Clunk and err driveshaft question

[David Canfield]

I have searched the forum for the dreaded clunk but I have a question that I didn't see an answer to.

99 mercury mountaineer v8 AWD 200k

Bought this truck a few weeks ago and have done the following.

Front cv axles
Front wheel hubs
Front and rear shocks
Sway bar links.

This is the first time that I have done any of my own work so all of this is new to me.

It started out with a clunk only after going from reverse to drive or when getting on the gas a little. Last night I had a flat and after changing tire it was clunking multiple times not only under a load but when I hit the brakes.

On the rear drive shaft there is a boot up near the transfer case before the u-joint. If i grab the shaft in-between the u-joint and the rubber boot I get some lateral play. Is this normal? What exactly is underneath the rubber boot? Some type of joint?

Any help would be great as I am not looking to drop a ton more money on a truck that I have only driven a 200 miles.

I have had a few people look at my mountaineer and we have not found anything wrong with the u-joints.

 

[jremington59]

Is the tire that you replaced the flat with identical to the other three? If it's not, don't drive it or you'll destroy the viscous coupler. That could also have been where the noise was coming from. The AWD supposedly senses a difference in as little as 3/32 of an inch in any tire and will not work properly. Mine is so sensitive that when I replaced only 2 tires with the same size and brand as the other two, that were used, it sensed the difference and I ended up replacing all 4. There's no mistaking the howl it makes when the tires aren't the same.

 

[David Canfield]

What type of noise does it make when a tire is different? Is it a clunk noise? When I got the truck it had one different tire on the front. so I wonder if the vc was damaged from having one different tire on it.

How can it tell, if all the tires are the same size with similar tread?

 

[jremington59]

All the tires have to be the same size. If not the viscous coupler shifts power to the one it "senses" is slipping. If I recall correctly they told me it's a 60/40 ratio between the two axles and if the tires are smaller or larger they turn at a diff revolution than the others.

Mine made a loud humming/vibrating sound with a different tire. That's why I had to change all four. Some garages even have a machine that shaves tread off tires if they aren't wearing evenly. If you and whoever had the vehicle before you have been running it without even rubber there's a good chance the coupler has been damaged. Pull the front driveshaft and see what it feels like. I was also told by the tech that if the AWD is working correctly the vehicle will drift in park. If it doesn't, it's damaged.

 

[David Canfield]

Thanks for the input. All the tires were the same size but one on the front was a different brand with simular tread. After putting the spare with more aggresive tread the clunking was out of control. I only drove it about a block and a half never above 25 to get to my house. If I remove the front drive can I drive it to see if the noise is gone. If the noise is gone could that mean vc. Or other transfer case problems?

Thanks dave

 

[jremington59]

That would be the thing to do. If it's been a while since it's been out the front tourqu bolts can be stubborn if you live where they salt the roads.

There's 4 on the front universal and 6 regular bolts on the transfer case. Those are either 8 or 10 mm..... Takes about ten minutes on a lift, lol.

 

[David Canfield]

Okay.

So unlike the rear drive shaft there are bolts that need too come off the transfer case side? Since I do not have a lift, chock the rear wheels to avoid the drift with me under it?

Not sure if you can answer my other question regarding the rear drive shaft? Between the transfer case side ujoint and where the shaft gets bigger there is a rubber boot. I can grab that part of the shaft and it will move with some play side to side. What is under that boot? Should it have play? Can it be replaced if play is no good?

Thanks

Dave

 

[jremington59]

There are 6-10mm bolts holding it to the transfer case. There are 4 torques bit bolts on the front differential holding the universal joint. I can't remember the size of them.

I have a friend with a lift, but if not I'd find it easiest to probably jack it up in the front and put it on jack stands.

As for the rear drive shaft I'd say there's a cv under the rubber boot and shouldn't have much if any play. I'm not sure if that cv is replacable or not.

 

[David Canfield]

I worked both jobs today so i didn't have a chance to pull the shaft but i did look at it. I repaired the flat tire and took it for a little spin. It was better than the other night but the clunk was still there under heavier throttle. I will be looking at getting all new tires before i drive it anymore.

I did crawl under the car and noticed a few things ( may be normal ) It looks to me like the transfer case is tilted towards the back, sound right? Sorry for my improper use of terms but the front drive shaft back by the transfer case looks like it is at an angle going to the front diff. Meaning that it comes out of the transfer case pointing upwards but then is tilted down towards the diff. Also there is what looks like a silver ring that is coming out of the cone shaped part of the front drive shaft. To me this does not look normal, almost like it is coming apart from the inside. I am not sure what the transfer side of the shaft is called, not a u-joint but some type of ball or cv joint.

any ideas.

This site is awesome by the way, i have fixed major wiring issues from advice from this site and i just found my pass code for the out side keypad. SWEET

Thanks

Dave

 

[jremington59]

That little silver thing coming out is part of the CV that is falling apart. Mine was spitting pieces while I was waiting for the new one to get here. I should take a pic of my old one so people can laugh. Your slap that your hearing is most likely the front shaft shucking.

