New Radiator Problem
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Freshman User
Joined: Sep 2011
Posts: 31
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From: Central OR
New Radiator Problem
Just install a new radiator in my 1981 F250. Motor is a 300-6 cylinder. Problem is the temp gauge doesn't go to the normal range like it should. I can run it at fast idle for up to a half hour and it only shows just above cold.
Installed new hoses, thermostat, thermostat housing. Thought maybe the new tstat was bad, so reinstalled old one as it worked fine. Still no change. Heater hoses get warm, upper hose gets hot, but lower hose stays cool.
Any ideas what the issue could be?
thanks
Installed new hoses, thermostat, thermostat housing. Thought maybe the new tstat was bad, so reinstalled old one as it worked fine. Still no change. Heater hoses get warm, upper hose gets hot, but lower hose stays cool.
Any ideas what the issue could be?
thanks
Lead Driver
Joined: Dec 2012
Posts: 7,877
Likes: 49
From: Tennessee
New radiator = better heat transfer . You are cooling the engine better . Lack of heat in the cab ? Plugged heater core , improper heater controls . Are you running the proper Thermostat ? What is the ambient temp. in your area ? Many aspects to consider ...
Lead Driver
Joined: Dec 2012
Posts: 7,877
Likes: 49
From: Tennessee
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Freshman User
Joined: Sep 2011
Posts: 31
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From: Central OR
I thought about the new radiator transferring heat better. The heater worked fine before, nothing changed with heater controls, 195 degree t stat, same temp as it was before. Air temp around 50 degrees.
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What thermostat? My factory gauge is right on C when the aftermarket gauge hits 160 degrees. Really should be running a 195 and that will put it on R or M of NORMAL if the gauge is working correctly.
pedant
Joined: Jan 2008
Posts: 23,576
Likes: 40
From: EXTREME southwest CT
The heater core loop is always bypassing the thermostat in every Ford I know.
You should get heat before the thermostat ever opens.
I've never had problems with an airbound heater core, but then I don't have an I-6 either.
If the heater core hoses only "get warm" and "the upper rad hose gets hot" you have a restriction in the heater core.
Maybe dislodged some sludge when you swapped out the radiator?
Try disconnecting the heater hoses and backflushing with a garden hose.
Borrow or buy a non-contact IR thermometer.
(mine was ~$20 and reads -50 to 1,300*F)
Shoot the water neck, aka thermostat housing.
This should give you a *real number* to compare to the gauge.
More than likely your old radiator was not cooling the engine properly and what you thought was "normal" was -in fact- very hot.
My truck always reads just above the "O" in normal.
Ground the temp sender wire to the block and watch the swing.
Try a new sender.
Check that the ICVR is giving the correct voltage.
What made you change your radiator?
You should get heat before the thermostat ever opens.
I've never had problems with an airbound heater core, but then I don't have an I-6 either.
If the heater core hoses only "get warm" and "the upper rad hose gets hot" you have a restriction in the heater core.
Maybe dislodged some sludge when you swapped out the radiator?
Try disconnecting the heater hoses and backflushing with a garden hose.
Borrow or buy a non-contact IR thermometer.
(mine was ~$20 and reads -50 to 1,300*F)
Shoot the water neck, aka thermostat housing.
This should give you a *real number* to compare to the gauge.
More than likely your old radiator was not cooling the engine properly and what you thought was "normal" was -in fact- very hot.
My truck always reads just above the "O" in normal.
Ground the temp sender wire to the block and watch the swing.
Try a new sender.
Check that the ICVR is giving the correct voltage.
What made you change your radiator?