Overheats Then Drops To Operating Temperature - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Fixwhataintbroke · 01-25-2013, 11:02 PM

As the title says, my 92 k1500 w/ stock 350 overheats then drops back down to operating temperature. I've installed two aftermarket gauges and replaced the sending unit several times, always it goes to 260 turning on the check engine light, then i assume once the thermostat opens, the temperature plummets to 210, or, depending on the thermostat temperature i chose, as low as 140ish. I've replaced the thermostat several times also, but always stuck with Oreilly brand (garbage I'm starting to believe). Has anybody experienced this our have any insight what is causing it and/or what can be done took remedy it. I'm selling it to get another square and i just want it fixed so the next owner wont have this issue.

Oh yea and with no thermostat, it doesn't even get close to warm, which is proper...thankfully
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ChevyTech · 01-26-2013, 11:48 AM

I would put a Stant 195 degree thermostat in it. I believe the NAPA brand T-stats are made by Stant.

If the head gaskets are starting to leak it can push a little air into the cooling system. The air will go to the top. When you start it cold, if there is a air bubble at the thermostat rather then water, the thermostat will not open until the engine gets overheated.

If you want to try something, take any brand 195 degree thermostat and drill a small hole in it so air bubbles do not get trapped at the thermostat. This may take care of the problem you are experiencing, but you should test to see if the head gaskets are starting to leak.

Fixwhataintbroke · 01-27-2013, 05:18 PM

It's funny you mention that because it just so happens that there is a small trickle of coolant on the back of the driver's side head, didn't notice it till i saw a small wet spot under there. That and I just noticed the weep hole on the water pump leaks when running cold.

Fixwhataintbroke · 01-27-2013, 06:35 PM

Drilled a small hole in the failsafe 180 I've got in it, climbed to roughly 170-180 and dropped and held 140-150. I'll have the heads milled and checked, that way I know there's no warpage or any cracks (may as well right?). Then replace the water pump, and get a stant thermostat for grins

01-25-2013, 11:02 PM	#1
Fixwhataintbroke Enthusiast Join Date: Jun 2010 Location: Graham, Wa. Posts: 192	Overheats Then Drops To Operating Temperature As the title says, my 92 k1500 w/ stock 350 overheats then drops back down to operating temperature. I've installed two aftermarket gauges and replaced the sending unit several times, always it goes to 260 turning on the check engine light, then i assume once the thermostat opens, the temperature plummets to 210, or, depending on the thermostat temperature i chose, as low as 140ish. I've replaced the thermostat several times also, but always stuck with Oreilly brand (garbage I'm starting to believe). Has anybody experienced this our have any insight what is causing it and/or what can be done took remedy it. I'm selling it to get another square and i just want it fixed so the next owner wont have this issue. Oh yea and with no thermostat, it doesn't even get close to warm, which is proper...thankfully Posted via Mobile Device __________________ - Cole 1979 Chevy C30 w/ carb 454. 1992 Chevy K1500 w/ tbi 350. Sold 1997 Dodge Ram 1500 w/ Magnum 360 Sold "Good judgment comes from experience. Experience comes from poor judgment." - George Washington

01-26-2013, 11:48 AM	#2
ChevyTech Registered User Join Date: May 2004 Location: Minnesota Posts: 4,620	Re: Overheats Then Drops To Operating Temperature I would put a Stant 195 degree thermostat in it. I believe the NAPA brand T-stats are made by Stant. If the head gaskets are starting to leak it can push a little air into the cooling system. The air will go to the top. When you start it cold, if there is a air bubble at the thermostat rather then water, the thermostat will not open until the engine gets overheated. If you want to try something, take any brand 195 degree thermostat and drill a small hole in it so air bubbles do not get trapped at the thermostat. This may take care of the problem you are experiencing, but you should test to see if the head gaskets are starting to leak. __________________ For those of you that are wondering why you are not getting replies to your thread: Did you give the model, year, engine, fuel system type, and transmission information? If it is modified from what came stock from the factory, let us know that too.

01-27-2013, 05:18 PM	#3
Fixwhataintbroke Enthusiast Join Date: Jun 2010 Location: Graham, Wa. Posts: 192	Re: Overheats Then Drops To Operating Temperature It's funny you mention that because it just so happens that there is a small trickle of coolant on the back of the driver's side head, didn't notice it till i saw a small wet spot under there. That and I just noticed the weep hole on the water pump leaks when running cold. __________________ - Cole 1979 Chevy C30 w/ carb 454. 1992 Chevy K1500 w/ tbi 350. Sold 1997 Dodge Ram 1500 w/ Magnum 360 Sold "Good judgment comes from experience. Experience comes from poor judgment." - George Washington

01-27-2013, 06:35 PM	#4
Fixwhataintbroke Enthusiast Join Date: Jun 2010 Location: Graham, Wa. Posts: 192	Re: Overheats Then Drops To Operating Temperature Drilled a small hole in the failsafe 180 I've got in it, climbed to roughly 170-180 and dropped and held 140-150. I'll have the heads milled and checked, that way I know there's no warpage or any cracks (may as well right?). Then replace the water pump, and get a stant thermostat for grins __________________ - Cole 1979 Chevy C30 w/ carb 454. 1992 Chevy K1500 w/ tbi 350. Sold 1997 Dodge Ram 1500 w/ Magnum 360 Sold "Good judgment comes from experience. Experience comes from poor judgment." - George Washington



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