Temperature norms for I6

[hevymetl]

Pretty sure I have a 250ci I6. The po had installed an electric fan controlled by a tstat sending unit that doesnt seem to be working. When I ground out the lead the fan goes on but left on the sending unit, it does not. If left to idle, the stock guage will eventually climb to at least 3/4s of the way to "H". I guess Im trying to figure out a few things at once. What are the corresponding temps vs. position of the needle on the guage? How do I know if that sending unit is or isnt working properly? Should I just pop off the tstat housing to check what tstat is in there for ****s n giggles? There is no shroud on the back of the radiator as well.
Thanks in advance, John.

[Tazimafied]

Your temp gauge should never go past half way. That is usually around 200 degrees but I'm not 100% sure on these.

Your sending unit is a thermal switch. They do fail form time to time which is what I am leaning towards in your situation. Or the PO just threw in whatever switch he could find. You can test the switch on your stove top with a pan of water, a thermometer and a ohm meter.

First thing I would do is look at the thermostat. Once you know the temp of the thermostat then I would order a new switch that turns on the fan 5 to 10 degrees hotter than the stat and should shut off 5 to 10 degrees cooler. This takes out the guess work and troubleshooting.

[TJ's Chevy]

Should have a 180 t-stat in there. The middle of the stock gauge is the Norm. These engines ran fairly cool...hitting 200 is normal in 100+ degree weather, but you really don't want to go much higher...I'd invest in a new sending unit that is a 180 and a 180 t-stat as well.

[Isaiah92260]

Originally Posted by TJ's Chevy

Should have a 180 t-stat in there. The middle of the stock gauge is the Norm. These engines ran fairly cool...hitting 200 is normal in 100+ degree weather, but you really don't want to go much higher...I'd invest in a new sending unit that is a 180 and a 180 t-stat as well.

Don't want to hi jack but I'm sure this may help a little to for @heavymetl

My truck goes back and forth around 195-210 F. It's been around 101 lately the past few weeks here in Palm Springs. Is that normal, from my understanding also, the OEM standard was 195 F. thermostat... So once it gets hotter during summer, is it wise to drop down the Thermostat to the 180?

[mechanicbob]

Make sure sending unit is grounded for single wire unit. Thread sealers can isolate sensor from grounding.

[hevymetl]

There don't seem to be any markings on the sender that I can see. Its just tapped into the top of the tstat housing. My overflow bottle is def not stock and isn't hooked up properly either. Any specific spot I should look for reference pics or parts to set it up correctly? Is that a pretty standard tstat that's in there or is it a special order item?

[TJ's Chevy]

Originally Posted by Isaiah92260

Don't want to hi jack but I'm sure this may help a little to for @heavymetl

My truck goes back and forth around 195-210 F. It's been around 101 lately the past few weeks here in Palm Springs. Is that normal, from my understanding also, the OEM standard was 195 F. thermostat... So once it gets hotter during summer, is it wise to drop down the Thermostat to the 180?

Well maybe I was wrong then. haha Even in 105 degree weather my 292 never went above the middle. And when driving it was usually just under. I guess 210 isn't to bad, the 496 in my 77 would hit 220 on a 100 degree day. lol

[hevymetl]

Originally Posted by mechanicbob

Make sure sending unit is grounded for single wire unit. Thread sealers can isolate sensor from grounding.

You read my mind MB. There is Teflon tape on it that I noticed. I was going to check that first. Ran out of time tonite. Thanks for confirming my thoughts.

[hevymetl]

Finally got around to changing tstat. Ends up there wasn't even one in there. I put in a 180°, now I just need to do a test drive or 2. Sitting in driveway at a high idle and at regular idle as well, temp gauge climbs to slightly above halfway then comes back down slightly below half when tstat opens.
Another bug I need to work out is the overflow. Its mounted on the pas side fender well. The hose from the radiator is hooked up to an inlet just below the cap on the bottle. When it heats up fluid goes into the bottle but then pours out a second port down low on bottle. Can I just move hose to the lower inlet to solve this? Could it be that simple?

[chevy_mike]

Yes, you want the overflow hose on the lower port so it can vent coolant into the tank and then suck it back in when it cools down.

[hevymetl]

Thank you Chevymike.