97 control trac 4wd clunk in rear end

[JohnyTyler]

I recently bought a 97 explorer sport w/ 90,000 miles. It seems to run great other than this issue. Sometimes when I accelerate in first/second gear (5 speed manual) I hear and feel a "clunk" coming from the rear end area. It feels to me like something is slipping. Stangely, this only occurs when the vehicle has been running for at least 15 minutes or so.....never does it when it's not warmed up. If I switch it from "auto" to "4wd HI" the problem seems to go away. I don't know much about 4wd systems as I have never owned one until now. Also.....when 4wd is engaged I hear a grinding noise near front wheels when turning. I don't know if these 2 issues are related....but if anyone has any ideas or suggestions I would greatly appreciate it.

Thanks!!

John

 

[Hartman]

The clunk could be a number of things. And you're generally not supposed to have the 4WD engaged on dry pavement. The grinding is your truck telling you to get the hell out of 4WD.

 

[Bronco638]

Sometimes when I accelerate in first/second gear (5 speed manual) I hear and feel a "clunk" coming from the rear end area.

Sounds like it could be the rear driveshaft u-joint. More in-depth, it could be broken pinion or ring gear teeth (??), but doubtful.

Also.....when 4wd is engaged I hear a grinding noise near front wheels when turning.

Like Hartman said (^^^), driving in 4 Hi on pavement isn't a good idea. You're hearing the front wheels trying to rotate the same speed and, if you hear the noise while turning, one tire is scrubbing ('grinding').

 

[JohnyTyler]

thanks for the responses guys, i will further investigate the rear u joint. Is there any thing i can do to confirm that the rear u joint is bad? there doesn't seem to be any play and nothing seems loose. Or would u suggest just changing it regardless and see what happens?

As far as the 4wd on dry pavement.....i was only attempting to check and see that the 4wd IS engaging.....sounds like you guys are saying that the grinding is not good but typical on dry pavement and nothing to worry about there.

Thanks again....I really appreciate the help!!

John

 

[96limitedX]

that sounds like your auto 4x4 engaging(sp?)..toatly normal. an if it goes away when you put it in 4x4 that sounds toatly noraml then. its nothing to worry about.

 

[JohnyTyler]

Well guys....I changed both u joints tonight....and they were both bad. not terrible....but when I got them off they did both have some play. It is definately better.....still "clunking" occasionally, but not nearly as bad. I did wonder if it could be the 4wd locking in. If so....something is still not right because there is no slipping going on....and it shouldn't lock in the fronts until there is some slippage if I understand it right. do you guys think it could be the sensor that tells the 4wd that there is slippage? If i can't get it to stop maybe I'll look into the brown wire mod......anyone ever try that?

 

[Bronco638]

Well, your 4WD system shouldn't be trying to engage at this time of year. I think it would have to detect spinning rear wheels before attempting to engage the transfer case.

As for the 'clunk' you continue to hear, if you've replaced the u-joints, the only other places to look would be in the differential or in the transmission. Is it possible that the previous owner installed some type of locker? Perhaps that's what you're hearing. Do you hear the noise after taking a corner (the locker unlocked going around the corner and then locked when you applied power)?

The Brown Wire Mod simply stops the transfer case from engaging. It most likely wouldn't resolve the 'clunk' issue which seems to come from the rear of the truck (according to you).

 

[JohnyTyler]

I don't know of any locker that was installed.....in fact i do not even know what that is. However, whether i'm going around corners or going straight does not seem to change a thing. It still occasionally clunks. and you kinda feel the truck lose power then gain it back.....causing the truck to lurch forward and back. almost like something is slipping. What about the clutch? would a worn clutch cause it to not engage all the way into gear?

Do you think it's possible that the diff. fluid needs to be changed? 90,000 miles and doesn't appear to be any leakage whatsoever back there. I'm not sure what i should get into next.....

thanks for the help
john

 

[Bronco638]

I don't know of any locker that was installed.....in fact i do not even know what that is.

A locker is part of the differential assembly that allows power to be transferred to both wheels of an axle. Based on one of your following comments, I'm going to exclude this as a possible problem.

...and you kinda feel the truck lose power then gain it back.....causing the truck to lurch forward and back. almost like something is slipping. What about the clutch? would a worn clutch cause it to not engage all the way into gear?

This is starting to sound like a slipping clutch. Either the clutch disc is worn out or the pressure plate is failing. Your tranny should be fully in gear because you have not heard any grinding. But, with the 'clunk' and lurch, it sounds more like the pressure plate. The pressure plate uses springs (and sometimes centrifugal force) to apply pressure to the clutch disc. This keeps the disc in contact with the flywheel which, in turn, keeps power to the transmission. So, if you're feeling a loss of power and hear a 'clunk', the plate may be failing to keep pressure on the clutch disc.
This is a relatively straightforward fix. If you're not up to the task, I would suggest using a known brand if you go with aftermarket parts (Luk comes to mind). There's nothing worse than a chattering clutch because of poor quality. Motorcraft will most likely be more expensive but then it's factory stuff. You might as well change the throw-out bearing while you're in there. I'm not sure if the clutch is hydraulic on the Explorer. If it is and the slave cylinder is not accessible from under the truck, consider replacing that, too. You may also need to have the flywheel resurfaced if the clutch disc is shot and has worn into the plate. It sounds intimidating but really isn't.

Do you think it's possible that the diff. fluid needs to be changed? 90,000 miles and doesn't appear to be any leakage whatsoever back there.

I would say no. 90K miles for gear lube is nothing. It wouldn't hurt to change it but this is not the source of your problem (as long as the fluid level is correct - up to the bottom of the fill hole in the axle housing).

 

[JohnyTyler]

Well , I hope you are right. I was planning on replacing the clutch anyway.....so hopefully that is the source of the prob. I've experienced a slipping auto transmission.....and when it slipped the motor would rev up like it was in nuetral for a second or two. My explorer doesn't seem to do that at all. In other words....I don't hear the truck rev up when it the problem occurs.....that being said do you still think it could be the clutch?

And yes it is a hydraulic clutch

 

[JohnyTyler]

Oh yeah....one more thing. The problem doesn't seem to occur when the truck is in 4hi.......is clutch still the potential culprit? ....or would the problem occur equally in 4wd and 2wd if it was the clutch......hmmmm....

i appreciate all your info

john

 

[Pain]

97 Explorer controle trac 4WD

I have the same type of issue with mine. I hear a clunk from the rear sounds like the Ujoint poping or something in the rear end. This started recently.
When I go to pull forward I dont lose any power or seem to be slipping in any way but if im coasting say 45 mph and the coast is lower that the pull of the gear im in i hear a whinning noise not like a sync or anything more like a loud power stearing pump but I know thats not the case.
When I try to go reverse I have to wait a bit for it to accept that its in it before I can backup but if I hit a bump it sounds like it kicks outta gear but the stick never moves.

This is the odd part. If I put it in 4wd hi or low it takes reverse every time without any complications at all as if it was new but when turning right in 4wd its as if something isnt locking there is a pop and something catches like something isnt going all the way in.

If anyone has or knows this issue and can give me a swift cheap resolution to the problem let me know before I sell it off and get something else!