are you losing antifreeze? If not i doubt that its a head gasket . If its a hotspot then its gotta be air . Mine didnt start till i changed the head on the drivers side i had a cracked head . You can do a test to see if any exhaust gasses are getting in the cooling system . Any garage should have the stuff to test that. Or you can goto napa & buy the tester yourself , its real simple to do. What they do is put this blue fluid in a tube & apply it on top of the radiator while the engine is running & if it turns green there are exhaust gasses in the cooling system. Does your truck ever overheat & spit out antifreeze ? have done mine & everthing is ok so im down to a waterpump or flush out the radiator & see if the helps . If no fix in those 2 then i guess its run it off a cliff & go get a new one .

 

No! Im not loosing a drop! And my truck never over heats at all. and doesnt spit antifreeze either. Im kinda scratching my head cuz it didnt thump all day today at all and was perfect! Idk I am gonna put a new heater core and radiator in anyways since im gonna keep the truck im ok with investing in it.

 

Introduced in '90 I have a 91 and as far as I know the 4.0 never was V belt.

 

Okay i found out for sure what the problem was and this is shocking! It never was in the cooling system. I had a bad power steering pump! it was loud as hell and started to shudder and stuff. It was bad and would take away from the power of the serpentine belt and make my waterpump cool unevenly, I bought some Lucas powere steering restorer. two bottles and two diffferent times after a couple days drained power steering fluid and replaced with Lucas power steering restorer. The loud pump quieted down and the thumping stopped the night i put the Lucas in. 4 days have gone by and no thumping and infact my ranger is even idling a lot smoother. So a good thing to do is before u go swapping out water pumps and stuff check ur components to see if there is some power being robbed from the belt from another component. One more thing also my belt tensioner is not jumping like it was before as well. So problem solved :-) Maybe a sticky would be good for this one since it hasnt been done yet hint hint!

 

Hmmm Incredible i thought i was getting robbed of power to the pump a while back so i bought a new belt . I was hearing a loud powersteering pump so the new belt quieted it somewhat , but its not totally quiet still. Ill give that a shot & see if that is indeed what the problem is . Heck i really dont rember the last time i checked the powersteering fluid . I have always suspected that either i had a bad tensioner or idle pully but was too hard headed to replace those first cause the wife bitches if i spend money & didnt fix the problem . But that makes prefect sense the belt is pulling fine at speed but i guess it slips when reves goto idle & it creates a poor flow . Thanks for the heads up ill check that tomorrow & try the lucas powersteering fluid & may go ahead & replace the tensioner pulley & the idle pully I rember having to change them a couple times on wifes mustang cause they were bad . Ford doesnt make the best powersteering pumps afterall .

 

yea that was the problem 100% I used a total of 2 bottles and it worked so good my power steering is now much quieter and no shudder when steering. And i agree the ford power steering pumps could def be better. But Lucas is such a great product im very happy with the results. All u need an uneven flow to cause the steam pockets and with the pump bogging down and robbing the power from the belt it did just that. I also have to say it idles soooo much better to perfect infact. Can u believe a power steering pump could cause all that? Let me know if it fixes ur problem ok? It fixed mine within minutes of pouring the lucas in. Just remember to take or draw out some old fluid first to make room!

 

Will do David gonna try just as soon as i get up in the morning .

 

just make sure when u put the lucas in it takes time to work so giove it time and if one dont work get another 1 but 1 is prolly good enough. after u put it in work the steering back and forth for 5 minutes and see how much the noise goes down.

 

David thanx for figuring this thing out . I went ahead & replaced the power steering pump as it was kinda hard to turn with the belt off , i know its not supposed to spin freely but this was really hard to turn and it squeaked as i turned it by hand . So far knock on wood i dont have any thumping going on but im still gonna replace the belt tensioning pulley cause the bearing is going bad in it too . So this thumping is a product of the power being robbed from the serpintine belt & creating a uneven flow thru the cooling system . Now my truck idles so much better & not irratic like before Again Thanx david for figuring this thing out

 

hey ur very welcome im just glad we figured it out and its been a while now and all is perfect here to... good job replacing the tensioner and belt thats was a very good idea.

 

Just a quick update the truck has no problem at all anymore since i have done this fix. I do plan on changing the pump tho since to me this was a temp fix. I wanna thank each and everyone who tried to help me here. pawpaw, rockledge and everyone thanks.

 

Wow, I have been having very similar issues with my Explorer 4.0L after my serpentine belt broke, I overheated, and then had to replace the belt and water pump. Since then the temperature gauge goes up and down between cold and 2/3 scale on the gauge once fully warmed up and I can hear the steam noises inside the vehicle and can actually feel the gurgling on the radiator hose by the thermostat neck. I was searching through forums trying to find an answer. Thank God I found this thread. I was ready to replace the radiator and get the special Ford water pump to try to fix the problem. I have noticed that my power steering pump is a little noisy and this would also explain the premature breakage of my serpentine belt. I have also replaced the tensioner and idler pulleys as they both seemed pretty worn and I've replaced the thermostat twice. The explorer has 170k on it. Now I will try the Lucas Oil treatment and see what happens. If it works I will try to spread the news about this fix.

 

Check for combustion gas in the cooling system, description could lead to an opinion of a blown head gasket.

 

Well I tried the Lucas Oil treatment with no luck. I also took out the radiator and had it checked for restrictions but it checked out OK. I'd suspect the head gasket leaking but the coolant stays clean and there is no bubbling going on in the reservoir when it's happening. I guess if the exhaust leaking into the coolant is a small enough leak that might not be noticeable. I just bought a thermostat from Ford ( a ripoff at $31.08 but made in Germany) to see if that makes a difference. If it's still doing it I guess I'll do the chemical test for exhaust in the coolant. If that comes back negative I don't know what else to do.

 

Prior to the clash-for-clunkers fiasco, scrap yards were loaded with wrecked Explorers and Rangers, most with perfectly-good engines. It was pretty easy to find a used 4.0L OHV that you could swap in. Nowadays....I don't know.

My gut feeling is the heads probably got too hot and warped and/or cracked. A failed head gasket could also be evident. That's why I would be thinking about a possible swap.