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#1 |
Registered User
![]() Join Date: Aug 2015
Location: Kansas City, Missouri
Posts: 61
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Cool at idle, gauge reads hot when driving?
Ever since I installed my 383 with this 292 cam with .501 lift my factory gauge shows it running hot after just driving down the block. I have a rad cap and it only shows about 150 but my gauge inside just keeps climbing but when I stop to idle it goes down. I have an aluminum radiator with duel cooling fans. I had a temp. ascending unit from and 86 installed in a port in the intake. My motor by the way is a 86 block. I today installed the correct temp. ascending unit for a 68 but I had to put it in the top of the water pump and it still does the same thing. Could it be a bad gauge? I have also been told that my 600 edelbrock performer is not enough carb. and may be running to lean so that might be why my gauge goes up when driving and down at idle. I have never heard this but im not ase certified mechanic either. I need help getting very frustrated and don't want to destroy my new motor. I really appreciate your guys opinions, it helps but this one has thrown me for a loop. Thanks.
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#2 |
laying low
![]() Join Date: Mar 2001
Location: Searcy, Ark. USA
Posts: 13,200
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Re: Cool at idle, gauge reads hot when driving?
It almost sounds like there is no thermostat letting the coolant flow too fast to cool off.
__________________
Boog 69 Chevy stepside, 358/T350, 4.11 posi, 4.5/4 drop, rallys, poboy driver primer is finer 91 Chevy sportside, Tahoe, Yukon & GMC Crewcab All GM..'nuff said. I stand for the flag and kneel at the cross |
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#3 |
Registered User
![]() Join Date: Aug 2015
Location: Kansas City, Missouri
Posts: 61
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Re: Cool at idle, gauge reads hot when driving?
Well I even installed a new thermostat a 180 and it still does the same thing. Im just at a total loss of what to do.
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#4 |
Registered User
Join Date: Nov 2014
Location: Southwest Kansas
Posts: 306
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Re: Cool at idle, gauge reads hot when driving?
When it's getting hotter while driving, in most cases it's because of clogged radiator or radiator too small. Just not enough heat exchange. More than once I have seen this happen with electric fans, sometimes switching back to stock fan clutch setup helps. I don't think it's your timing, it would run hot when idling, too. Same with running lean.
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'64 C10 LWB, 283, 5speed '68 C20 LWB, 327, 4speed '69 C20 Custom Camper Longhorn, 350, 4speed '72 C20 Cheyenne Super, 396, TH400 '66 C60, 292, 4speed |
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#5 |
Registered User
Join Date: Apr 2011
Location: Fairview Park, Ohio
Posts: 1,031
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Re: Cool at idle, gauge reads hot when driving?
First thing I would do is get an IR gun and get true temp at the T stat housing.
This way you can eliminate sending units and gauges and know for sure if it's actually getting too hot. I picked one up fro Amazon for $15 to check temps on boat exhaust manifolds. I use it for other things and more than I thought I would. Nice to have in the shop anyway. 2nd that noted here with electric fans. Report back.
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My build page http://67-72chevytrucks.com/vboard/s...d.php?t=764662 My cabinet building site http://www.cbcabinets.com |
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#6 |
Moderator
![]() Join Date: Jun 2017
Location: Cherryville, NC
Posts: 2,191
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Re: Cool at idle, gauge reads hot when driving?
New 383...great !
New radiator? 2 core,,,,3 core,,,4 core...? Electric fans...please check they are truing the correct way...must be pulling air thru radiator if mounted behind....what controls fan turn on and off? Shrouds? I usually get best results with factory fan clutch and factory shroud...and no electric fans... Check the wire running to the gauge...ground out the wire on the engine and power on the ignition...the gauge should read full hot...remove wire from being grounded out...gauge should return to cold... Is this truck air conditioned? What exhaust system ? New ? Post pics of where the sender unit is mounted.. Have fun... ![]() ![]() ![]() ![]() ![]() ![]() |
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#7 |
Registered User
![]() Join Date: Aug 2015
Location: Kansas City, Missouri
Posts: 61
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Re: Cool at idle, gauge reads hot when driving?
I have a new 3 core champion aluminum rad. with 2 11inch cooling fans. The gauge worked great with my old stock motor but i had the temp unit in the head. These old school 202 heads don't have that so I have had it in the intake and now in the top of the water pump both doing the same thing. All I have is the green wire hooked to the ascending unit. Should there be another wire and if so where? I have looked on the back of the gauge cluster and cannot find anything on the back of the temp gauge. FRUSTRATED?
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#8 |
laying low
![]() Join Date: Mar 2001
Location: Searcy, Ark. USA
Posts: 13,200
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Re: Cool at idle, gauge reads hot when driving?
There is only one green wire going to the temp sending unit.
__________________
Boog 69 Chevy stepside, 358/T350, 4.11 posi, 4.5/4 drop, rallys, poboy driver primer is finer 91 Chevy sportside, Tahoe, Yukon & GMC Crewcab All GM..'nuff said. I stand for the flag and kneel at the cross |
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#9 |
Moderator
![]() Join Date: Jun 2017
Location: Cherryville, NC
Posts: 2,191
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Re: Cool at idle, gauge reads hot when driving?
