Help with a temp problem (1 Viewer)

Joined
Dec 27, 2018
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32
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Louisiana
I need some help. What test should i run to see if i have a bad thermostat or a blown head gasket? Ive had the needle get close to the red line but never touched. Went take a ride and the needle would get warm and warmer them go back to normal. It did this all the way back home (65 miles). I checked the oil its not milky and no white smoke coming from the tail pipe. I was low on coolant and when I put more in about a month ago it was good till today's ride. I was hoping that I had a crack in the overflow tank that I could fix. But it dont look like it. I had a appointment with my mechanic next week to adjust the TBS because it wasn't running right. Could this be connected to a blown end gasket?
 
Joined
Jul 17, 2018
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1,053
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KN4YJE LUGOFF, SC
I've never had the problem. When I put new coolant in, first I fully fill the radiator and coolant system through the radiator cap. I idle the rig, level, with the radiator cap off and add coolant as needed until it won't take anymore, then I burp the top radiator hose by hand, squeezing it, and add more coolant as needed until it won't take any more. And then I seal it up, top off the overflow tank and call it good.
 
Joined
Nov 18, 2019
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327
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Albuquerque NM
Also make sure the overflow bottle is filled for a few engine heat up/cool down cycles, it will purge the air and suck in more coolant over time as needed, if your radiator cap is working.
 

DSRTRDR

I can mangle anything ...
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Joined
Jan 4, 2005
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15,260
Location
Baton Rouge, LA and Fountain Hills, AZ
I need some help. What test should i run to see if i have a bad thermostat or a blown head gasket? Ive had the needle get close to the red line but never touched. Went take a ride and the needle would get warm and warmer them go back to normal. It did this all the way back home (65 miles). I checked the oil its not milky and no white smoke coming from the tail pipe. I was low on coolant and when I put more in about a month ago it was good till today's ride. I was hoping that I had a crack in the overflow tank that I could fix. But it dont look like it. I had a appointment with my mechanic next week to adjust the TBS because it wasn't running right. Could this be connected to a blown end gasket?

what year truck ?

if OBDII, I strongly suggest you invest in an Ultragauge to read the actual coolant temperature (and other parameters)

if OBDI, a Koso gauge will do the same, just requires more work to install

and, we are based in Baton Rouge :cheers:
 

mudgudgeon

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Dec 17, 2007
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4,633
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Sydney, Australia
The toyota temperature gauges has a reputation for being too slow to react when temperatures get high.
If it's getting up toward the red, don't take it lightly.
@DSRTRDR Suggestion of using an engine monitor is a good idea

You say it's not running right? What is the symptom?

If it's running rough, and temperatures are creeping up to the red, odds are high you've got a bad head gasket IMO

May not be HG, so it's worth checking simple things too.
Radiator caps wear out, and you can lose coolant if the cap is not functioning properly
 
Joined
Aug 22, 2010
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2,556
Location
Jersey, 07740
for the cost of the thermostat you might as well just replace it, if your going to go over the cooling system replace it as a matainence item. to better monitor the coolant temp you can add an aftermarket temp gauge
 

leonard_nemoy

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Jan 19, 2005
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South west utah
Year? Mileage?

New thermostat, radiator cap, and coolant. Than take it for a test drive. Might as well do new hoses and a fan clutch while your at it. Maybe even a new water pump and radiator if they are original and lots of crap comes out when you drain the radiator.
 

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