79 300 cooling problem
Freshman User
Joined: May 2001
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79 300 cooling problem
I have a 1979 f150 4wd with 300/6 with boiling over problem. It has 65000 original miles. The problem is it boils over everytime I drive it. It never gets hot not even to normal on the gage and the heater is always cold. I replaced the thermistat twice. The radator was damaged at one time and repaired so I replaced it with a new one. It still boils over and doesn't get hot. I just pulled the water pump off and it looks fine. Any ideas?
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Joined: Mar 2001
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79 300 cooling problem
>I have a 1979 f150 4wd with 300/6 with boiling over problem.
> It has 65000 original miles. The problem is it boils over
>everytime I drive it. It never gets hot not even to normal
>on the gage and the heater is always cold. I replaced the
>thermistat twice. The radator was damaged at one time and
>repaired so I replaced it with a new one. It still boils
>over and doesn't get hot. I just pulled the water pump off
>and it looks fine. Any ideas?
I assume you mean the pressure is always so great that the fluid "boils over" into the reseviour or just out...
You probably checked this already, but how about a new radiator cap?
Are you runnning a 50/50 mix with antifreeze?
Even more dumb of a question, not to insult you, but is the thermostat installed correctly?
Another idea maybe to look into replacing the coolant sending unit to assure your indicated temp is correct - it's in a bear of location to get to behind the exhaust manifold.
From what I've read here a FTE, most 300's run rather cool under normal conditions. Mine does...
> It has 65000 original miles. The problem is it boils over
>everytime I drive it. It never gets hot not even to normal
>on the gage and the heater is always cold. I replaced the
>thermistat twice. The radator was damaged at one time and
>repaired so I replaced it with a new one. It still boils
>over and doesn't get hot. I just pulled the water pump off
>and it looks fine. Any ideas?
I assume you mean the pressure is always so great that the fluid "boils over" into the reseviour or just out...
You probably checked this already, but how about a new radiator cap?
Are you runnning a 50/50 mix with antifreeze?
Even more dumb of a question, not to insult you, but is the thermostat installed correctly?
Another idea maybe to look into replacing the coolant sending unit to assure your indicated temp is correct - it's in a bear of location to get to behind the exhaust manifold.
From what I've read here a FTE, most 300's run rather cool under normal conditions. Mine does...
Thread Starter
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New User
Joined: Jan 2008
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Likes: 24
79 300 cooling problem
I would suggest that the sending unit has probably been installed with teflon tape which impedes the signal to the gauge.
Have you felt Both heater hoses for being hot to touch ?
Have you felt the upper & Lower rad hoses for temp ?
What is the temperature value of the thermostat you have installed?
Dennis
Please Don't Ask Me Any Tough Questions As:
"I'm Saving Up MY Memory For When I Develop Alzheimer's"
78 F-150 429CJ C6 ,Silver w/Explorer Pkge
641/2 Mustang,Pre-World's Fair Car #8092
64 Fairlane S/C waiting for a 390-4spd.
68-Mustang.Sunlit Gold 80,000 miles
Have you felt Both heater hoses for being hot to touch ?
Have you felt the upper & Lower rad hoses for temp ?
What is the temperature value of the thermostat you have installed?
Dennis
Please Don't Ask Me Any Tough Questions As:
"I'm Saving Up MY Memory For When I Develop Alzheimer's"
78 F-150 429CJ C6 ,Silver w/Explorer Pkge
641/2 Mustang,Pre-World's Fair Car #8092
64 Fairlane S/C waiting for a 390-4spd.
68-Mustang.Sunlit Gold 80,000 miles
Thread Starter
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New User
Joined: Jan 2008
Posts: 0
Likes: 24
79 300 cooling problem
Most people aren't aware that for sending units you need a special waterproof sealant that conducts electrical signal.
Most auto parts house have the correct sealant.
Teflon tape is a No,No.
https://www.ford-trucks.com/user_gallery/sizeimage.php?&photoid=768&.jpg
Dennis
Please Don't Ask Me Any Tough Questions As:
"I'm Saving Up MY Memory For When I Develop Alzheimer's"
78 F-150 429CJ C6 ,Silver w/Explorer Pkge
641/2 Mustang,Pre-World's Fair Car #8092
64 Fairlane S/C waiting for a 390-4spd.
68-Mustang.Sunlit Gold 80,000 miles
Most auto parts house have the correct sealant.
Teflon tape is a No,No.
https://www.ford-trucks.com/user_gallery/sizeimage.php?&photoid=768&.jpg
Dennis
Please Don't Ask Me Any Tough Questions As:
"I'm Saving Up MY Memory For When I Develop Alzheimer's"
78 F-150 429CJ C6 ,Silver w/Explorer Pkge
641/2 Mustang,Pre-World's Fair Car #8092
64 Fairlane S/C waiting for a 390-4spd.
68-Mustang.Sunlit Gold 80,000 miles
Moderator
Joined: Dec 2001
Posts: 22,436
Likes: 17
From: Louisville,Ky.
