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7.3 Cooling System Leak

779 Views 2 Replies 2 Participants Last post by  EricTowRig
I’ve searched and seen some similar problems but none that appear to be quite the same as mine. Here it goes.
2002 F250 7.3 240,000 miles, GTP38R turbo, single shot 160cc 30% injectors, new water pump 2-3 years ago as well as new hoses and thermostat. I don’t know if the motorcraft thermostat was used as the water pump failed when we were in the forest and work was done by a shop unknown to me. Fast forward to the recent issue.

I have had a coolant leak that seems to be coming from the hose ends of the cooling system. Thermostat housing, bottom of degas bottle, upper radiator connection. The cap on the degas bottle in new and no leak has come from there. It is the correct pressure rated cap. This has only occurred twice recently and only while towing up steep grades. I was not using a high horsepower tune (only my tow tunes). It has not done this any other time or under any other conditions.

I know one cause could be a blown head gasket but I’m never running high boost pressures while towing, usually in the mid 20 psi range max.

No steam coming from exhaust, no smell of coolant in the exhaust. No sign of contamination in oil. No sign of contamination in coolant. The truck has not overheated.

After I cleaned the coolant from the front of the engine yesterday I drove the truck around and got it hot and put it under high rpm (not towing) and could not create a leak. When I got home I checked around and noticed some very small bubbles coming from the upper radiator hose connection to the radiator. There was still a little bit of water, from washing the engine bay, around that connection and I could see and hear very small bubbles coming from this connection.

my question is how likely wouldthing issue be caused from the radiator hoses clamps being stock (21 years old) and simply not being tight enough to seal the hoses under higher loads? Also I’m curious if the thermostat is not completely opening could cause a pressure build up?

Thanks for any insight. I tried to provide as much detail as I could.

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I would think the hose clamps need to be snugged up.
mine look like what you describe.
I ordered new hoses and clamps.
also ordered a new thermostat housing ( known to leak ) & new stat

that is a project "real soon now"
Just did a pressure test on the coolant system and at 7 psi I can hear air coming from the hose ends. This is where I will start and replace all clamps.
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