Hi,
My ‘99 Ranger with 3.0 flex bought new now has 110,000 miles. No major problems. Just normal routine and wear and tear issues. Lately after a diy oil change, I found the coolant overflow tank was empty. Checked the radiator and found the level down just a little. I refilled the tank and checked it again after a month. The tank is again empty. I can see no visible coolant leak. I last changed the coolant and replaced all hoses 6 years ago. The temperature is always where it should be. The engine runs fine. Wondering if others have experienced this issue and what you found. Will appreciate your ideas. Thanks.

 

You have a leak after engine warms up, when system has pressure, and coolant is evaporating before it leaks to the ground

Reservoir is replacing the lost coolant on cool down

Simplest way to find it is to use a cooling system pressure tester when engine is cold
You can rent these
Its a rad cap with a hand pump and pressure gauge attached
You put it on the radiator and then pump it up to 18-20psi, normal is 16psi
Then wait and watch, engine and key OFF
Coolant will start to leak out and you can find the leak

Another way is to add a UV Dye to the coolant
Then use a UV light after driving it a few days to find the leak point
This method comes in a Kit with Dye and UV Flash light

UV Dye is safe to use in cooling systems and oil systems, like engine, power steering or transmissions
AC "freon" cans can also be bought that have this type of Dye added

 

Thanks for your suggestions. I was thinking that if I got the engine hot and then parked it and left the engine running, maybe I could check under the hood and underneath and see if I can spot a leak. Even if it is evaporating before it hits the ground, still might be able to see a little steam. Worth a try?

 

Yes, that would be the first thing to do

 

That’s where i’ll start. Will report back.

 

Finally had a chance to check for a leak yesterday after running the truck for quite a while to be sure engine was hot. Parked in the semi-dark garage and left the engine running for 10 minutes. All that time I spent looking in and under the engine compartment with a flashlight. No leaks seen. Didn’t even see any signs of anything that might have leaked previously. Turned the engine off and spent a few more minutes looking. Nothing. Put some cardboard under the engine and checked this morning. Not a drop of anything on the cardboard. Wondering if this could be intermittent leak. Suggestions?

 

You could always try just replacing your upper and lower coolant hoses, and it's almost always a good idea to put a fresh water pump in. Then you are just down to radiator, expansion tank and thermostat as potential culprits. Unless your head gasket / head is compromised.

When you check your oil, does it look "oily" or like a milkshake? If it looks like a milkshake, the coolant and oil are mixing and you have a problem in the head.

Good luck!

 

Rent a cooling system pressure tester now, and test when engine is cold, if its not dripping when hot its because it is evaporating

Does the radiator stay full to the top after full cool down?
It should, check it each morning

 

Hoses were replaced 6 years ago when I changed the antifreeze. They are in good shape. Expect the water pump and thermostat are ok because I don’t have overheating problems. Recently changed the oil and it looked normal. No sign of coolant. Going to do a pressure test on the system next. Thanks.

 

Will do the pressure test when I get a chance. Yes the radiator does stay full to the top. Will keep an eye on it.

 

Check the rubber line that runs from the rad cap to the over flow tank.
There are a number of places where it can chafe on the way to the tank.
Mine had a very small hole in it, not enough to show any signs of leaks, but enough where coolant would slowly evaporate over many weeks.
Yours is acting the same way.

 

If there is a leak in the system then it won't hold pressure, of course, pump it up to 20psi, it will slowly drop, and coolant will leak to the ground

If it doesn't drop then could be a crack in the Overflow/Recovery tank but I would expect that to be seen dripping on the ground from previous tests

 

Thanks for the tip. Will check it out.

 

Thanks. The recovery tank looks ok. Will do the pressure test next.

 

My 09' was doing the exact same thing and gradually starting losing up to a half gallon of coolant a week. Then I started seeing white cottage cheese looking buildup all over the underside of the truck in spray patterns (from when I was on the freeway.) Washed and cleaned it all off, sprayed it down and a couple of days later, cottage cheese was back in specific areas. This cottage cheese looking buildup is actually the hot coolant splattering and drying all over everything and is highly corrosive, if you have this make sure to wear gloves and clean off as much as u can from any engine parts, hoses, or electrical connections and wires and from underneath the truck.
The problem ended up being a bad water pump, and the thermostat housing was leaking through the plastic seams (which Motorcraft housings are Infamous for.) After being quoted $1150. from a local shop I decided to order all oem parts online myself and paid some idiot who half assed the parts he installed and ripped me off for labor. On top of that my radiator was completely bone dry a week later.

This time I took everything apart myself that he installed except for the water pump. I ended up having to repurchase another new thermostat, upper and lower housing, new temp sending unit, 2 clips, upper rad hose, and several oem bolts that he lost. upon inspecting the second brand new OEM Motorcraft lower thermostat housing I noticed the seams were already separating from the factory. After thorough research My savior ended up being an all aluminum thermostat housing I ordered from Jonathan Simms at Simms motorsports. Put everything back together checked for leaks, then performed a full cooling system flush, added new 50/50 gold and its been fine ever since. I even had the mechanic at the dealership do a pressure test yesterday, while they were checking my suspension and it passed.




Simms all aluminum thermostat housing is the way to go. beware of cheap knockoff versions on Amazon or eBay. This runs about $130 and Jonathan ships it out super fast.

 

WOW! All I can say is WOW! Thanks for the info. Now, after the fact, it would have been cheaper to just keep adding coolant I guess. I will be taking the truck in to a local shop for a lube job in a couple weeks and plan to have them do a system pressure test. While they have it on the lift, I will inspect the
underside and see if I see any “cottage cheese”. Will let you know what we find.

 

Forgot to mention that mine started doing all this at 107k miles and it never seemed to be overheating either. The gauge stayed in the exact same spot where it always goes in the middle once engine was warm, even when I noticed my radiator was completely bone dry it never went into the H.
I honestly don't even know how long I had been driving it like that before I had a gut feeling to check the coolant level.

 

Believe me it's not cheaper to keep adding antifreeze, I did that for about 2 months prior to finding out what the real problem was. I guess if you purchase the concentrated version and mix it yourself, is cheaper but I was buying the premixed and eventually using a whole jug a week. It's such a pain to have to lift the hood and refill a certain amount EVERY time you leave or arrive at a destination just to make sure you'll make it back. The local shop told me I could keep driving it and filling it as I was doing, which they didn't recommend but is do-able.

 

A link would be nice, the only "Simms motorsports" I can find is for motorcycles.
I did find a "Simmons Auto Sportz" that has the part.

 

Apologies, im new to the forum and wasnt sure if we're allowed to post links to other sites. You are correct its Simmons Auto Sportz. The owner is a super cool guy and will give any help needed for installing it or answer any questions u may have about it. It's totally worth the money and nobody else has manufactured one like his design only knock off attempts.