2000 Dodge Caravan clutch burning smell

Tiny
GENSHIRA
  • MEMBER
  • 2000 DODGE CARAVAN
  • 3.3L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 110,500 MILES
A little back story. The van is a salvage van with a bent frame. The right side is lower than the left (from perspective of sitting in the car).
I recently had the motor mounts changed due to additional stress the bent frame had placed on it. Now, however when accelerating, and turning left there is a steady to rhythmic vibration noise that happens with the turn of the wheels (faster tires turn the faster the noise). The noise stops once acceleration is slowed. And it's a gradual stop. It's starting to happen upon acceleration even while going straight and almost never happens when turning right. It will never do it when coasting or slowing down. Usually a burning clutch smell accompanies the grind. And the burning smell is worse with heavier acceleration or hard turns to the left. There is no loss of power or control.
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Saturday, July 25th, 2015 AT 10:59 PM

9 Replies

Tiny
CARADIODOC
  • EXPERT
Ride height is determined by the coil spring, not the frame. If you're hearing a buzzing noise, that is almost always due to a noisy wheel bearing, and given the history, the vehicle's weight may have been placed on the bearing when the outer cv joint wasn't in place and torqued to specs. That will instantly make a wheel bearing noisy, but the style of bearing on your van almost always makes noise all the time. The older pressed-in style was known for becoming real quiet when you steered very slightly in the direction of the noisy bearing, such as when changing lanes. There's no burning smell associated with a noisy bearing though.

The first thing I would consider is supporting the van on jack stands with the lower control arms hanging down freely, remove the axle nuts, then see if you can push the threaded shafts of the outer cv joints toward the transmission. They will go in fairly hard, but you should be able to move them a good inch with heavy thumb pressure. If you can't move one of them, that half shaft is pushing on the engine and transmission.

There is a tool you might be able to borrow or rent from an auto parts store that borrows them called the "Chassis Ear". It is a set of six microphones, a switch box, and headphones. You clip the microphones to suspect points, then drive around while listening with the headphones. You can move the microphones around to zero in on the source of the noise. Be aware that many mechanics have never seen or even heard of this tool. Suspension and alignment mechanics use it to find rattles, squeaks, and other noises.
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Saturday, July 25th, 2015 AT 11:54 PM
Tiny
GENSHIRA
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Height: Agreed. I replaced the spring/shock pair on the right side and it helped a little at first but it has gone back down to what it was prior to replacing it. The frame is bent a little and on measuring the height displacement of the spring from inside the engine the left is about 3/4" and the right 1/2" but the height difference in the wheel well from top of tire to top of inside wheel well is about 2". Maybe it has become more angled which in affect would shorten that height?
Anyway, back to the noise. It hasn't always been there. It's progressive and after having it a year started about 2 months ago. It's just getting worse. I like your thoughts about the axle and though I'm unsure what you're referring to exactly I think it sounds promising. If the one half shaft is pushing in on the engine or transmission, how do I get it to stop pushing on it? Would the smell be a clutch thing from within the transmission making the smell?
I very much thank your speediness in answering, I did not expect that so thank you.
I'm sure it's me that just doesn't follow what you're saying but it sounds like I need to remove the wheel and all this in order to remove the 'axle nut'? By the way I replaced the sway bars and the inner and outer bearings.
Thanks again
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Sunday, July 26th, 2015 AT 1:42 PM
Tiny
CARADIODOC
  • EXPERT
You don't have to remove the entire wheel to remove the axle nuts unless they use a center cap that's bolted on from in back of the wheel. I don't think they used that style in 2000. If you can't push one of the shafts in by thumb pressure, the engine is not centered within the engine bay. You may also find one inner cv joint boot is stretched out quite a bit compared to the other one that is very compressed.

