Heat Temp Sensor? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Richard Dobson · 10-31-2007, 09:17 PM

I got my 396 engine started a let it run for approx 15 minutes with no movement on the temperature gage. I have put in a new 180 deg thermostat, new alum water pump, new hoses. I have a 4 core rad. Have I let the engine run long enough? The hoses were hot, the rad was hot, so I was concerned when the temp gage showed no movement at all and shut the eng off. I ran a wire from the temp sending unit to a bolt on the intake and had the wife watch the temp gage and it pegged out to the hot position. Does this mean the sending unit is bad? Thanks for all replies.

Longhorn Man · 10-31-2007, 09:49 PM

Sounds like a faulty sending unit to me.
If the rad and hose are warm, or hot, then the engine is certinaly warmed up.
By grounding the sending unit, you tested the wire and guage, and they responded correctly by pegging out.

**VetteVet** · 10-31-2007, 10:20 PM

By shorting the temp sender to the block you bypassed the sender to ground resistance.
This shows that 1. You have a bad sender or 2. the sender is not connecting to the ground (cylinder head ). Try running a jumper from the sender housing to ground and if you get a reading it means the sender is not grounded good. Did you use any sealant on the sender threads?

Richard Dobson · 11-01-2007, 08:24 PM

Yeah, I used teflon tape. I bought a new sending unit put it on a it works fine. The only thing is I need the little thingy that goes on top of the sending unit for the electric lead to attach to. Regards

10-31-2007, 09:17 PM	#1
Richard Dobson Registered User Join Date: Apr 2003 Location: Easley, South Carolina Posts: 491	Heat Temp Sensor? I got my 396 engine started a let it run for approx 15 minutes with no movement on the temperature gage. I have put in a new 180 deg thermostat, new alum water pump, new hoses. I have a 4 core rad. Have I let the engine run long enough? The hoses were hot, the rad was hot, so I was concerned when the temp gage showed no movement at all and shut the eng off. I ran a wire from the temp sending unit to a bolt on the intake and had the wife watch the temp gage and it pegged out to the hot position. Does this mean the sending unit is bad? Thanks for all replies. __________________ Richard Dobson

10-31-2007, 09:49 PM	#2
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	Re: Heat Temp Sensor? Sounds like a faulty sending unit to me. If the rad and hose are warm, or hot, then the engine is certinaly warmed up. By grounding the sending unit, you tested the wire and guage, and they responded correctly by pegging out.

10-31-2007, 10:20 PM	#3
VetteVet Msgt USAF Ret Join Date: Jan 2005 Location: Kalamazoo, Michigan Posts: 8,709	Re: Heat Temp Sensor? By shorting the temp sender to the block you bypassed the sender to ground resistance. This shows that 1. You have a bad sender or 2. the sender is not connecting to the ground (cylinder head ). Try running a jumper from the sender housing to ground and if you get a reading it means the sender is not grounded good. Did you use any sealant on the sender threads? __________________ VetteVet metallic green 67 stepside 74 corvette convertible 1965 Harley sportster 1995 Harley wide glide Growing old is hell, but it beats the alternative. Last edited by VetteVet; 10-31-2007 at 10:22 PM.

11-01-2007, 08:24 PM	#4
Richard Dobson Registered User Join Date: Apr 2003 Location: Easley, South Carolina Posts: 491	Re: Heat Temp Sensor? Yeah, I used teflon tape. I bought a new sending unit put it on a it works fine. The only thing is I need the little thingy that goes on top of the sending unit for the electric lead to attach to. Regards __________________ Richard Dobson



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