I have a 2003 Ford E-150 Service Van with 174000 miles. Started out thinking it was a blocked heater core due to lack of heat. But after having the heater core flushed at least 3 times with no help it was determined that the engine itself is not getting up to temp. Then the T-Stat was replaced 4 times with 3 different manufactures. (Delco, Stant, Motorcraft) all 195F. Nothing has helped. Except for this temperature issue the truck runs just fine.
Statistics after running for 20+ minutes.
Ambient Temp 30ºF
Internal Heat Air Temp maybe 80ºF
Temp Gauge (Middle/Normal)
Climbs from full bottom cold to middle in about 4 to 5 miles – or 5 to 6 minutes.
Top hose Warm 135ºF – Bottom Hose Cold 50º-70ºF
Top Hose easily squeezable (not pressurized)
Has been run with cap off reservoir to bleed off any air.
Heater in hose temp. about 135ºF
Heater out out temp. about 100ºF
Have replaced the water pump since we did not know if it was the issue. It was not, made no difference. The blend door and actuator have been checked as well as the heater core for blockage and all is in good order.
It seems that the coolant temp under run conditions is about 40º-50ºF lower than would be expected. All the while the temp gauge appears in normal range. Not that I am trusting the temp gauge but…
Blocked off radiator approximately 70% with some Coroplast sheets.
Drove 200 miles with morning temperature at about 35ºF
Temp Gauge was a frog hair higher than normal.
Inside air from vents reached about 75º - 85ºF Higher if fan was on low.
Stopped at about 60 miles and checked top hose. Was pressurized,
had a temperature of about 185º - 190ºF which is higher, maybe closer to normal.
Next day, removed Coroplast sheets ambient temp 40ºF Inside air from vents
reached about 75ºF Drove about 20 miles and checked top hose was not pressurized,
had a temperature of about 145º - 160ºF which is lower than previous day.
My question is: What could be causing this low engine coolant temperatures??
Except for my driving and temp checks using a infrared sensor and a multi-meter with a “K” temp probe all the work was completed by my local shop. They are good quality shop and have experienced tech’s. They are stumped as am I.
Anyone here have any suggestions on what to investigate??
Thanks in advance.