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#1 |
Registered User
Join Date: Jan 2015
Location: Ventura, CA
Posts: 818
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Bad temp gauge or gonna blow up?
My truck (from what the gauge says) has been running warmer lately. Plus, the gauge is moving in temp a lot. You know right before your thermostat opens, you see the gauge climb a little then it drops when the thermostat opens? Well mine seems to climb a little higher than normal, then it drops a lot, then it climbs again, drops a lot. I have a 3 core alum radiator and she normally runs really cool. Yes, I have fluid in it. no leaks that I know of. So Bad, gauge, thermostat or gonna blow up?
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..................... ____ .........________//__{\_____ ,,,,,,,/__(O)___//___/__(O)_/ 1970 C20 -_--_--_- ______ _--_--_- /___|__\____ -_--_-_ |_(0)|__|_(0)] 1972 K5 |
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#2 |
Registered User
Join Date: Nov 2014
Location: Bigfork, Montana
Posts: 1,137
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Re: Bad temp gauge or gonna blow up?
My guess is thermostat. when a gauge is bad it usually goes high or low, it doesn't fluctuate. The tstat is sticking & then opening at a higher temp. Even if this is NOT the problem it's cheap to try & eliminates one variable.
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#3 |
Registered User
Join Date: Oct 2016
Location: Dallas Texas
Posts: 3,090
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Re: Bad temp gauge or gonna blow up?
It's gonna blow up.
-klb LOL
__________________
67 C10 fleet fuel injected '70 402, 700r4, 3.73 posi 07 335 sport turbo 6sp 94 Trans Am GT LT1 6sp posi -- sold after 22yrs 99 540 sport V8 6sp -- sold 73 240z L24 4sp -- given to friend 68 C10 step 350/350 3.73 open -- sold |
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#4 |
Registered User
Join Date: Jan 2015
Location: Ventura, CA
Posts: 818
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Re: Bad temp gauge or gonna blow up?
WTF weq92f No, I will try the thermostat and let you guys know the outcome. Start with the cheap parts first.
__________________
..................... ____ .........________//__{\_____ ,,,,,,,/__(O)___//___/__(O)_/ 1970 C20 -_--_--_- ______ _--_--_- /___|__\____ -_--_-_ |_(0)|__|_(0)] 1972 K5 |
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#5 |
Registered User
Join Date: Aug 2016
Location: Lake Forest, CA
Posts: 2,177
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Re: Bad temp gauge or gonna blow up?
How about using a temp gun to check temperatures of the engine and compare to the gauge. Where is your temp sender? If its reading the t stat that much, my assumption is its in the intake manifold by the t stat housing. I would move it to the head as the factory intended the temp to be monitored.
The middle of the gauge could be 200 degrees and is OK. As long as it's not pinging or having detonation issues, the higher the combustion tempos, the more fuel is burnt efficiently. Your fan does look like it sits inside the shroud a bit too much. My 70 with a stock 350 barely comes off the first tick after the cold mark. I have never thought about it running cold, I just figured its a poor sender or old gauge in my case. I have a 180 with a 4-row radiator, shroud and fan clutch. Heater gets plenty hot.
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"Work hard, use your vacation days." 1970 C15 GMC Long Bed 1986 C20 Scottsdale 1983 K2500 Sierra Classic Suburban 6.2 Instagram: C10sofOC |
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#6 |
Registered User
Join Date: Aug 2006
Location: Redmond, WA
Posts: 6,332
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Re: Bad temp gauge or gonna blow up?
I'll pile on about the fan - if you have spacer, toss it I think. You want it half in, half out of the shroud usually.
The middle of the gauge is about 200 when I checked once. That's about where a 195F thermostat should open.
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1970 GMC Sierra Grande Custom Camper - Built, not Bought 1969 Pontiac 2+2 427/390 4-speed Coupe 1969 Pontiac 2+2 427/390 4-speed Convertible |
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#7 |
Registered User
Join Date: Jan 2015
Location: Ventura, CA
Posts: 818
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Re: Bad temp gauge or gonna blow up?
I have had the fan in this place since we built the truck. For the last year it has been running ice cold. So I believe it is another problem. But I'm open to anything.
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..................... ____ .........________//__{\_____ ,,,,,,,/__(O)___//___/__(O)_/ 1970 C20 -_--_--_- ______ _--_--_- /___|__\____ -_--_-_ |_(0)|__|_(0)] 1972 K5 |
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#8 |
Registered User
Join Date: Jan 2015
Location: Ventura, CA
Posts: 818
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Re: Bad temp gauge or gonna blow up?