79 300 cooling problem
Sounds to me like Either A- you have a bad air pocket in the system or B- your waterpump impeller has wore out and you are not circulating any water. I have seen this happen several times . It won't show hot, And it has no heat. The water in the block starts to boil causing it to push out of the cap. My guess would be a worn out pump. I have also seen the impeller slipt on the shaft causing no circulation. 
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Fleet Owner
Joined: Jun 1999
Posts: 24,552
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From: Creedmoor, North Carolina
79 300 cooling problem
Jimmy, I am with you on this one, my thoughts are that the water isn't moving. Either a bad thermostat or water pump.
Hoss you could have that thermostat in backwards too. Check for a flow arrow and while you have it out, take it out for a run and see what happens then.
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John
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In the cool still quiet of night, you can hear chevies rusting away.
Hoss you could have that thermostat in backwards too. Check for a flow arrow and while you have it out, take it out for a run and see what happens then.
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John
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[link:www.ford-trucks.net/users/jowilker/NCFTE.html|NCFTO] North Carolina Ford Truck Owners Group
In the cool still quiet of night, you can hear chevies rusting away.
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Freshman User
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79 300 cooling problem
I tried two different new thermistats. I took the water pump off it looked fine. I don't think it is the sending unit because the heat or heater hoses or radiator hoses don't get very hot.
I just got another new cap going to try it this morning.
I just got another new cap going to try it this morning.
Postmaster
Joined: Jul 2001
Posts: 4,956
Likes: 10
From: MD
79 300 cooling problem
I see everyone has forgotten one important note:
Non coolant recovery system or coolant recovery system?!
If this truck has the non cooling recovery system, did you make sure water is NOT full when cold? It should be level just above the fins. Not full to the cap neck.
If this truck has the coolant recovery system, how does it look when overheated? Is it even with "HOT" mark? Or overflowing? Etc, etc.
But from the replies I've read here, it does look like your water pump took a dump.
Non coolant recovery system or coolant recovery system?!
If this truck has the non cooling recovery system, did you make sure water is NOT full when cold? It should be level just above the fins. Not full to the cap neck.
If this truck has the coolant recovery system, how does it look when overheated? Is it even with "HOT" mark? Or overflowing? Etc, etc.
But from the replies I've read here, it does look like your water pump took a dump.
Moderator
Joined: Dec 2001
Posts: 22,436
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From: Louisville,Ky.
79 300 cooling problem
Make sure that you get all of the air out of the system. Run the truck with the cap off, let it warm up to operating temp. It may puke alot of water out in the process. Watch for the thermostat to open, you should see some water movement across the top. If needed add more water until it is above the cores but leave some room for expansion. If it continues to build up pressure, you may have a headgasket leaking some compression into the cooling system.
Freshman User
Joined: May 2001
Posts: 27
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79 300 cooling problem
I give up. I replace the head gasket. Still the same thing. The engine runs cool but still builds up pressure. I guess the head or block might be cracked. I guess I will just run it and ad coolant every once in a while.
Postmaster
Joined: Apr 2000
Posts: 2,838
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From: SD
79 300 cooling problem
[font color=red size=2]It sounds like combustion pressure entering the cooling system, either through a head gasket (which you already changed) or a cracked block/head. The way I check for this is:
1. Remove belt from water pump, so it won't turn with engine running.
2. Disconnect upper radiator hose from engine. Remove thermostat and reinstall thermostat housing without thermostat.
3. Fill engine with water through the thermostat housing until TOTALLY full.
4. Run engine, look for air bubbles to appear in the water at the thermostat opening. The more air bubbles = the bigger the crack/leak.
Be sure to watch the temp guage, don't let it get too hot, because you have no water circulating. You should be able to run a totally cold engine 2-3 minutes without it getting too hot.
If you find air bubbles, then you have 2 options. Either tear it down and have each piece checked until you find the culprit. Or keep driving it, while you find or build a replacement motor. It's up to you.
Marty
1. Remove belt from water pump, so it won't turn with engine running.
2. Disconnect upper radiator hose from engine. Remove thermostat and reinstall thermostat housing without thermostat.
3. Fill engine with water through the thermostat housing until TOTALLY full.
4. Run engine, look for air bubbles to appear in the water at the thermostat opening. The more air bubbles = the bigger the crack/leak.
Be sure to watch the temp guage, don't let it get too hot, because you have no water circulating. You should be able to run a totally cold engine 2-3 minutes without it getting too hot.
If you find air bubbles, then you have 2 options. Either tear it down and have each piece checked until you find the culprit. Or keep driving it, while you find or build a replacement motor. It's up to you.
Marty
Senior User
Joined: Jan 2002
Posts: 255
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From: "tween the cotton and tob
79 300 cooling problem
ok... so pull the thermostat out. look and see if water is moving in the radiator. is the rad or engine hot? is it actually boiling over or just over pressurizing? Put a pressure tester on the radiator, pump it to system pressure (whatever the cap PSI is) and watch it. If it loses pressure and there are no visable leaks then its an internal leak, block , head etc. No leak down then you have abad water pump. make sure the WP impeller isnt spinning on the shaft. Let us know how ya made out!