I have a 2003 Ford Ranger. 123,000 miles.

Noticed over a week ago that I had a leak which was my coolant dripping out from under the coolant tank, just on the inside next to the passenger tire. Popped the hood and noticed the coolant was over an inch below the min. line so I filled it between the min and max - half water, half coolant. Next thing I noticed, after a 30 minute road trip...the overflow tank was bubbling to the top and was leaking through the bottom. Once the truck cooled, the again coolant fell over an inch below the minimum line as the rest had leaked out.

Took it in and they said it was a hose. Got the truck back and this time the same thing happened, except the coolant was now gushing out instead of dripping out of the bottom of my Ranger.

Took it in again and over the past week a new radiator, water pump, thermostat has been replaced, and the radiator has been flushed.

Picked my truck up again today and when I got my truck home I noticed coolant leaking through the bottom again right under the overflow tank. Popped the hood and noticed it was still bubbling to the top of the overflow tank. Once it cooled, the coolant again when back down an inch below the minimum line.

It's now sitting at the shop again and it's going to be looked at again tomorrow, but I'm looking to see if anyone here may have any idea what could possibly be wrong.

Any help? Thanks much! - Jennifer

Which motor do you have? Do you have a cap on the radiator and an overflow tank, or a pressurized reservoir tank with that cap on it?

If you have a cap on the radiator, has it been changed in all of this? I ask because if the cap is bad, it won't build proper pressure in the system before allowing it to flow into the overflow, and without proper pressure in the system, the coolant can boil, making the problem even worse, and reducing it's ability to cool the truck.


Just a thought.

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Hi! I have a 4 cylinder. As far as I know I just have the pressurized reservoir tank with a thick black cap on top of it. I went into Auto Zone and they sold me a silver metal radiator cap which I now have in my purse but it doesn't match the plastic cap I have so now I'm just really confused. Did they sell me the wrong thing? Thanks!

Yeah, I too have the 2.3, and yes you have the pressurized reservoir, so the cap VatoZone sold you is the wrong one.

Hmmm. With it bubbling out like that, I hate to say, it almost sounds like a leaking head gasket allowing combustion pressure into the cooling system.

Does it start bubbling right when you start it up, or does it take a while?

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If I take a short trip it won't necessarily bubble over unless it's a longer trip like 20-30 minutes.

I don't know if this helps at all but when I took it back to the shop and stopped the vehicle it started bubbling, but only after the engine was shut off. A few minutes later it was still bubbling then I turned on the vehicle again....sure enough the coolant was sucked back into the reservoir and was fine until I shut off the vehicle again and the bubbling began again.

They checked the engine, ran some sort of test to check for leaks, and they said the engine is working perfectly (knock on wood), so supposedly it's not a head gasket or anything. At least as far as they've said.

I'm just at such a loss here...

I'll take the cap back to Auto Zone tomorrow and try getting the right pressurized one instead. Maybe I'll take a drive back up to the shop and pop it on real fast, take it for a spin and see what happens.

Hahaha VatoZone...just caught that lol

That may help. other than the cap, if the head gasket is good, and with all the other parts you've replaced, I can't think of anything else at this time.

I'm surprised the shop decided to replace all those other expensive parts before the cap though. With you symptoms, thats the first thing they should have looked at, hoses second.

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I know...however, it wasn't too bad. The thermostat had never been replaced so it's good I did do that. The water pump was leaking a bit and they didn't charge me for the new radiator since they had my vehicle for a week and as I passed on renting a vehicle on their behalf. So that was nice of them.

As I was saying though, it only starts overflowing once I've shut off the vehicle. When I turn the vehicle right back on...the coolant is back down below the min. line and seems to be working just fine, until I shut it off again.

So when the truck starts, the coolant is down to normal. It stops, it overflows. It cools down, it's down to normal.

So strange...

If it were the engine, would it be overflowing while the truck is on too? Or could that be causing the fluctuation problem I'm describing?

Hmmm. There is another possibility. You could be running slightly lean, causing the engine to run hot. Then when you turn off the truck, the water stops moving, causing it to absorb all the extra heat off the motor and go beyond the limits of the radiator cap and thusly overflowing. Am I making sense here? I've seen it before, but on older carbureted vehicles.

I would expect it to throw a code, but it is possible that the sensors are right on that threshold, and not quite out of range. Things that could cause you to run lean, dirty MAF, clogged injectors, dirty fuel filter, bad O2 sensor.

Of those, I would change the fuel filter if it hasn't been done for a while (cheap), clean the MAF (practcally free) and throttle body while I was in there, and run a bottle of injector cleaner through the fuel (also cheap). Also might not be a bad idea to run some Seafoam through the intake to de-carbonize the engine.

All these together should make it run a bit better, but you would want to change the plugs after Seafoaming it, if you choose to do that. I don't know if that will help the situation, but it may be worth a shot.

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Man I wish I were a mechanic LOL.

Thanks for the insight - all definitely looking into or at least I will talk to them about it tomorrow to see!

Either way, I'll follow up here to let everyone know what happens. Thanks again!

I'm not a mechanic. I decided that field wasn't for me after working in a Hot Rod shop for 8 months. Working on other peoples cars all day makes me not want to work on mine. Lol. Keep us informed on how it turns out!

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my girls mustang was doing this so i purged her radiator hose and got all the air out of it, still noticed it so i replaced the intake manifold gasket kit and it's been fine since

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2003 v6 3.0
mods: blinker mod, hella 500ff's behind grille, blacked out grille, k&n intake, throttle body spacer, pioneer headunit and alpine sub w/ JL amp, 3" body lift, flowmaster super 40 dumped, police scanner, Red LED bars under dash

^^^ good idea, a leaking manifold could cause a lean condition, making the motor run hotter. Good way to check for that would be to get a can of carb cleaner, and with the motor running, spray it around the area where the manifold hits the head, and see if the idle changes when you spray.

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First off, I am not a mechanic either and I'm not trying to be the voice of doom here, but regardless of what they say at the dealer don't rule out the Head Gasket. My head gasket was damaged ever so slightly between the cylinders and I had similar symptoms (bubbling coolant tank, spilling all on the street--but not overheading AT FIRST). Never did I have any oil in the coolant, puffy white smoke, steam, or anything like that. Then, on a warm day, the temp gauge and the the heater started acting up. the temp gauge would fall all the way down to cold (heater blew cold) and then quickly flip up to 3/4 hot (it was overheating). The heater would go ice cold and then a blast of hot air like the heater core was clogged (but it wasn't)--and the temp gauge would flip down again. All along I was replacing themostats 180 deg stat, 195 stat, thermostats with the air hole w/o the air hole; then trying to burb the air out of the system; 3 radiator caps, radiator--you name it. Finally did the head gaskets (it had a couple of tiny cracks btw cylinder holes, and no more issues). They can be tricky is all I'm saying. I don't want it to overheat on you, and it put you down, but you may have to wait it out until the heater starts working hot/cold and it acts like it wants to run hot (just don't let it!).

Hi jennifer1207
I am having the exact same problems with my ranger 2.3L.
I would like a update on what was performed to solve the problem. Thanks in advance jplmain.