Update. while changing the thermostat, one of my friends stopped by. Whom, i believe is smarter than me. He said grab the fan and see if it spins. Engine is cold. Fan spins both directions with no resistance. No it is not electric. does this mean the fan clutch is bad?
Note... put in new thermostat, it did not fix anything.
__________________
..................... ____ .........________//__{\_____ ,,,,,,,/__(O)___//___/__(O)_/ 1970 C20 -_--_--_- ______ _--_--_- /___|__\____ -_--_-_ |_(0)|__|_(0)] 1972 K5 |
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#9 | |
The Older Generation
![]() ![]() ![]() Join Date: Aug 2006
Location: Montezuma, Iowa
Posts: 25,487
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Re: Bad temp gauge or gonna blow up?
Quote:
Fan should turn but it should have quite a bit of resistance. I would say that your fan clutch is possibly bad. You didn't say where your sender is located. If the picture you posted is all the hotter it gets by the gauge, the radiator has coolant in it and it's not boiling over, I wouldn't worry about it.... LockDoc
__________________
Leon Locksmith, Specializing In Antique Trucks, Automobiles, & Motorcycles (My Dually Pickup Project Thread) http://67-72chevytrucks.com/vboard/s...d.php?t=829820 - |
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#10 | |
Registered User
Join Date: Jan 2015
Location: Ventura, CA
Posts: 818
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Re: Bad temp gauge or gonna blow up?
Quote:
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..................... ____ .........________//__{\_____ ,,,,,,,/__(O)___//___/__(O)_/ 1970 C20 -_--_--_- ______ _--_--_- /___|__\____ -_--_-_ |_(0)|__|_(0)] 1972 K5 |
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#11 |
The Older Generation
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Location: Montezuma, Iowa
Posts: 25,487
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Re: Bad temp gauge or gonna blow up?
It will work there but that location is not ideal, as there will be more fluctuation in the gauge as one would expect, because of the thermostat opening and closing. I realize the problem you are facing with the later style heads too....
LockDoc
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Leon Locksmith, Specializing In Antique Trucks, Automobiles, & Motorcycles (My Dually Pickup Project Thread) http://67-72chevytrucks.com/vboard/s...d.php?t=829820 - |
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#12 |
Registered User
Join Date: Jan 2015
Location: Ventura, CA
Posts: 818
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Re: Bad temp gauge or gonna blow up?
So should I get a different shroud or fan?
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..................... ____ .........________//__{\_____ ,,,,,,,/__(O)___//___/__(O)_/ 1970 C20 -_--_--_- ______ _--_--_- /___|__\____ -_--_-_ |_(0)|__|_(0)] 1972 K5 |
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#13 | |
Registered User
Join Date: Aug 2016
Location: Lake Forest, CA
Posts: 2,177
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Re: Bad temp gauge or gonna blow up?
Quote:
Get a temperature gun and confirm the engine is actually getting hot. What degree t stat did you pull out and put back in?
__________________
"Work hard, use your vacation days." 1970 C15 GMC Long Bed 1986 C20 Scottsdale 1983 K2500 Sierra Classic Suburban 6.2 Instagram: C10sofOC |
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#14 |
Registered User
Join Date: Jan 2015
Location: Ventura, CA
Posts: 818
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Re: Bad temp gauge or gonna blow up?
195 old and new. my temp gun is at home. fan free spins when engine is hot or cold.
__________________
..................... ____ .........________//__{\_____ ,,,,,,,/__(O)___//___/__(O)_/ 1970 C20 -_--_--_- ______ _--_--_- /___|__\____ -_--_-_ |_(0)|__|_(0)] 1972 K5 |
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#15 |
Registered User
Join Date: Jan 2015
Location: Ventura, CA
Posts: 818
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Re: Bad temp gauge or gonna blow up?
Just remove these to get the fan clutch out? Not the 4 bolts on the water pump?
__________________
..................... ____ .........________//__{\_____ ,,,,,,,/__(O)___//___/__(O)_/ 1970 C20 -_--_--_- ______ _--_--_- /___|__\____ -_--_-_ |_(0)|__|_(0)] 1972 K5 |
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#16 |
Registered User
Join Date: Jan 2015
Location: Ventura, CA
Posts: 818
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Re: Bad temp gauge or gonna blow up?
fan spins free when hot or cold
__________________
..................... ____ .........________//__{\_____ ,,,,,,,/__(O)___//___/__(O)_/ 1970 C20 -_--_--_- ______ _--_--_- /___|__\____ -_--_-_ |_(0)|__|_(0)] 1972 K5 |
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#17 |
Registered User
Join Date: Aug 2016
Location: Lake Forest, CA
Posts: 2,177
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Re: Bad temp gauge or gonna blow up?
