6.9 Ford blowing off coolant

Matthew L · Apr 30, 2017

Hi everybody,
So I bought a 6.9 this morning and my dad and I drove it and checked about everything. It runs good and everything worked, but when he was driving it home, at about 65 mph it started blowing off coolant. It stopped after we let it idle for a little bit, and we put 1/2 gallon of coolant in it. It was alright for a while, then it started blowing a bit off, then it would stop, then it would start again on and off. Anybody have any ideas what might be the problem. Coolant temp gauge doesn't work, fixing that shortly. All I could think of is a thermostat or water pump going out. Matthew L

David G · Apr 30, 2017

I hate to think you got taken, but kind of a coincidence the gauge does not work.

I would think that getting hot at highway speeds might be plugged radiator, hope it is not internal.

Wisconsin Cowman · Apr 30, 2017

I would say bad head gasket. I would pressurize the cooling system for leaks.

Matthew L · Apr 30, 2017

Just to clarify it is coming out of a hose on the top of the radiator. Not to overflow tank, and not to engine. Can't think of the name of this hose for the life of me.

Janicholson · Apr 30, 2017

That hose must be connected to something. There could be the issue. Get a diagram of the cooling system. Lets all hope it is a mis-attached hose. Jim

MarkB_MI · May 1, 2017

Blown head gasket seems likely. Put a cooling system pressure tester on the radiator and fire it up. If the system pressure immediately goes through the roof, it has a blown head gasket.

Ragnarok · May 1, 2017

Sounds like it's getting hot. Usually if the head gasket is leaking it will smoke white from one bank or the other and start blowing coolant almost immediately upon startup.

Loose belts...worn pullys...stuck thermostat...bad waterpump...limed-up radiator...etc would be what I checked first.

I can tell you about my 92 F250 7.3 and thermostats. It had a bad habit of sticking thermostats...which usually would stick open. Stuck open thermostat wasn't too bad in the summer...but you could freeze to death in the winter! I quit buying the part store thermostats and got a genuine Ford/motorcraft part which pretty much solved it's issues.

Matthew L · May 1, 2017

Yeah if it idles, it is fine. It also doesn't blow white smoke, and the oil isn't milky, which leads me to believe that it is
something other than a head gasket. All the belts seem tight. I may flush the coolant this weekend. Then new thermostat. Matthew
L

M w J · May 1, 2017

Maybe simply a bad cap and when the thermostat opens it lets some out the overflow.

rlp in Co. · May 1, 2017

Stick the overflow tube in a can of water and start the motor. If you see bubbles the head gasket is blown.

6.9 Ford blowing off coolant

Matthew L

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David G

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Wisconsin Cowman

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Matthew L

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Janicholson

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MarkB_MI

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Ragnarok

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Matthew L

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M w J

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rlp in Co.

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