Only one wire is needed for the temp sender...should be green if I remember correctly.
Grab yourself an aftermarket capillary style temp gauge and fit it into the manifold port... Give the truck a run and compare the results...I suspect the gauge in the dash may be faulty... The best place for the temp switch is in that manifold port when running the older heads... ![]() ![]() ![]() |
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#10 | |
Old member
Join Date: Jan 2002
Location: Liberty, & Garden City S.C. , U.S.
Posts: 19,936
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![]() Quote:
For cooling: Rule of thumb. Cooling. 1,250 CFM for a 4-cylinder 2,000 CFM for a 6-cylinder 2,500 CFM for a 8-cylinder ![]()
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1971 LWB Custom, 6.0LS & 4L80E, Speedhut.com GPS speedometer & gauges with A/C. 20" Boss 338's Grey wheels 4 wheel disc brakes. My Driver Seeing the USA in a 71 ![]() Upstate SC GM Truck Club 2013,14 and 2016 Hot Rod Pour Tour http://upstategmtrucks.com/ Get out and drive the truck this summer and have some fun! It sucks not being able to hear! LWB trucks rule, if you don't think so measure your SWB! After talking to tech support at Air Lift I have found out that the kit I need is 60811. Per the measurements I gave them. Ride height of truck inside spring and inside diameter of springs. |
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#11 | |
Registered User
Join Date: May 2011
Location: mich
Posts: 655
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Re: Cool at idle, gauge reads hot when driving?
Quote:
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#12 |
Registered User
![]() Join Date: Aug 2015
Location: Kansas City, Missouri
Posts: 61
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Re: Cool at idle, gauge reads hot when driving?
Im wondering if it just isn't the gauge or the printed circuit either. Aussie do you mean ground out the sending unit wire to something then turn the switch on and it should go hot then unhook it and it should go back to cold? It has new vintage air but its doing this without even having it running. I have ram horn dual exhaust 2.5 inch. The thing that is weird with all of this is that the gauge worked perfect with my ole stock motor. Still frustrated. Thanks for the help guys keep it coming I'll get it figured out sometime.
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#13 |
Registered User
Join Date: Nov 2011
Location: Ontario, California
Posts: 65
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Re: Cool at idle, gauge reads hot when driving?
I had similar problem with my old Cadillac when I used an aftermarket temp sending unit. I the bought an OEM one, and the problem was solved.
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#14 |
Registered User
![]() Join Date: Feb 2013
Location: Spring Hill, Florida
Posts: 465
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Re: Cool at idle, gauge reads hot when driving?
I sounds like to me the wrong temp sender. new sender and old gauge read hot. i went through 3 senders from the parts store before I dug out the original and installed it. The original gauge runs at a different resistance. There is a company that is making the correct sender but I can't remember their name for the life of me.
when you pop the hood when it is reading hot on the gauge, does it really feel hot? can you touch the hose? is is the rad hot? there is a big difference between 180* and 230* when you pop the hood in my experience. |
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#15 | |
Post Whore
![]() Join Date: Feb 2016
Location: Portland Oregon
Posts: 11,086
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Re: Cool at idle, gauge reads hot when driving?
Quote:
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Thanks to Bob and Jeanie and everyone else at Superior Performance for all their great help. ![]() RIP Bob Parks. 1967 Burban (the WMB),1988 S10 Blazer (the Stink10 II),1969 GTO (the Goat), 1970 Javelin, 1952 F2 Ford OHC six 4X4, 29 Model A, 72 Firebird (the DBP Bird). 85 Alfa Romeo If it breaks I didn't want it in the first place The WMB repair thread http://67-72chevytrucks.com/vboard/s...d.php?t=698377 |
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#16 |
Registered User
Join Date: Apr 2015
Location: East Tn (In the heart of the Smoky Mtns)
Posts: 1,868
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Re: Cool at idle, gauge reads hot when driving?
Have you checked to see if you're running Lean on the Carb? A Lean condition at higher RPM will cause your problem too.
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#17 |
Registered User
Join Date: Nov 2011
Location: Ontario, California
Posts: 65
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Re: Cool at idle, gauge reads hot when driving?
I still think you have an incompatible sending unit. I had this issue with mine.
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#18 |
Registered User
![]() Join Date: Aug 2015
Location: Kansas City, Missouri
Posts: 61
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Re: Cool at idle, gauge reads hot when driving?
Well I'm running a Edelbrock 600 performer right now but I'm getting ready to buy a new Edelbrock 750. Hopefully that will help with being to lean.
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#19 |
Registered User
![]() Join Date: Aug 2015
Location: Kansas City, Missouri
Posts: 61
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Re: Cool at idle, gauge reads hot when driving?
Okay Aussie I will try that. I can't remember the cfm's on the fan but the aluminum rad and the fans are brand new also. I'll try Aussie's plan first and go from there. The factory gauge inside just keeps climbing but my buddy had one of those IR guns and its only reading about 160 on the thermo housing. I don't know very confusing. I'll check my cfm's on fans when I get a chance.
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