What is this stupid clanging?

[Blue85]

I have a new noise. It's almost like an old phone bell. It only happens when the truck is in gear and the rpm drops below 600. In park or driving around, everything is fine. It started when I put in the 2nd battery, which shouldn't be related, but I keep thinking that maybe I left a foreign object behind.

I can't find any evidence of anything loose underneath or shiny spots from stuff hitting. I pulled the inspection cover from the tranny and everything looks good up there. No appreciable dirt and no signs of a cracked flexplate. Banging on stuff underneath doesn't make the same noise except for the driveshafts.

Any ideas?

 

[ccarley]

Do you have the little heat shields like I do in between the exhaust manifolds and the plug wires? Mine rattle occasionally, and it sounds kind of like what you are describing.

With the engine off & cool, climb in there and if you see them pull at one & let it go to see if it's the same sound. I did that and found the source of the random "old fire bell" noise on mine.

Good luck...
Clay

 

[Blue85]

Do you have the little heat shields like I do in between the exhaust manifolds and the plug wires?

No.

There is a heat shield on the starter. I checked it out because I loosened it during my last project to get a nut that was stuck in there. I guess I should just remove it for troubleshooting.

I should also mention that the sound is there with the inspection cover removed.

 

[diesel4me]

Still have a catalitic converter??...seen lots of them lose a chunk of the catalyst and it rattles around inside at various RPM's--muffler baffles too,can rust away and end up vibrating inside the shell...loose mufler clamps can drive you batty too..
I had one "dinging" noise I traced to a hose clamp that vibrated against the water pump pulley on one engine,that made a very annoying noise only intermittently..

I have seen a few double walled exhaust pipes have the inner layer expand and contract and make some annoying sounds too...sounds like these are the ones you need to silence before attempting to sell a used vehicle--my friend deals with this crap daily after he buys auction cars & trucks for resale!..

 

[K5Jimmy]

If it's rotational and sounds like a bell, it's a Ujoint, if it's rotational and chirps like a bird, it's a Ujoint...sometimes a bad joint will ring going forward and chirp going in reverse...or vice versa. You Probably will not be able to wiggle the driveshaft to determine if the joint is bad. You can have one dry cup and the other 3 are enough to keep you from moving it by hand/pry bar.

If the noise is there when the truck is in gear and not moving...please disregard all of the above. I'm not a mechanic, I just work on stuff.

 

[Blue85]

Drivetrain is not moving at all when the noise happens. Currently no cat converters. I have banged all over the exhaust pipes and can't get any bell sound. I do think I should take another close look at the pulleys. What I didn't think of until now is that I changed the location of the alternator a little this weekend and installed a shorter belt. I don't "see" anything close, but who knows. Could belt misalignment set off a sound like that?

 

[owenst7]

So it's doing it when the engine is under load/in gear but the drivetrain isn't moving...?

Any chance the motor mount is allowing the engine to torque to the side and a pulley or something is contacting something? Not something that I normally think of but almost the same thing just recently came up when my buddy and I were trying to figure out a similar noise on his samurai.

 

[Blue85]

I lowered the idle speed last night until it would make the sound in Park. However, it would only do it for a second or two, never long enough to crawl underneath.

I checked clearance all around the pulleys and there's no way the engine can move enough to hit something. The alternator pulleys are within 1/4" of a bracket in a couple places.

I took the heat shield off the starter and re-attached it tightly. No change.

Could this noise be excited by pulley misalignment? I did move an alt. out about about 1/16" of an inch (there is a ring terminal behind it that used to be in front of it).

 

[Fordum]

Try tapping on a pulley while the engine is stopped to see if its the same sound. If it sounds like tapping on a driveshaft, then there are not a lot of things on a truck that have that same ring.
Pulleys are close.
When you say like an old phone, I think you are talking about a slow clanging sound instead of the brinnnng sound.

You are probably going to have to have some help. It sounds like you have gone as far listening as you are going to be able to by yourself.

Now you need to have someone in the truck to make it make the noise while you stand in different places to try to isolate what part of the truck its coming from.

Also, you need to watch the engine at least once to see if its rising up under load.
A broken engine mount can let the engine move several inches farther than you would expect. Which would let things hit that you would never expect to be able to.

Had a friend get "stuck" in the woods at the bottom of a small valley.
Good road, no mud, but the truck would not drive up the hill.
His engine mount had broken, and every time he started up, the engine would move so much under load it would pop the throttle linkage off the carb.

I am real hopeful that it is a pulley tapping something. Maybe on the back side where you cannot see it.
Double check that one you moved, and especially look for any wobble.

Otherwise, I'm afraid its in the torque converter or pump.
That is why you need to find out if its coming from the front or middle.

 

[Fred_M1010]

Check the clearance between the oil lines from your transmission and the engines oil pan.
Someone here had that problem not long ago, if I'm not mistaken.