![]() |
Register or Log In To remove these advertisements. |
|
|
![]() |
|
Thread Tools | Display Modes |
![]() |
#1 |
Registered User
Join Date: Aug 2012
Location: St. Croix River Valley, WI
Posts: 795
|
190deg Therm causing temp gauge to read high?
Quick question. I just got the crate engine in my ‘70 up and running. The temp gauge is all but pegged even though a hand held laser therm shows the therm hosing to be in the 190-200deg Range. I got the correct sending unit from Lectro Limited (mounted In Drivers side head) and made sure the gauge cluster was properly grounded. I even put a ground pigtail on the backside of the gauge itself. Could the 190 deg therm be causing this higher reading on the gauge?
__________________
Meet "Old Roy": http://67-72chevytrucks.com/vboard/s...d.php?t=707801 |
![]() |
![]() |
![]() |
#2 |
Proprietor of Dale's Corner
![]() Join Date: Nov 2012
Location: Vacaville , CA
Posts: 16,100
|
Re: 190deg Therm causing temp gauge to read high?
I believe it can. If my memory serves me correctly the factory thermostat was165 degrees. Back in the day 210* was panic time.
__________________
"Some Days Chickens And Some Days Feathers" Dale XNGH ECV Sam Brannan 1004 R.I.P. 67ChevyRedneck R.I.P. Grumpy Old Man |
![]() |
![]() |
![]() |
#3 |
Registered User
Join Date: Mar 2006
Location: Malvern, PA
Posts: 951
|
Re: 190deg Therm causing temp gauge to read high?
I had similar issues using a 190 degree thermostat and standard off the shelf temperature sending unit. However, the issue was resolved by purchasing and installing a correctly calibrated temp sending unit for a 72 Chevy 350 from Lectric Limited.
Perhaps Lectric Limited (assuming that's who you purchased the temp sending unit from) could provide assistance if you call them and ask fornhelp. Also, to my understanding, these engines were designed to run with 190 degree thermostats. Running a lower than specified thermostat would mask the underlying issue.
__________________
Photo Gallery of 1972 K/5 Blazer CST |
![]() |
![]() |
![]() |
#4 |
Who Changed This?
![]() Join Date: Jan 2013
Location: Simi Valley, CA
Posts: 10,394
|
Re: 190deg Therm causing temp gauge to read high?
My truck was reading a pegged gauge with no symptoms of running hot. I put a different (mechanical) gauge in, and it runs about 190°, so I suspect that something could be wrong in your factory gauge circuit. Check you routing and see if the wire is grounded somewhere between the sender and the cab. Maybe something got pinched.
__________________
~Steven '70 Chevy 3/4T Longhorn CST 402/400/3.56 Custom Camper Simi Valley, CA |
![]() |
![]() |
![]() |
#5 |
Senior Member
![]() Join Date: Dec 2014
Location: Edmonton Alberta
Posts: 1,332
|
Re: 190deg Therm causing temp gauge to read high?
Shot in the dark: do you have a good ground strap from the block to the frame? Can't have too many grounds, especially when your sender is in the head.
__________________
DAVE Edmonton, Alberta 1959 Apache 1967 K20 1968 C20 1970 C10 1972 GMC 2500 1981 C10 Last edited by dagnabbitt; 07-24-2018 at 09:11 PM. |
![]() |
![]() |
![]() |
#6 |
laying low
![]() Join Date: Mar 2001
Location: Searcy, Ark. USA
Posts: 13,228
|
Re: 190deg Therm causing temp gauge to read high?
I believe the temp gauges and thermostats are tuned to each other. By that I mean a gauge is designed to be used with a certain * thermostat range to read properly. I ran into the same situation with an 85 Blazer some years ago. The gauge always registered normal until I put in a hotter thermostat. The temp gauge showed full hot in 3 minutes of idling. The engine was not hot but the gauge said it was. I put the stock thermostat back in and the gauge read right.
__________________
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 |
![]() |
![]() |
![]() |
#7 |
Senior Member
![]() Join Date: May 2010
Location: Wisconsin & Arizona
Posts: 4,844
|
Re: 190deg Therm causing temp gauge to read high?
