Loosing coolant. Never smelled antifreeze. Thought that maybe had air in the block after changing radiator a few years ago. Filled the reservoir. But every three months or so have to add 1/2 gallon of water. I'm sure the mixture is way off now

 

"Three months" doesn't indicate anything, unless it's losing that much coolant when it's parked for three months. What DISTANCE are you driving in that time?

Best way to find a "phantom" leak is with a pressure test. You replace the radiator/reservoir cap with a special cap with a valve, and pump air under pressure into the system. This will cause the leak to manifest at room temperature, so it comes out as a liquid rather than steam. Being a '95, your truck might have a radiator cap rather than a reservoir cap. You should be able to borrow the tester from your FLAPS on their tool loan program.

'Course, it might be the radiator/reservoir cap itself.

 

6-7500 miles. I have replaced reservoir cap.

 

Some of the FLAPS pressure test kits don't include a test cap for an external reservoir like ours. (Baffling, since they've been around for 20+ years; my Saturn has the exact same style cap.) You may have to fashion your own. If you happened to save your old cap, you can drill a hole in it, and install a tire valve. May need to seal with RTV. Then you can just pump it up with a hand tire pump.

 

What's strange is, unlike any vehicle I have had, you can remove the cap, even the old one under pressure. If I did this in any of my other vehicles, you'd get hot antifreeze in your face. This is my first diesel.

 

There's always a risk that coolant will boil out when you remove the cap. But with a reservoir, you have a lot more air space above the coolant level, compared to an old-style cooling system with a radiator cap. So yeah, there's less risk. Is there at least some pressure release when you remove the cap when it's hot?

 

Makes sense, yes there is pressure

 

Went to ford dealer to get some of the proper antifreeze. Parts guy said 7.3 uses just plain 5.00 a gallon green antifreeze, no additive. Run plain water, doesn't matter

 

What the heck?!!! Is this a joke? That guy does not have a clue! You need an SCA additive/fleet coolant. That "parts" guy needs to be flogged and sent on his way. Use Fleet Charge Coolant and Distilled water. the coolant can be purchased at Napa.

 

Use Fleet Charge.

 

Not joking

 

^^^^ +1; and NO engine should run plain (aka tap) water, unless it's from a very soft water (surface water) source.

 

I drained old stuff out. Filled with water. Ran it till got hot. Drained radiator. Filled with distilled. Gonna do this with the distilled two more times. Then fill with the motorcraft coolant and additive

 

Are you pulling the block plugs when you drain it?

 

No sir.that's why I'm filling and draining. I'm on my third fill with distilled. After that was gonna drain and fill with coolant.