[02flatbedSD]

Got a 2002 7.3 that has a bit of a issue I’ve noticed since the weather has gotten warmer which is just a tiny amount of coolant coming out of the cap, doesn’t pool anywhere but you can clearly tell that there is a white streak coming down off the bottle, my coolant level seems to fluctuate ever since I replaced the bottle, sometimes it’s right at the max when cold and then when hot it is nearly at the cap, no bubbles in the coolant, no diesel or oil in coolant, engine oil is clean, runs great, not unusual smoking, Just concerned it’s in a cracked cup or good forbid a head gasket? On a 7.3? Surely not but who knows, any ideas? Going to replace the cap tomorrow and see what that does, could it be just overfilled?

 

[olddieseldude]

Don't cheap out on the cap. Use a good quality cap. I wonder if level issues could be a restriction between the radiator and engine that fills up the bottle.

 

[Oneof6]

I agree on the cap, get a new OEM 16PSI cap. The other, well what you have is a normal thermal expansion of the coolant condition.

 

[RT]

The "overfilled" theory may hold some water. (pun intended) My personal truck has a strange behavior. If I fill the tank to the cold fill mark - within a day it is down an inch. I can fill it up every day and by the next day, it is down an inch. If I leave it alone, it will stay at its "preferred level" indefinitely. I gave up trying to keep it "full" a decade ago.

 

[Greg687]

RT, mine does that exact same thing!

 

[Oneof6]

My coolant level was very predictable for years, fill it to max cold, it would expand in the recovery tank hot, up to almost the bottom of the tank cap. Then water pump leaks around the pump flange, I procrastinated on fixing it required me to top up frequently. Last year I changed that pump out and sealed it really good, new thermostat and it's housing, changed all hoses, new tank and cap and put new clamps on. Now it's back to it's predictable old thing, cold max expands to the same spot. Well, as long as I check it on a level surface.

 

[02flatbedSD]

Thanks for all you guys replies, hoping for the best, replaced cap today with a FoMoCo product, I guess time will tell now, I would think if a injector cup had cracked I would be overflowing with diesel in the coolant? Head gasket? Surly I would have some other nasty stuff going on but maybe it’s just the beginning?

 

[olddieseldude]

...I would think if a injector cup had cracked I would be overflowing with diesel in the coolant? Head gasket? Surly I would have some other nasty stuff going on but maybe it’s just the beginning?

From your description I would agree.

 

[ArcticDriver]

I seem to recall the original caps for the degas bottle (overflow reservoir) had a smaller spring in the cap and would get fatigued. At some point, Ford upgraded the spring and its noticeable when held for a side by side comparison.