AnNoYiNg RaTtLes

Visitor # 20073 since 19.SEP.2001

AnNoYiNg RaTtLeS:

I've found and fixed many rattles in my pickup, only to find once the louder one is gone, I now hear a less loud one. I thought I might share some of the places I've found rattles on the off chance someone else has a similar situation. Also, if anyone has tracked a rattle source down that I've not mentioned, I'd love to hear from you. It seems the diesel engine and its inherent high vibration must contribute a lot to this problem. However, I've usually found noise making bits in places other than the engine.

1. I once had a terrible metal-on-metal banging sound on the driver's side when hitting bumps, like gravel washboard. It sounded just horrible. I finally opened the drivers side door and found the bottom of the window opener was just sitting on the bottom of the door. The passenger side was encased in a piece of tubing. A section of heater hose over the metal and this was fixed. I also noticed the little piece of felt had fallen off where the the door latch rod crosses over the sheet metal of the door, so re-glued that in place.
2. With this loud noise gone, I noticed I still had a rattle when hitting bumps. I used a rubber mallet to bang on part of the vehicle and found if I hit the front of the driver's side tire, I could cause the sound. It turns out, the metal shield behind the disc brake had one (of three) bolts missing. Two-thirds of it was unsupported and it would give a good metal-on-metal rattle when hit. It was also a bit deformed so, I eventually cut out enough metal on the front to get it off the hub, flattened the inner ring out, then put it back on with some brake anti-squeal compound and three bolts (w/ LockTite). It's solid as a rock now.
3. So I hit the road (and some good bumps) and there is something else rattling now, quieter than before, but its still there. This time I can't reproduce it when stationary, but...
4. When I'm in gear and accelerating, there is a small RPM range where I get a resonating rattle. A little history:
   1. I had replaced the front engine mount bushing several years ago and at the time noticed that it seemed to sit too far in front of the engine.
   2. Then I had the engine swapped out a year ago.
   3. Then I thought perhaps the front rubber bushing was shot again so I thought I'd try a polyurethane one! This turned out to be a BAD idea, but that's another story.
   4. In the meantime, I found one of two allen bolts holding the front motor mount arm to the starter was completely loose. Could this be the source of the rattle?
   5. So I put some LockTite on both bolts and tightened them both down. At the same time, I shimmed the motor mount back until the bushing seated deeply into the front cup. All this work done and guess what, these's a different rattle now.
5. So the RPM range where the rattle occurs is now much narrower than before and it seems to be coming from the same place as the bump rattle, so I may be getting close to finding this bugger. I suspect is may be in the exhaust system.
   1. This rattle is HISTORY. It turned out the cam belt was just a bit loose. The section that runs up front the crankshaft to the tensioner would vibrate at certain RPMs causing the noise. Just tightened it a bit and viola, no rattle!
6. After correcting my driver's side door alignment, I began to notice a rattle that seems to be coming from inside the door, right by my ear. I've had the door panel off a few times and have yet to cure the problem.
   1. Update: It turned out that while the door was out of alignment, the latch wore out the plastic layer on the latch pin because it rubbed it so hard each time the door was closed. After re-aligning the door, the latch was no longer in contact with the pin and the latch would rattle around on the pin. I picked up some 1/2" heat shrink tubing, just large enough to slip over the latch pin. I shrunk two pieces of tubing to cushion the pin and the rattle is now history!
7. After replacing the rubber suspension bushings with polyurethane, I think I have triggered a few new rattles behind the dash. I need to get back there and check for loose parts (and fix a few loose connections) one of these weekends.
8. Latest noise sounded like a bearing getting ready to seize up new the timing belt at around idle. After tearing into it, it seemed to be coming from the alternator and sure enough, the pulley retaining nut had loosened a bit, allowing the fan blade assembly to vibrate at slow speeds, making a terrible screeching noise that disappeared as RPMs increased. Torquing it back down solved this problem.
   1. I thought I'd take this time to share my simple belt tightening technique. I use a long board (1x4 about 4' long) and a nylon strap loop around under the alternator and around the board, one end of which is on the passenger strut tower. Then, lift the other end of the board, pulling on the strap which applies tension to the alternator belt. While holding the desired tension with one hand, tighten the retaining nuts on the bracket.
   2. A variation on this is to use a HiLift jack (or other tall bumper jack) to lift the end of the lever board. I use this for the A/C compressor which is tougher to adjust the belt tension than the alternator..

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