Stock thermostat was 190*. The 190* thermostat was to reduce emissions. Therefore, it should not be a factor.
|
![]() |
![]() |
![]() |
#8 |
Senior Member
![]() Join Date: Aug 2004
Location: Centennial, CO
Posts: 2,948
|
Re: 190deg Therm causing temp gauge to read high?
I had the same problem, I changed the resistor on the back of the gauge to get the reading where I wanted it. I don’t remember what ohms value did the trick.
__________________
ClusterTruck: 68 C10 Bought in 89, wrecked in 03. Slow low $ rebuild started '17. 6.0 & TKO http://67-72chevytrucks.com/vboard/s...d.php?t=788602 93 K1500 Short Step, 350, NV4500, EBL flash ECU. Vortec heads & roller cam someday... 05 Jeep Wrangler Unlimited. 3” lift & 6-speed 02 E320 the insurance total “free car” 13 Tahoe LTZ |
![]() |
![]() |
![]() |
#9 |
Special Order
![]() ![]() Join Date: Nov 2004
Location: Mt Airy, MD
Posts: 85,859
|
Re: 190deg Therm causing temp gauge to read high?
190 is mighty close to 212, so I'd say the gauge is reading correctly. Your truck is close to boiling and that's what the gauge is reading, pegged = boiling/212. 190 is too high. I always run 180 and have no issues.
__________________
"BUILDING A BETTER WAY TO SERVE THE USA"......67/72......"The New Breed" GMC '67 C1500 Wideside Super Custom SWB: 327/M22/3.42 posi.........."The '67" (project) GMC '72 K2500 Wideside Sierra Custom Camper: 350/TH350/4.10 Power-Lok..."The '72" (rolling) Tim "Don't call me a redneck. I'm a rough cut country gentleman" R.I.P. ~ East Side Low Life ~ El Jay ~ 72BLUZ ~ Fasteddie69 ~ Ron586 ~ 67ChevyRedneck ~ Grumpy Old Man ~ |
![]() |
![]() |
![]() |
#10 |
Registered User
Join Date: May 2016
Location: Waverly, NE
Posts: 334
|
Re: 190deg Therm causing temp gauge to read high?
Water at sea level boils at 212 degrees F. Water mixed with anti-freeze and under pressure (our trucks should have at least a 15lb pressure cap) wouldn't boil until a much higher temperature is reached.
__________________
1965 Malibu SS L79 Restoration Page 1965 Two-Door Wagon Project Progress Page 2006 Pontiac GTO Preservation Project Rich Cummings |
![]() |
![]() |
![]() |
#11 |
Registered User
Join Date: Jul 2018
Location: Billings,Missouri
Posts: 25
|
Re: 190deg Therm causing temp gauge to read high?
I’ve seen a lot of new parts that are junk!! That new sending unit is probably made in good ole China. Just sayin
__________________
![]() 69 CST20 70 CST10 SWB |
![]() |
![]() |
![]() |
#12 |
Special Order
![]() ![]() Join Date: Nov 2004
Location: Mt Airy, MD
Posts: 85,859
|
Re: 190deg Therm causing temp gauge to read high?
You are correct. Regardless, 212 is only 22 degrees above 190 so gauge will read close to 212 before thermostat opens.
__________________
"BUILDING A BETTER WAY TO SERVE THE USA"......67/72......"The New Breed" GMC '67 C1500 Wideside Super Custom SWB: 327/M22/3.42 posi.........."The '67" (project) GMC '72 K2500 Wideside Sierra Custom Camper: 350/TH350/4.10 Power-Lok..."The '72" (rolling) Tim "Don't call me a redneck. I'm a rough cut country gentleman" R.I.P. ~ East Side Low Life ~ El Jay ~ 72BLUZ ~ Fasteddie69 ~ Ron586 ~ 67ChevyRedneck ~ Grumpy Old Man ~ |
![]() |
![]() |
![]() |
Bookmarks |
Thread Tools | |
Display Modes | |
|
|