Cooling system issues.
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Junior User
Joined: May 2009
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From: rapid city, sd
Cooling system issues.
Hello all. I picked up this 72 f250 4x. When you start it, it had been getting a lot of pressure in upper radiator hose. I checked the basics and found the heater hoses hooked up backwards to everything I found on here. I reversed them and the problem seems to have went away. I read on one of the posts that the heater hoses provide a bypass to relieve pressure and I just want to verify that it does so I dont get out on the road and have problems. Thank you.
Fleet Owner
Joined: Dec 2009
Posts: 20,678
Likes: 82
From: NorCal
Hello all. I picked up this 72 f250 4x. When you start it, it had been getting a lot of pressure in upper radiator hose. I checked the basics and found the heater hoses hooked up backwards to everything I found on here. I reversed them and the problem seems to have went away. I read on one of the posts that the heater hoses provide a bypass to relieve pressure and I just want to verify that it does so I dont get out on the road and have problems. Thank you.
Ummmmm......What engine?
Fleet Owner
Joined: Dec 2009
Posts: 20,678
Likes: 82
From: NorCal
Thanks! 
The bypass hose is that lil 2-inch or so section of hose between the intake and the back of the water pump.
Another "bypass" is related to the carb.....Does your engine still have the carb de-icing plate underneath the carb??? If so, coolant exits out the back of the plate and connects to a "T" in the heater hose returning to the water pump as illustrated below:
Go to this post if you're thinking of deleting the carb de-icing plate because you will need a manifold fitting with a single port:
https://www.ford-trucks.com/forums/1...l#post13735633
The bypass hose is that lil 2-inch or so section of hose between the intake and the back of the water pump.
Another "bypass" is related to the carb.....Does your engine still have the carb de-icing plate underneath the carb??? If so, coolant exits out the back of the plate and connects to a "T" in the heater hose returning to the water pump as illustrated below:
Go to this post if you're thinking of deleting the carb de-icing plate because you will need a manifold fitting with a single port:
https://www.ford-trucks.com/forums/1...l#post13735633
Thread Starter
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Junior User
Joined: May 2009
Posts: 57
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From: rapid city, sd
Thanks!
The bypass hose is that lil 2-inch or so section of hose between the intake and the back of the water
pump.
Another "bypass" is related to the carb.....Does your
engine still have the carb de-icing plate underneath the carb??? If so, coolant exits out the back of the plate and connects to a "T" in the heater hose returning to the water pump as illustrated below:
Go to this post if you're thinking of deleting the carb de-icing plate because you will need a manifold fitting with a single port:
https://www.ford-trucks.com/forums/1...l#post13735633
The bypass hose is that lil 2-inch or so section of hose between the intake and the back of the water
pump.
Another "bypass" is related to the carb.....Does your
engine still have the carb de-icing plate underneath the carb??? If so, coolant exits out the back of the plate and connects to a "T" in the heater hose returning to the water pump as illustrated below:
Go to this post if you're thinking of deleting the carb de-icing plate because you will need a manifold fitting with a single port:
https://www.ford-trucks.com/forums/1...l#post13735633
Fleet Owner
Joined: Dec 2009
Posts: 20,678
Likes: 82
From: NorCal
'Could be a bad or wrong rad cap. It's supposed to bleed off air as the coolant warms up and expands.... as it cools down, it draws air (or coolant if ya got an overflow bottle) as a result of vacuum it creates.
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Junior User
Joined: May 2009
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From: rapid city, sd
I swapped caps earlier. Didnt seem to help. I have a tester to check for compression in cooling system and there is none. I also replaced the t stat today and flushed the cooling system out?
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Cargo Master
Joined: Sep 2005
Posts: 2,954
Likes: 64
OK, the cooling system does not care which way the water goes threw the heater, the only way that would be an issue is if you had a heater control valve that was closing because it was hooked up backwards. Since you didn't mention the valve I'm assuming you do not have one.
it's possible your t-stat was sticking and that caused the overheating, or you may have been air locked and it worked itself out.
I'd take it down the road and watch the gauge and see if anything looks strange.
if all is working correctly the needle will find it's happy place and stay there. If it is irractic let us know what it is doing.
it's possible your t-stat was sticking and that caused the overheating, or you may have been air locked and it worked itself out.
I'd take it down the road and watch the gauge and see if anything looks strange.
if all is working correctly the needle will find it's happy place and stay there. If it is irractic let us know what it is doing.
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Thread Starter
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Junior User
Joined: May 2009
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From: rapid city, sd
The truck has never over heated. Temp gauge warms up as it should to about 195 and t stat opens and truck runs 185 to 195 consistently. Im starting to think when I switched the heater hoses around, it backflushed something out. I do have the cable style temp selector valve in the right hand heater hose looking straight at firewall and ive had it open the whole time. Heater works great. Maybe I'm just being paranoid with the upper hose pressurizing but it just seems like its too much???
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Junior User
Joined: May 2009
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From: rapid city, sd
I could see where that is easily possible. Spring end is towards engine/ cone end to radiator. It does not have the little relief valve built into the ring of the t stat.
Fleet Owner
Joined: Dec 2009
Posts: 20,678
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From: NorCal
Drill a 1/8-inch hole on the T-stat flange to release trapped air and orient the hole at the 12 o'clock position upon installation.
Hotshot
Joined: Mar 2013
Posts: 14,255
Likes: 199
From: Phoenix, Az.
I'm thinkin' the coolant level wasn't high enough and it was trapped air and/or steam expanding the upper hose. 2X Hio on the hole in t-stat. Also make sure the coolant level is correct. Once it cools back down check the level again. You did buy a 13# cap, correct? How old are your radiator hoses? Radiator partially plugged?
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Junior User
Joined: May 2009
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From: rapid city, sd
Radiator hoses are a month old. Radiator rodded out and headers reset at that time as well. It is a 13# cap. Im going to drain it down now to drill the 1/8 inch hole. Ill let you guys know the outcome. Thanks again.
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Junior User
Joined: May 2009
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From: rapid city, sd
Drilled the 1/8 inch hole in top of t stat. Pressure is down a bunch. Takes quite a bit longer to get t stat to open. Runs 175-180 now. Im just going to run it for a while and see what happens. It dont look like its circulating all that much? I still need to do valve cover gaskets, check the valves, put on the new choke stove kit, and weld in the new floor boards. Think I'll drive it a while and flushthe coolant system again. Ill keep you all informed of any changes/issues. Thanks again for the help!