I have the 4.0 L V-6 and am having the same problems you describe.

• never overheats
• bubbles only after it's shut off
• rarely used coolant
• replaced the cap - didn't help
• pressure tested the radiator while it was running, and the pressure was climbing above 16 psi even when cold (the cap is rated @ 16 psi, so something is overpressurizing the cooling system.)
• the smell of coolant after it's been running awhile, yet no leaks
• no white smoke out the pipe

All of these point to a cracked cylinder head, or a blown head gasket. I did not perform a leak-down test or compression test, but I'm 99% sure it's the head or gasket.

I'm in the middle of tearing down the top half of the motor. I have the intake off and will pull the heads in the next day or two. I will post anything I find with mine.

Good luck !

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2000 XLT 4.0 L Auto Ext. Cab 98k miles

Its hard to say what it is exactly without looking at the problem

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http://www.threadbombing.com/details.php?image_id=1688

Removed the cylinder heads on mine today - it was a blown head gasket in the #6 cylinder. Head or block must be warped.

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2000 XLT 4.0 L Auto Ext. Cab 98k miles

Jennifer I just read this and I had the same problem. Water bubbling over.
1st I found my overflow bottle has a hairline crack in it near the bottom side towrds the fender over the wheel. My head gsket seemed fine and so did my raiator and my thermostat. But somehow I was bubbling over. I had one collasped hose I replaced that . still bubbling. I replced over flow bottle. (junk yard) then I took old hose held it in my hand long end away from fan and placed it in the fan while it was running it did not take much to stop fan. It should have wacked that hose wacky so I figured Fan clutch was tired and not doing correct rpm's to cool thngs down. replaced clutch and all is well once again. On the road again!! So total cost was hose 9.95 bottle 20 and fan clutch 60.00 =90.00 and I am not a mechanic. But I am learning. In your posts none of this was mentioned with the replacements you had done so I thought it might help you.

just letting you know that this thread is over a year old...

I just read through the whole thread and it contains some great info.

We know how to read, Crowd.

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2006 4.0 5 spd auto 4x4 Super Cab
BF Goodrich Commercial Traction T/A's
Royal Purple Throughout
Alpine Head Unit with some Infinity Noisy Stuff
NW Oregon

I would assume so since you are indeed on a forum that does not support the visually impaired. I wasnt knocking the info, just the fact that I hope that he doesnt expect the OP (jennifer to reply).

The coolant recovery bottles on those year 4cyl rangers are prone to crack and go bad, more than likely the recovery tank is cracked..

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98 ford ranger xlt ex cab 4.0 v6 auto trans

I have the same problem on 2002 Ranger with 2.3 Ltr engine. Everything appears normal, No coolant in oil, no white exhaust, but coolant tank backs up, bubbles and overflows a few minutes after engine turned off. First thing I did was replace coolant overflow tank cap...No help. Had coolant system pressure checked, and compression test with no problems detected. Mechanic put veghicle on computer and stated thet #3 cylinder indicated "slight" misfire. Anyone have any ideas? Could this still be a bad head gasket?

Haha the thread strikes again a year later...

This happens every year =-O

Good luck bud.

----Ford Ranger Owner----

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1993 ford ranger 3.0 v6

I would say head gasket. and if the shop is just replacing parts left and right but not fixing the problem, they probably don't know what they're doing. either that or they are doing what they should be doing which is finding the problem which is causing your truck to overheat. take it to a different shop.

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2011 Ranger XL Extended cab, 2x4, 2.3 L Duratec, Automatic, Mis-colored Leer camper shell, Ultragauge, LED plate bulbs, DDM "cree" reverse lights. Staying as stock as possible

The bubbling can come from a couple of things; it ain't normal.

Some are if you have a bad thermostat, fan clutch, water pump or ECT sensor.

But one overlooked thing can also be why. Water boils at 212 degrees F. If under pressure, it will raise the boiling point.
These systems are under pressure during normal use. If you have a leak in the overflow tank, or elsewhere, it can lower the pressure in the system and cause the water/coolant to boil a bit. Get the pressure back up (new overflow tank) and it will stop.