You gotta take the bolts off the water pump pulley to get the fan and fan clutch off, then remove those bolts.
Ok another question: Does it only get hot when sitting and running or when going down the freeway?
__________________
"Work hard, use your vacation days." 1970 C15 GMC Long Bed 1986 C20 Scottsdale 1983 K2500 Sierra Classic Suburban 6.2 Instagram: C10sofOC |
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#18 |
Registered User
Join Date: Oct 2016
Location: Dallas Texas
Posts: 3,090
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Re: Bad temp gauge or gonna blow up?
The bad clutch may explain the hotter than normal gauge reading as well as the higher cycling range during thermostat cycles that you observed.
As for the too cool, that could be too cool a thermostat or something else but it sounds like you need a new clutch ( and maybe change the location in the shroud ) and you'll be back to 'normal' -klb
__________________
67 C10 fleet fuel injected '70 402, 700r4, 3.73 posi 07 335 sport turbo 6sp 94 Trans Am GT LT1 6sp posi -- sold after 22yrs 99 540 sport V8 6sp -- sold 73 240z L24 4sp -- given to friend 68 C10 step 350/350 3.73 open -- sold |
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#19 |
Registered User
Join Date: Aug 2016
Location: Lake Forest, CA
Posts: 2,177
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Re: Bad temp gauge or gonna blow up?
Does it only get hot when sitting and running or when going down the freeway?
__________________
"Work hard, use your vacation days." 1970 C15 GMC Long Bed 1986 C20 Scottsdale 1983 K2500 Sierra Classic Suburban 6.2 Instagram: C10sofOC |
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#20 |
Registered User
Join Date: Jan 2015
Location: Ventura, CA
Posts: 818
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Re: Bad temp gauge or gonna blow up?
**Update**
put in new fan clutch. Drove it around for about 20 minutes then let is idle for 15 and this is where the temp stayed. thanks for all your help guys.
__________________
..................... ____ .........________//__{\_____ ,,,,,,,/__(O)___//___/__(O)_/ 1970 C20 -_--_--_- ______ _--_--_- /___|__\____ -_--_-_ |_(0)|__|_(0)] 1972 K5 |
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#21 | |
The Older Generation
![]() ![]() ![]() Join Date: Aug 2006
Location: Montezuma, Iowa
Posts: 25,487
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Re: Bad temp gauge or gonna blow up?
Quote:
Good deal! Glad you got it sorted out.... And thanks for coming back and posting the fix, too many people don't do that. LockDoc
__________________
Leon Locksmith, Specializing In Antique Trucks, Automobiles, & Motorcycles (My Dually Pickup Project Thread) http://67-72chevytrucks.com/vboard/s...d.php?t=829820 - |
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#22 |
Registered User
Join Date: Jan 2009
Location: San Antonio, Texas
Posts: 1,374
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Re: Bad temp gauge or gonna blow up?
Leon beat me to it, but I was going to say the same thing. Thanks for the closure -- so many threads never get updated with the final results.
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1972 C10 LWB, 350/350 Deconstruction began 5/2009, mostly completed restoration, 5/2017 |
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#23 |
Registered User
Join Date: Jan 2015
Location: Ventura, CA
Posts: 818
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Re: Bad temp gauge or gonna blow up?
tomorrow we figure out why my brake lights dont work.
__________________
..................... ____ .........________//__{\_____ ,,,,,,,/__(O)___//___/__(O)_/ 1970 C20 -_--_--_- ______ _--_--_- /___|__\____ -_--_-_ |_(0)|__|_(0)] 1972 K5 |
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#24 |
Registered User
Join Date: Oct 2016
Location: Dallas Texas
Posts: 3,090
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Re: Bad temp gauge or gonna blow up?
Nice! ++on the closure thing.
-klb
__________________
67 C10 fleet fuel injected '70 402, 700r4, 3.73 posi 07 335 sport turbo 6sp 94 Trans Am GT LT1 6sp posi -- sold after 22yrs 99 540 sport V8 6sp -- sold 73 240z L24 4sp -- given to friend 68 C10 step 350/350 3.73 open -- sold |
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