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#1 |
Got big-block?
![]() Join Date: Jul 2000
Location: Austin, Texas
Posts: 2,453
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overheating prob with new engine
I'm beginning to suspect a faulty gauge, but here's what's happenning:
Installed a new, dyno-tested 454 in my '77 Silverado. New radiator, waterpump, thermostat, hoses, temp sending unit, etc, etc. Filled with coolant. Fired up engine. While adjusting carb, setting idle, and checking for leaks, noticed temp gauge creeping toward HOT. Turned on heater to see if functioning or trapped air bubble. Heater works well, slowed temp gauge rise, but still got in the red HOT, so shut her down. Upper, lower radiator hoses hot to touch. No leaks. Let engine cool down. Drained coolant enough to remove thermostat housing. Removed thermostat, drilled small hole in thermostat to relieve any "air pocket" issues. Refilled radiator. Fired up engine. Took a test drive down the street and back. Pulled back in driveway, watched temp gauge go back up to red HOT. I'm going to try to verify gauge working properly. Any other thoughts? Thanks, SC
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'68 CST SWB factory 396/T400 buddy buckets, a/c, ps, pb '72 Corvette convertible 454/4spd/ac, ps, pb '73 GMC Sierra Grande short wide 454/T400 ps, pb, ac '77 K5 Blazer black on red, 350/T350/NP205 ps, pb, ac all original '78 GMC Sierra Classic short wide 454/T400 ps, pb, ac '72 GMC Sprint SP454. 1 of 38 built. '73 GMC Sprint SP454. 1 of 71 built. '75 GMC Sprint SP454. 1 of 25 built. SOLD! '72 GMC K25 4x4 468/4L80e/NP205 build thread http://67-72chevytrucks.com/vboard/s...23#post4324423 SOLD!'55 Chevy gasser 496/4spd build thread http://67-72chevytrucks.com/vboard/s...96#post4324396 |
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#2 |
my gas saver
Join Date: Sep 2003
Location: Clarksville, TN
Posts: 2,046
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how hot is your gauge, or what temp? my big block is always hot and i`ve heard it`s just the norm. it sets at like 230 sometimes and my last small block ran at a constant 180, so i kind of freaked at first.
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85' SWB, 4.3/TH350, getting ready for paint 84`SWB, 462ci./TH400, cowl hood, 15" billet spec., flows, blazer buckets/console, flat black 71`SWB, project ebay feedback |
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#3 |
Senior Member
![]() Join Date: Dec 2003
Location: Pampa, Texas
Posts: 1,553
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i got a 180 therm in my big block and my motor usually sits at 200 or 210 even with the 180....what degree therm do you have in there??
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https://www.ebay.com/itm/29620574751...mis&media=COPY |
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#4 |
CCRider
Join Date: Feb 2000
Location: Olive Branch,MS,USA
Posts: 2,232
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Get a cooking thermometer from a grocery store and remove the rad cap and put it in the coolant
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72 GMC Sierra SWB almost finished---- 84 Softail Olive Branch MS |
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#5 |
Registered User
Join Date: Jun 2002
Location: Knoxville Tenn.
Posts: 3,058
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What year 454? Might have a reverse flow pump.
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56 Chevy Bel-Air 2dr. HT (purchased new) 71 Chevy Cheyenne SWB PU (502HO) 65 GMC short bed step--work in progress and my gofer |
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#6 |
Got big-block?
![]() Join Date: Jul 2000
Location: Austin, Texas
Posts: 2,453
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I've got a 180 therm in it.
It's a '73 454 and heads; nothing special; .030 over, 9:1 flat tops, little bit of a cam. I'm going to put an aftermarket water temp gauge in it tonight, and see just how hot it gets. I'll post the result. Thanks, SC
__________________
'68 CST SWB factory 396/T400 buddy buckets, a/c, ps, pb '72 Corvette convertible 454/4spd/ac, ps, pb '73 GMC Sierra Grande short wide 454/T400 ps, pb, ac '77 K5 Blazer black on red, 350/T350/NP205 ps, pb, ac all original '78 GMC Sierra Classic short wide 454/T400 ps, pb, ac '72 GMC Sprint SP454. 1 of 38 built. '73 GMC Sprint SP454. 1 of 71 built. '75 GMC Sprint SP454. 1 of 25 built. SOLD! '72 GMC K25 4x4 468/4L80e/NP205 build thread http://67-72chevytrucks.com/vboard/s...23#post4324423 SOLD!'55 Chevy gasser 496/4spd build thread http://67-72chevytrucks.com/vboard/s...96#post4324396 |
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#7 |
Registered User
Join Date: Nov 2001
Location: Concord, NC
Posts: 2,488
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superchevy, how about the fan, clutch, and shroud? Is the setup all stock?
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#8 |
Got big-block?
![]() Join Date: Jul 2000
Location: Austin, Texas
Posts: 2,453
|
Well, it must have been a faulty sending unit or gauge, as I installed a Sun temp gauge and sending unit just now, and it never got over 190. I was worried a bit, because I need to run some line pressure tests on the 700R4 to get it dialed in right, and you have to be able to idle for awhile to do that.
One step closer to getting her on the road. Thanks for the help, SC
__________________
'68 CST SWB factory 396/T400 buddy buckets, a/c, ps, pb '72 Corvette convertible 454/4spd/ac, ps, pb '73 GMC Sierra Grande short wide 454/T400 ps, pb, ac '77 K5 Blazer black on red, 350/T350/NP205 ps, pb, ac all original '78 GMC Sierra Classic short wide 454/T400 ps, pb, ac '72 GMC Sprint SP454. 1 of 38 built. '73 GMC Sprint SP454. 1 of 71 built. '75 GMC Sprint SP454. 1 of 25 built. SOLD! '72 GMC K25 4x4 468/4L80e/NP205 build thread http://67-72chevytrucks.com/vboard/s...23#post4324423 SOLD!'55 Chevy gasser 496/4spd build thread http://67-72chevytrucks.com/vboard/s...96#post4324396 |
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#9 |
Got Big Block?
Join Date: Apr 2000
Location: West Texas
Posts: 1,510
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glad it wasn't anything serious. I had an autometer mechanical gauge go bad. Actually the gauge was fine but the line got slightly crimped and caused the gauge to read inaccurate.
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"Experience is what you get when you didn't get what you wanted." |
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