The engine is centered by the engine mounts. That is usually the job of the passenger side mount which has slotted holes to allow for some adjustment. The additional clue is the center mount will not be centered. One metal bracket bolts to the engine, and one bolts to the body. One of them should be centered within the other one. When the engine isn't centered properly, those two metal parts of the center mount may be rubbing on each other. They're supposed to be isolated by the rubber insulator in the middle.
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Monday, July 27th, 2015 AT 2:29 PM
Tiny
GENSHIRA
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This makes sense and explains a lot. The mounts were toast and I had my mechanic replace both of them. Since that time this has occurred (the sound and thus smell. The damage to the car must have shifted everything bad enough that the mounts are slowly giving way again causing additional shifting in the shaft you're referring to. I just went and looked and I see what you're referring to. The passenger side boot on the inside is MUCH shorter. I then compared the inset of the wheel on each side and lo and behold the passenger side wheel is literally pushed toward the engine by maybe an inch as opposed to the other side. Man, I don't think I can fix that. :-(
But that has got to be it.
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Monday, July 27th, 2015 AT 3:44 PM
Tiny
GENSHIRA
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Hmmm, if it's just about an inch can I shorten that shaft? I mean it's gotta be better and safer than trying to bend the whole system back out which would risk making it weaker. It's my wife's wheelchair van thus really important that it work even if just for awhile.
Thanks much friend.
Wayne
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Monday, July 27th, 2015 AT 3:49 PM
Tiny
CARADIODOC
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I have a friend with a body shop who specializes in rebuilding smashed one and two-year-old Chrysler products. Straitening sheet metal takes less time for him than it takes to get the vehicle mounted on the frame rack, Your van uses the Uni-body design which is much stronger than a full frame, as long as it isn't suffering from excessive rust. Pulling something back to where it was is not going to seriously weaken it. What you must watch for are all those little dents and dimples in the corners of the rolled-up sheet metal. Those form crumple zones and stress-relieving points. When someone welds on extra bracing, that will make that area stronger, which can be a bad thing. That means in another crash, the stresses are going to be transferred to some other area that is not supposed to collapse under a controlled condition.

In this case, sheet metal that is pulled straight is better than sheet metal that is not shaped properly to match what passed crash-testing. Also, since the lower control arms are attached to the cross member which is bolted to the sheet metal, shifted sheet metal will result in shifted lower ball joints. That will make both wheels tip the same way, to the left or right on top. That's the main alignment angle, called "camber". Camber on most Chrysler products is easily adjustable by loosening the two lower strut mounting bolts and pushing the wheel to specs. That will take care of correcting camber, but it doesn't address the underlying reason why it changed.

Camber has a real big impact on pulling to one side when you let go of the steering wheel. Besides being in specs for good tire wear, camber on both sides has to be equal. (We usually make the left wheel just a fuzz higher to create a slight pull to the left to offset "road crown". That's roads leaning to the right so water runs off).

Here's where the next clinker comes in that even a lot of inexperienced alignment mechanics aren't aware of. That is a non-adjustable angle called "steering axis inclination", (SAI). If you stand in front of the van and draw an imaginary line between the upper and lower steering pivots, the angle of that line must be exactly the same on both sides. No spec is given but a typical angle might be 28 degrees. On your van the upper steering pivot is the upper strut mount. The lower pivot is always the lower ball joint.

Now imagine the crash has caused the front cross member to move to the passenger side by half an inch. The right lower control arm and ball joint have moved to the right a half inch, and the wheel will be tipped in on top. The opposite happens on the left side. That ball joint moves to the right too, and the bottom of the wheel does the same thing. The top is tipped out too much. At first the glaring problem the mechanic would see is the camber is terribly out-of-specs, and he might try to correct that. If there's enough range to the adjustments on both sides, he might make camber look perfect on the computer screen, but SAI hasn't been corrected first. With such bad readings that he started with, most mechanics will know to look for the cause. That could be as simple as another mechanic just replaced the struts, or he needs to look for evidence of a crash. Some customers seem to think it's a good idea to keep crash information secret, but that isn't going to make correcting the problems any easier or faster. When the mechanic knows the vehicle was crashed, SAI is one of the first things he will look at.

Correcting unequal SAI is often as simple as loosening and shifting the cross member to one side. As a point of interest, GM front-wheel-drive cars have their engines and transmissions removed by removing that cross member, and a real lot of people don't understand how critical it is to mark it first so it can be put back exactly the same way. Moving to either side by as little as 1/16" will create a car that has extremely miserable handling and will dart left and right unpredictably when driving over normal bumps in the road. Readjusting camber won't fix that.

