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2002 Ford Explorer making grinding noise when coasting

jg101987

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I'm having a problem with my Explorer thats a little hard to describe. It started about 2 months ago (after it sat for about a year in my driveway, with startups just to keep it going and that battery charged)

I've been using it daily now, and there is a grinding noise that happens only when going over 30 or so mph. If I have my foot on the gas, I don't hear anything. But if I take my foot off the pedal, then I hear a noise which I can only describe as grinding. It only happens while coasting. Me and my mechanic friend took a look at it, and he noticed that the u-joints could use replacing, and the front of the driveshaft was a little loose.

His logic, which made sense to me at the time, was that the u-joints had a decent amount of play in them. When I hit the gas, they locked up and didn't make noise. But when I coast, it loosens up, and the play in there is what was causing the noise. We replaced everything, but the noise still happens.

Now we took another look, and he thinks that theres a little play near the transfer case, and the back end seemed a little loose (but not very) to him. Those were the only two apparent problems remaining, but he did say if it's neither of those, it has to be something in the transfer case (maybe the chain?)

I know a decent bit about cars, but this is way over my head. I know he can solve the problem (eventually) but I was just looking for some additional information. Maybe somebody else knows something or has experienced a similar problem. What is likely causing the problem/what should be replaced.

On a side note, I have recently noticed the grinding noise (VERY soft though) at highway speeds of 65 and over. I am guessing that it is related and has something to do with the fact that the car has so much inertia at that point, that its similar to coasting, which is why I am getting the grinding, just very light. I could be wrong.


On another side note, can anyone tell me, or point me towards some information about the way the 4wd works. I have 3 buttons that say 4WD Auto, 4WD High, and 4WD Low. I understand High and Low, but what exactly is Auto? Someone else on the web suggested I run it in each mode on a dirt road to see if something is just stuck. Could it really be that easy?

Thanks
 



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Mine has been doing this for a while now.. we took it to the shop yesterday and had the left front axle, and a wheel bearing replaced... didn't work... still making the noise. Our mechanic thinks the transfer case needs to be replaced and we'll be getting that done as soon as we can afford one. Auto Zone has them for 1,300 btw. (we have a baby on the way and just spent a huge chunk of savings getting our house painted and floors re-done)
 






I actually just got this problem fixed a few weeks ago, but forgot to post it here. I had a few people take a look at it before deciding to bring it down to the local ford dealer, where the service manager is a friend of mine. We didn't even get into the car to drive it before he told me the problem: The front and rear tires actually had a different tread design on them.

As he explained it to me, different tread patterns, whether they be on tires from the same manufacturer or not, cause different levels of traction. (in this case, i think the party selling the car at the auction I got mine from just replaced two of the tires on the rear, and not the front). The problem was that because there was more than one type of tread on the car, the computer sensed that two of the tires were "slipping" and engaging the clutch in the transfer case, which caused the noise. In reality there was just less traction on them because they were different tread patterns. I replaced the two tires for $200 bucks with ones that matched the fronts at a local tire shop, and the noise stopped that day.

Before you spend that money on a transfer case (which I almost did too) make sure all of your tires are exactly the same (manufacturer, size, and tread pattern). If they aren't then that may very likely be causing the problem. I lucked out and found two that EXACTLY matched the existing front ones (which had ~80% of their tread left), But if at all possible, I have learned that they should always be replaced in a full set of 4 whenever possible.


Whatever happens, I hope this helps and you can find a cheaper solution than another $1300. Good luck!
 






Your problem is 100% the transfer case. Look at my posts. I ended up doing a "frankenstein" thing on the transfer case because I did not want to pluck more than a 200.00 after the transmission nightmare but it works and costed me less than a 100.00 including the different front driveshaft. No more whirring or power drill noises after this. Eventually it will get worst and the noise will even starts at less than 30 mph if you don't take care of it. I also helped my neighbor did this on his 97 Ex weeks ago and he is tickled to death after only spending 60.00 and grilled me two 20 ounces TBone in the snow for 3 nights straight with all the beers I can handle :D, that's how happy he was. He was driving it for 6 months with the " power hammer drill" noises and it eventually starts at 10 mph as he lift off the pedal from coasting, it was 30 mph+ 4 months before so that's how I knew. I did not get any helps at all from anyone on the TC thing besides Glacier diary (excellent writeup) and don't want to spend anymore money so I went ahead and did it anyway since I was going to scrap the Ex if it didn't work since it was used as a spare. But luckily it did and that's why I'm sharing it with you all.:)
 






Your problem is 100% the transfer case.
............
He was driving it for 6 months with the " power hammer drill" noises and it eventually starts at 10 mph as he lift off the pedal from coasting, it was 30 mph+ 4 months before so that's how I knew.