There's supposed to be a rubber boot covering the inside of the cv. That rots and the dirt, mud, salt and everything else gets in there and tears it apart. I'm guessing you can probably shake it up and down about an inch

 

[boominXplorer]

I bet that front driveshaft C/V joint is bad, the part that bolts up the the transfer case with 6 bolts. Remove the front driveshaft and go for a spin. You MUST use the E brake when in Park or your truck WILL ROLL on the slightest incline with the front driveshaft removed.

 

[David Canfield]

Had four new tires installed and still the same. Removed front driveshaft and truck drives like a dream, no clunk, no humming when on and off gas at highway speeds. Front shaft looks to be ok, all move free with no slop

Parked it on an incline and put bricks behind rear tires about a foot, came out this morning and truck krept back. Is it possible that my viscous coupler is ok? Could it be a chain problem or something else in transfer cas?

Used to clunk under light throttle and when making sharp turns.

 

[jremington59]

When I talked to the Ford rep he told me if it creeps it isn't shot, although there could be other problems. Let me ask you this. Have you changed the fluid in the T case? Or should I ask is it where it should be? It's my understanding that the coupler can either lose it's fluid or can seize up

I'd also add that when I first got mine and checked the front shaft it appeared good and tight. When checked a month later on a lift it appeared tight until moving the tires and then you could feel play in the CV. I t was like in certain positions it "grabbed" or whatever you might call it and didn't feel loose. That's why I asked if yours still has the factory sticker on it or if it has been replaced before. The chances of it being good at 175,000 aren't good. And if your TC is still good you can damage it by not running the front. At least according to the Ford Tech.

Let me ask you this. With the shaft in, and the wheel cranked, could the truck idle in a circle without binding?

 

[David Canfield]

I have been doing so much other work to it that this was the last and bigggest. ( at least that I know of) I have not checked the tc case fluid yet, is that the plug facing the rear shaft?

When it clunks it is very hard, can see the front shake. I have had it for two weeks, most in garage being worked on. When I first drove it it would only clunk when I realy got on it. Now it would clunk under light throttle. Three times turning sharp to the right I got a horrible grrinding/clunking, but it was like 30 clunks in a row real fast.

The shaft has a sticker and I would asume it is original, the shocks I replaced were original.

200k and most everything I have replaced looked original.

Motor and trans seam great and the money I have invested I do not want to give up on her. I like the truck alot so I will persist

 

[jremington59]

I find it hard to believe that CV joint in the front shaft is still functioning properly at 200,000 miles, but then again who the heck knows, lol.....

Here's what we do know. It clunked, but got worse with an off size tire being used, which leads to the TC/Shaft being the issue. It drifts in park which shows the VC is at least working properly.

When mine started clunking I packed grease into the CV and it quieted it down. So, why not remove the boot, pack the CV with grease and see if that stops or quiets the clunking. I don't see any other way of checking it other than buying a new shaft, which I'm still betting is what it needs.

Are you able to move the cv end in an out as it should? You should be able to pull that in and out a couple inches.

I got a lot of time into this Dave, lol. I got to see pics.

 

[Turdle]

I missed whether you got the new tires yet-but I will throw this in. Careful research will reveal that different brands of the same size tire, will have differing revolutions per mile. This will adversely affect the awd functions.

Also, the front drive shaft suggestions are dead on. Once you have it out you will see a small tear in the little rubber boot inside the cv cup I bet.

While you are taking the front drive shaft out-be sure to support the vehicle well on jack stands and chock the rear tires. Shake the truck to make sure it is securely raised.


Once the shaft is pulled the truck will not hold park. Keep this in mind.


OK, now that the front shaft is out, let's eliminate the front differential gearing-

Turn the front yoke, making sure it turns smoothly-and a wheel turns. Have someone hold the driver side front wheel from turning, and spin the yoke again. The passenger wheel should turn smoothly ( might be hard to turn but it should be smooth). Now hold the passenger wheel and repeat.

Then lower the car and go for a drive, see if the knocking goes away. Carry a brick for the wheel if you park it though, as it will roll on an incline without the front drive shaft in place.

.

 

[TBMounty50]

I'll back up the front shaft suggestions. I just went through the same thing.

 

[David Canfield]

Thanks, I appreciate. Your time and help. I did have four new tires and rims installed on Thursday, still had bad clunk. (Damage was already done)

I will more closely inspect shaft and take some pics. ( do I need to use a hosting servece for pics?)

Also being the clunk got way worse in the few miles I put on it, make me think shaft. Wouldn't the clunk stay the same? If the vc was seized

 

[jremington59]

Good advice Turdle.

OK Dave look at the CV end of the shaft.....

This CV is destroyed and there's nothing left to it. And without a load it didn't feel like there's play. But with a load it was shucking and banging badly. Sometimes it must have lined up right because it wouldn't vibrate and make noise. Other times it did.

If your boot is still there, Ford left no way of greasing it and it dried out years ago. If your boot is still intact, I hate to say this, but if you put a small slit in the boot and pumped grease in there I think you'll see the noise quiets down. There's really no way to undo the boot and seal it back up again.

I don't want you buying a shaft for nothing based on just my hunch and what I went through. But I had the same symptoms and this is what the CV looked like after being opened up.

 

[Turdle]

You can also get a grease injecting needle