Chrysler uses a different type of bolt to hold their cross members to the body, and shifting to one side isn't possible, but that doesn't mean they're immune to bent sheet metal. If you have a printout from a recent alignment, SAI will be shown for both front wheels. All computers measure that automatically when the mechanic is performing other procedures. It must be equal on both sides, generally within 0.2 degrees. If you find considerably more than that, you will have already noticed less-than-ideal handling. The goal now is to see what it will take to shift the cross member so the two struts tip more or less until they're equal, then have camber readjusted. If you find the cross member has to be moved to the passenger side, that will push the ball joint and bottom of the spindle that way too. That will move the wheel bearing too, resulting in the right inner cv joint extending under its spring pressure.

Now that I shared all that, don't get overly-excited yet about inner cv joint boots that don't look the same. Chrysler buys their half shafts from two or three different suppliers. They all interchange, but they do that in case one factory goes on strike or can't keep up production. When you buy replacement joints or boots, the dealer will ask you for the seven or eight-digit part number on the yellow sticker on the shaft to be sure they get you the right parts. The only definite way to be sure neither joint is bottomed out is to see how far you can push the outer joint toward the engine. Each one should move about an inch. Remember to never have the vehicle's weight on the wheel bearing when the axle nut is loose or not torqued to specs. Most call for 180 foot pounds, but some are as high as 240 foot pounds.

I've never heard of anyone trying to change the length of a half shaft because that would be a method of covering up the underlying problem that is still going to be there. Drive shaft shops do custom work for special applications like limousines, but another problem with half shafts is they usually have some type vibration damping built into the hollow tubes, and that can't be duplicated after a completed shaft is cut apart.
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Monday, July 27th, 2015 AT 11:09 PM
Tiny
GENSHIRA
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Wow, that is a tremendous amount of information. Very thorough. That is great. Now, unfortunately my mechanic, though good is not that good. He knows it's a salvage vehicle. There's no other way I could have afforded a wheelchair van, lol.
Ok moving on.

Shorten: agreed. I just need to make it last as long as I can with a reasonable expense

Crumple: Fortunately there is no visible crumple BUT I can see where one side of the vehicle is lower than the other and not until I looked at it yesterday did I notice the wheel inset a little more on one side though I have done a 'backyard mechanic' alignment once myself in an attempt to make it work finally relenting and bringing it to my mechanic.
Moving things back into place: I think it may be cost prohibitive to do this the thorough way but then again the cost of another wheelchair vehicle. The painful thing is maybe I could put the money into it but there's no guarantee it will work and some other issue that we didn't see could creep up in putting it back.
Right now there is no big driving difficulty or pull, just that noise that is getting worse and the smell. The smell is diminishing but I fear what had been keeping the noise at bay may be running out buy being burnt up thus not as much smell. I just wish I knew where it was coming from. Since it's either in the tranny or engine, it can't be good either way. Replacing either or both of those would probably be more expensive than attempting the repair.
I definitely need to get someone with a good amount of experience to check this out.
I sincerely appreciate your assistance and I consider that I owe you one, or two. I am a computer tech that, well, knows how to test things, lets just say, and if you could use my assistance feel free to just ask.
Thank you
Wayne
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Tuesday, July 28th, 2015 AT 5:10 AM
Tiny
CARADIODOC
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Actually, I have a friend who does computer repairs for businesses, and we were working on an $8000.00 board last night for a half million dollar tree harvester. This is WAY out of my league, but a cable got pinched resulting in a surface-mount resistor getting blown off the board, and an 8-pin IC looks like it got bombed. I have a hot-air soldering station and can replace the parts, but the only way to get them is from another defective board, and then we have to hope nothing else got damaged down the line. We're trying to spend a few hundred dollars to save the guy having to buy a new $8000.00 board. I have my doubts, but they seem to appreciate my enthusiasm!
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Tuesday, July 28th, 2015 AT 6:16 PM
Tiny
GENSHIRA
  • MEMBER
Holy crap. Nah, my expertise is more what travels within the box, as in data forensics, penetration testing (ie ethical hacking) and the like but honestly that sounds more fun!
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Tuesday, July 28th, 2015 AT 7:31 PM

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