While I do agree that the problem could be the transfer case, I would like to say that it isn't necessarily 100% the transfer case. I had the exact same problem that you described, and it was fixed by replacing 2 of the tires so all 4 matched.

To reiterate: 4 or 5 mechanics took a look at the car, and we ended up replacing the driveshaft and some universals, and I was only one step away from replacing the transfer case before I decided to take it to Ford (which I initially assumed would be the most expensive, but ironically they told me how to fix it for free). At Ford, they told me that it was the tires that were causing the problem (because of the different tread patterns).

Granted, a lot more people with this problem that I have seen end up having to replace the TC, but the Ford tech did tell me that the noise happening because of the tires being unmatched is actually very common, and he has seen countless cases where people who have an Explorer with unmatched tires get the noise and replace their TC, but come to them after cause it didn't solve it.



@shaddon: If you do end up having to replace the transfer case, I would suggest checking out junkyards or local mechanics first. When I did think I had to replace mine, I found a newer Explorer at a junkyard nearby with 40,000 or so miles on it, and the TC was perfectly good. They were going to sell it to me for $250 or 300 (don't remember which) and a guarantee that if it didn't work, they would take it back. You might be able to save a little bit of money there.
 






YES - it was a difference in tires on mine as well!!!

YES - it absolutely can be the tires causing this!!!

I had the exact same issue, and it turned out to be a difference in ONE TIRE on my Explorer. In short, I got a flat in the sidewall and a near by (close to the house) the tire shop replaced it with a used tire (to get me by) that was the same size, but had 4/32nd less tread depth and had a considerable different tread design than the other 3 on the vehicle (I had three all season road friendly design Michelins, and they put on an all terrain blocky style BFG). I notice the 'grinding' and feeling like it was sporadically going into/out of 4-wheel drive, and I got a whirring/semi-grinding noise periodically from what felt like the front end. I too thought, oh crap my transfer case went bad. I took it to a Ford garage that I trust and they test drove it. The guy came into the parking bay, got out with a big smile on his face (and I thought what the heck is he so happy about...), and said once he felt it, the first thing they do is check the tires/wheels, and he said the "spare" tire that was put on there is causing it - a combination of different tread and slight size - this is common on any Explorer with "Auto 4x4". I thought he was crazy, and told him thanks I'll look into it. I searched on line, found this forum and a few odd posts concerning this issue and some folks resolved it with tires, so I decided to purchase an identical used tire (to my other three) off of eBay with about the same tread depth. Once I received it, I had a reputable local tire shop install it (not the one that installed the spare originally) and the grinding/whirring/noise immediately went away!!!! The tire shop manager said they are aware of this issue with the "Auto 4x4" or AWD type Explorers and a few other vehicles and said that they see folks from time to time with this issue - when the tires and even tread don't match. Talked to Ford, and they said that technically there should be about a 1/2 inch tolerance in tire size and tread shouldn't matter unless they are totally different, but they agreed that they do see it happen. Folks, it's easy and cheap and takes two minutes to check your tires/sizes/tread before you run off to fix a TC - do the easy check first...
 






explorer transfer case noise

I just went throught this same thing on my sons 2002 explorer,my son had a flat,of course he put the spare on,thats when the noise started.only on decell or coasting,had people tell me it was the tranfer case going out,read a post or two and figured out it was the spare,I repaired his tire and put it back on, no more noise, aint the internet great,thanks to all the previous posters for sharing this info
Jimmy
 






While I do agree that the problem could be the transfer case, I would like to say that it isn't necessarily 100% the transfer case. I had the exact same problem that you described, and it was fixed by replacing 2 of the tires so all 4 matched.

To reiterate: 4 or 5 mechanics took a look at the car, and we ended up replacing the driveshaft and some universals, and I was only one step away from replacing the transfer case before I decided to take it to Ford (which I initially assumed would be the most expensive, but ironically they told me how to fix it for free). At Ford, they told me that it was the tires that were causing the problem (because of the different tread patterns).

Granted, a lot more people with this problem that I have seen end up having to replace the TC, but the Ford tech did tell me that the noise happening because of the tires being unmatched is actually very common, and he has seen countless cases where people who have an Explorer with unmatched tires get the noise and replace their TC, but come to them after cause it didn't solve it.



@shaddon: If you do end up having to replace the transfer case, I would suggest checking out junkyards or local mechanics first. When I did think I had to replace mine, I found a newer Explorer at a junkyard nearby with 40,000 or so miles on it, and the TC was perfectly good. They were going to sell it to me for $250 or 300 (don't remember which) and a guarantee that if it didn't work, they would take it back. You might be able to save a little bit of money there.

