanks for the info!

 

[texcl]

Alright I grounded the temp light connector and the temp light came on but didn't bury the temp needle, is that normal on 93's, thought it should make the needle bury itself in the hot zone. it's warming up now till the needle starts to bounce then will pull the temp light connector to see if it stops bouncing. Thinking the temp light is pretty usless and possibly replacing it with the new temp sensor/gauge then moving the temp light to the back hole and replacing the sender with a lower temp unit for good measure.

 

[madpogue]

^^^^ Yes, the temp light switch has no connection to the gauge. Likewise, the temp gauge sensor has no connection to the light. Completely independent circuits.

 

[texcl]

does anyone know the size of the temp light sender threads? It looks bigger than 1/2" for sure.

 

[LCAM-01XA]

1/2" NPT is significantly larger than 1/2" straight bolt and nut thread. Could be 3/4" NPT too... I'll have to get back to ya on that one, gotta measure ours and do some dimensions conversion.

 

[texcl]

I know it took a 15/16" socket to loosen it I tried to measure it in block and it is around 7/8" I think. Hopefully it is a 1/2" NPT so I don't have to wait on more parts. I think I'll just get a heater hose adapter if the adapters provided don't work. Need to have it done and tested this weekend so I can change the thermostat if need be. Could use the back plug but it is right next to the exaust manifold and I'm sure that will affect the temp readings and surely harden or melt the electrical connector over time.

More questions for you guys, what 12v supply do you guys recomend I plug into and how about the light's supply? Think the ground should be pretty easy.

 

[FORDF250HDXLT]

http://www.oilburners.net/forums/showthread.php?68054-Size-of-these-holes-Water-Temp-Stuff

 

[texcl]

Alright, it was a 1/2" NPT fitting. I set her all up and made one mistake. I used the 12v supply and ground off the cigarette lighter (which wasn't working anyway), I assumed that it turned off with the ignition but it runs all the time. Should I worry about this draining my battery? I would assume it would be a very minor drain especially once cool. By the way my engine ran between 195 and 205 degrees but mostly right around the 200-205 mark, the autometer unit certainly didn't fluctuate like the OEM one does. When my OEM gauge is at the R the autometer is reading around 200 degrees.

 

[LCAM-01XA]

Don't you have a separate 12V outlet that is not the cigarette lighter? IIRC the OBS trucks have two of them things, the cig lighter that is constant 12V and the other is key-only?

If not, then you really have no convenient key-on power source. You can always use a Add-A-Circuit tap off one of the fuses under the dash, find one that's ignition-only and used fairly rarely and run off that, throw a 3-amp fuse in the tap block and you'll be golden.

You can connect to the dash lighting via the harness for the bulb above the ash tray. As in, pull bulb out, hack connector off, extend harness to your gauge. This will also provide a convenient ground, you can always use a 2nd ground path when it comes to gauges - you can run it for the bulb only, or you can share it with the ground for the gauge's guts, depending on how your particular gauge is set up.

 

[whiteboyslo]

Alright, it was a 1/2" NPT fitting. I set her all up and made one mistake. I used the 12v supply and ground off the cigarette lighter (which wasn't working anyway), I assumed that it turned off with the ignition but it runs all the time. Should I worry about this draining my battery? I would assume it would be a very minor drain especially once cool. By the way my engine ran between 195 and 205 degrees but mostly right around the 200-205 mark, the autometer unit certainly didn't fluctuate like the OEM one does. When my OEM gauge is at the R the autometer is reading around 200 degrees.

First off, congrats on the install.

I have the sensor for my Autometer gauge (electric w/ digital readout) in the same port as yours. My truck runs a bit cooler than yours, but not by much. On flat surfaces and at low/city speeds I run about 195°±5°F, and on the freeway and/or up longer grades it creeps up maybe 5 degrees or so. That's unloaded with the AC off. If yours is consistently running in the mid-200s even around town, you might want to think about a new thermostat. Mine used to run at 205°±5°F around town, but a new Motorcraft thermostat dropped that down. I even boiled the new thermostat and the old one to compare. The new one definitely opened a lot sooner and a lot wider than the old one.

As for your wiring issues, I'm assuming your gauge is digital like mine. Sounds like it, at least. Yes, technically the way you wired it will cause the gauge to be a draw on the battery all the time. Shouldn't be much since it's just LED, but also looks a but odd to have the gauge on all the time. I wired mine using fuse taps. All I had to do was find a circuit that was hot with the ignition, and another that was hot with the lights. I forget exactly which ones I tapped into, but a little studying of the fuse diagram and some common sense will get you through. I used fuse taps like these: http://shop.advanceautoparts.com/p/bussmann-atm-fuse-tap-10-amps-bp-hhh-rp/5080114-P. I like them because they give you a slot for a fuse for your new 'circuit' and even have a butt connector crimped on your new hot wire ready to go.

And as far as comparing your new readings to your stock gauge, you'll quickly start to realize how meaningless the stock one is. Granted, my truck is the generation before yours, but my temp gauge doesn't even come up to 'N' until I'm in the 210s.

Mike