Under heating issue

Tiny
GULLWING004
  • MEMBER
  • 2003 CADILLAC ESCALADE EXT
  • 6.0L
  • V8
  • 4WD
  • 200,000 MILES
Installed a champion three row radiator along with new water pump, thermostat, pressure cap, it will now not reach operating temperature. It will run at the hottest 170 setting off codes for thermostat not reaching temperature. I have tried six thermostats, no luck with any. So far the only solution seems to be partially blocking the overflow line from the radiator to the pressure tank, with that restricted everything seems to work perfectly. Radiator is hot hot on driver side, cool on passenger side return side and vehicle is at operating temperature. Anyone else had this type of problem? Also, it pressure tests fine.
Wednesday, November 1st, 2017 AT 12:49 PM

8 Replies

Tiny
WRENCHTECH
  • MECHANIC
  • 20,761 POSTS
I suspect your AC compressor is engaged, causing the cooling fans to run all the time. Check to see if that is the case.
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Wednesday, November 1st, 2017 AT 3:55 PM
Tiny
GULLWING004
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  • 8 POSTS
A/C is disconnected, fan clutch has been replaced as well.
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Wednesday, November 1st, 2017 AT 4:29 PM
Tiny
WRENCHTECH
  • MECHANIC
  • 20,761 POSTS
How and where are you testing the temperature?
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Wednesday, November 1st, 2017 AT 4:44 PM
Tiny
GULLWING004
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With a laser temperature gun at the outlet and on the heads, the scan tool (coolant temperature)(temperature sensor replaced as well).
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Wednesday, November 1st, 2017 AT 5:45 PM
Tiny
WRENCHTECH
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About the only thing I can tell you is it must be a run on bad thermostats. I would try a different brand. Delco if that is not what you are using now.

You might want to back flush the heater core with a garden hose too.
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Wednesday, November 1st, 2017 AT 5:48 PM
Tiny
GULLWING004
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  • 8 POSTS
Tried the expensive Delco, Stant, Moto rad, tried stock 187 and 195, the only thing that seems to do the trick is restricting that overflow line. Will that hurt anything?
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Wednesday, November 1st, 2017 AT 5:54 PM
Tiny
WRENCHTECH
  • MECHANIC
  • 20,761 POSTS
If you are talking about the overflow line that goes to the coolant reserve bottle, all that does is circulate the coolant in the bottle so I cannot see that having any major effect the on the temperature. It likely only prolongs the warm up a little. It is only circulating an additional half gallon of coolant. I just have a hard time believing it stays that cold with the thermostat completely closed. That just does not make any sense.
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Wednesday, November 1st, 2017 AT 6:07 PM
Tiny
GULLWING004
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I agree it does not make sense, but it is the only thing that has worked, will run a few hundred more miles and see.
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Wednesday, November 1st, 2017 AT 6:32 PM

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