If it has auto 4x4,Its the tires
 






For what it's worth, an easy way to prove or disprove this would be by electronically disconnecting the clutch that engages the front axle. You see, our auto 4wd Explorers use an electric clutch to engage the front axle. It does this at 2 times: When you're in four High, it engages the front axle with a full duty cycle (95% I think actually). When you're in Auto 4wd (AND HERE'S THE KICKER), it engages the front end with a 5% duty cycle to the clutch. Not sure why they do this, but I think it has to do with preloading the front end, so if the truck decides to engage the 4wd instantly due to bad traction, there won't be slack in the drivetrain.

Anyway, a simple test to see if your noise goes away would be to disengage the front axle electrically. In other words, no more 5% duty cycle to the transfer case clutch. Look up "Brown Wire Mod" for some really interesting info about leaving the truck in 2wd mode all the time. There may be some gas milage, and some front axle wear that could be helped by doing this. I'm experimenting with it now.

In my 03, the 4wd control module is right behind the glove box. You can get to the connectors to the module by laying on your back and looking up. On the left side of the glove box, you'll see the approximately 5x6" Motorola 4wd control module. There are 2 wiring connectors to this module. The front connect is the one we want. Pull down the front connector, and look for a solid brown wire that's sort of all by itself in the connector, away from other pins. It's pinned into one of the four corners of the connector, and it's not of the 2 near the push-tab.

Pop off the red connector cover with a small flathead, and use a terminal tool to de-pin the brown wire. Pull the wire out of the harness and tape it off, and drive the truck. It will now not be able to engage the front axle no matter what. Any issues with the transfer case or front axle will now be gone.

Guys are doing this brown wire mod, which basically means they're cutting the brown wire and installing a switch inline to it. This gives them the ability to either run in pure 2wd mode, or in the stock auto 4wd mode.

In my truck, I have some drivetrain slack that is very problematic if i'm in 5th gear with the converter locked up, and suddenly let off the gas and then get back on it. There is a small clunk (probably minor rear ring & pinion slack) followed by a very large, nasty clunk. This is drivetrain slack in either my front axle or transfer case. I've been trying to figure it out since. I drained the fluid in the case, and it looks ok. The chain in the T-case appears to be "tight enough". So I drained the front axle fluid, and brakleened everything. What I'm finding is excessive wear in the spider gears, particularly the ones driven by the carrier pin.

The bad news is that you can't get the pin and gears out without pulling the differential out of the front axle. And you can't do that without pulling the front axle out of the truck. And once you do pull it out of the truck, you might need a dana differential spreader, which isn't cheap. Argh!
 






Si if I have The Grinding noise when coasting will doing the brown wire mod eliminate the noise?
 






Not so sure about that. But by temporarily disconnecting the brown wire from the harness, you can eliminate the connection to the front axle temporarily, and that may help you diagnose things.

Grinding when coasting is an odd problem. Have you checked your wheel bearings yet? The only thing I could think of that happens only on decel is that the ring & pinion mesh together on the other side of the ring gear tooth. If your gears were busted up, that could make that noise. If it's in an axle, you should be able to differentiate where it's coming from easier though.
 






I have the same problem on my 02 Explorer. I have 225,000 miles on it, my rear and front hubs are bad and I'm getting them replaced soon, it's had a new transmission installed at some point, new spider gears in the rear and differentials in the rear. All of my tires match and are relatively new.

I describe the problem as sounding like a diesel engine when I am holding my acceleration at any speed. There also might be a slight whistle which could be the front hubs that need replaced. But that sound that I hear when I am holding acceleration, sounds kind of like a diesel engine/slight gargle type of sound. If I let off of the gas pedal it stops, if I put the car in neutral and rev the engine it's not there, so I have no idea what it could be. I'm going to research this transfer case scenario though.

It almost seems like it only does it when I am holding a speed. Even with cruise control on I can still hear it. But it's not quite as bad if I am pressing down on the accelerator and gaining speed. It also seems like the faster I go and the faster the speed I hold the less I can hear it. It's still there though.

My hubs are so bad that I can't really hear anything because of the roar. I'm getting those replaced in a couple weeks.
 






There is a good writeup here on how to repair the rear wheel bearings. It's worth a read, even if you have somebody fix your car. The bottom line is that you can't hardly press out the rear bearings. They're in there so tight, you can break a press, or the spindle. I found that knocking out the bearings, then cutting thru most of the race helps weaken the race so you can bust it out with the press. Very tricky situation, and pressing the new bearings back in is also delicate. You can't press on the middle of the bearing, or you'll destroy or damage the new bearing. It has to be supported just right.

Try tapping on your catalytic converters with a rubber mallet to see if the converters are bad, or the heat shields have broken loose. In my case, after serious screwing around, I have determined that the noise comes from the transmission. Most likely the torque converter. It only makes the noise when the torque converter is not locked up. It never has gotten any worse, and I'm up to 150k so far.
 






Don't I know it. I don't have the means to press a bearing in propertly. I replaced the rear's once before and fouled one side up because my neighbor didn't have the perfect sleeve to press the bearing in, and we messed the bearing up. We got lucky on the opposite side. But the one we messed up quickly failed so I had a local shop do it. Getting that 3mo old Timkin beraring out broke their press. They used some AutoZone quality replacement, and now both sides (rear) have failed after 2yrs. One side Timkin, one side AutoZone.

I'm going to give Timkin another shot, but I don't think any brand is a sure thing. I'd be willing to do it myself, but for the time and effort, and the idea of not getting the bearing pressed in correctly, it's worth it to pay someone $300 to install my rear hubs if I provide the parts.

I sure hope whatever is making this sound isn't my tranny. I can't afford to have another tranny put in this truck!!
 






If anyone is interested, I'm going to elaborate on WHY tires do this to the transfer case.

This is the function of the transfer case, there is nothing wrong with a transfer that is doing this (cycling the clutch when tires are a different size).

As tires wear out, the diameter of the tire goes down. This effectively means that the final driving gearing goes down ever so slightly as your tires wear. A tire with a smaller diameter will make more revolutions per mile than one with a larger diameter (this is why putting larger aftermarket tires on your explorer lessens torque output at the wheels, it is "gearing up" the final drive ratio).

Your computer watches the wheel speeds, and tires with different diameters (worn out vs new) the computer assumes the wheels spinning faster, are slipping. Thus it modulates the clutch in an effort to prevent slippage.

It's actually a very good thing that the transfer case makes these noises causing the owner to fix it, because if it didn't then the tires would all be rotating at different speeds, which would cause excessive wear on either the differentials or the transfer case, which would be a much more expensive fix. If your front and rear wheels are connected, but the rears are spinning faster than the fronts (lower tread) then there is slippage somewhere in the drivetrain, and this slippage will cause damage (eventually).

In ANY AWD or FWD vehicle all of the tires must match to prevent damage to the drivetrain. In FWD or RWD vehicles you can maybe get away with mismatched tires (still shouldn't try it, it's dangerous for handling to have differences in wheels) AS LONG AS you have matching tires on the powered wheels. On a RWD, the rear tires should match, on FWD the fronts should match (to prevent differential damage).

Also, in any car, all tires really should match to keep the handling of the vehicle safe. Having different coefficients of friction on different wheels (be it from tires being worn, or from being a different make all together) can make for very unpredictable handling, but if you REALLY can't afford that, atleast follow these rules about matching on FWD & AWD, and matching driven wheels on FWD RWD, or else you'll pay much more to fix the differentials/transfer case.

EDIT- Holy dead thread! My bad I followed some link to get here and assumed it was new without checking the date x D.
 






I am having this noise problem which just started. I replaced my tires with new all matching about a month ago so I don't believe the tire remedy for mine. So any other ideas?
 






Rotated my tires today and after getting on the highway I noticed a loud clicking noise and some vibration ONLY when taking my foot off of the gas pedal. Once I began accelerating again it would go away immediately. After getting home I discovered that the lug nuts on one of the wheels were all very loose. I tightened them all up really good and the sound went away immediately. So check your lugs first.
 






I've had a problem with lug nuts coming loose on these aluminum wheels too, after having them off for service. Make sure when you put wheels back on, you go back after some miles and tighten them up again. Maybe more than once. You can also originally tighten them, loosen them, and tighten them up again. I've noticed you get more lugnut rotation doing that, so it probably helps, but retightening them is still recommended.

A bad wheel bearing sounds an awful lot like loud tire noise. Here's a test. Drive down the road and start swerving left and right. As you turn left, the weight of the vehicle shifts to the right wheels more. If there's a bad bearing on the right, this extra weight will make them growl more. Same for the other side. So left turn = right bearing check, and right turn = left bearing check.

After that, you just have to determine if it's front or rear.
 






Hello Everyone,

I hate to bring up an old thread, but I am having a problem that is similar to what the OP described. I get the same drilling when letting off the gas at hi speeds sometimes, and when shifting into Reverse sometimes. All 4 of my tires are the same thread (and brand), and (more or less) are worn evenly.

I had a vibration before when I had different thread tires on front and back, but this sound is different from what I had then. Do you suppose it could still be the tires?

I went to one transmission shop and they mentioned that a spline or something was worn and that it would require a remanufactured transfer case at a cost of about $1,200. I'm going to another shop this weekend for a second opinion, but the guy on the phone said it could be that "linkage needs adjustment".

Thanks,
 



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