Weird metal rattling sound

[ajm786]

This is a 1999 Oldsmobile Eighty Eight LS.

When you start the car, you can hear, coming from the driver side under the hood, a weird rattling sound. It sounds like a metal ball being shaken in a metal can. It's not loud, but it's clearly audible. More specifically, it sounds like it's coming around the area where the EGR valve is, but I can't be sure. The sound does NOT go away if the car is warmed up or cooled down. It remains constant when the car is turned on, that's all. I was thinking a ball bearing or something?

Any idea what may be causing this? The car drives perfectly fine, there's no warnings or CEL.

Thanks!

[ajm786]

Update.

I opened the valve covers. The gaskets were in excellent condition, as were the valve springs, and nothing was loose. It doesn't seem like this is the problem.

There is a big problem now. It got MUCH louder. Now, you can actually hear the car almost chugging, and when the car hits 2nd gear, you can hear a "flapping" sound coming from the engine bay.

I'm not exactly sure what the heck is causing this. Is it possible that the gasket for the cat converter needs to be changed and is leaking exhaust? Can an engine that needs an oil change make these kinds of sounds?

Help.

[maxwedge]

Diagnosing noises in this environment is nearly impossible. I would suggest a mechanic also listen to this for an onsite opinion, this may be trans related.

[ajm786]

Originally Posted by maxwedge

Diagnosing noises in this environment is nearly impossible. I would suggest a mechanic also listen to this for an onsite opinion, this may be trans related.

I'll take it into the local mechanic for this, although I don't trust him (he's screwed me over on a number of different occasions).

The problem is that I really don't have any good honest mechanics around where I live. The last 3 that I took the car too gave me bad info, and I ended up fixing the problem myself with you guys' help.

[ajm786]

Here's a video of how it sounds.

YouTube - noisy car

[moscow913]

I copied your youtube link to an email for my brother in the states. He's been a GM and Dodge mechanic for 25yrs or so. Max W is right, he also agreed that it's nearly impossible to diagnose the problem by sound.

However, since all he had was the video/sound, and I prompted him to give an opinion, he said this; "Sounds like it's about ready to toss a rod thru the block. I'd say it's lost a rod bearing like most uncared for 3800's."

In any event, good luck.

[ajm786]

Originally Posted by moscow913

I copied your youtube link to an email for my brother in the states. He's been a GM and Dodge mechanic for 25yrs or so. Max W is right, he also agreed that it's nearly impossible to diagnose the problem by sound.

However, since all he had was the video/sound, and I prompted him to give an opinion, he said this; "Sounds like it's about ready to toss a rod thru the block. I'd say it's lost a rod bearing like most uncared for 3800's."

In any event, good luck.

Does anyone know how does one replace a rod bearing? And what would be the proper way to go about diagnosing it?


And here's the question. When I got the car (about 4 months ago), I babied the car. I took good care of it, gave it the best quality fluids, brakes, tires, everything. So why all of a sudden this? And it only has 65K miles on it.

[moscow913]

Keep in mind that he could be wrong. Again, he wasn't real eager to give an opinion without a hands-on check.

Your best bet is to follow post #3 and find a mechanic who can check it out...and hope for the best. Good luck

[ajm786]

Update:

I ran 2 tests.

First, I checked the oil pan to see if there were any metal shards in it, which would mean there is a rod bearing that's spun. Absolutely NO metal in it.

Second, I turned the car on, then took off, one by one, each spark plug wire from the coil pack. I would replace each one after I took it off and listening to see if the sound went away.

This did not make any difference at all. The sound remained.

So am I in the clear regarding a spun rod bearing?

[ajm786]

Update:

I took it to the mechanic. As soon as he heard it, he said "harmonic balancer". He just so happened to have another car in the bay which was throwing a rod, and it sounded NOTHING like my car. Now I see what you guys are talking about a rod bearing going bad; the way it sounded was atrocious.

The mechanic then hooked up the OBD scanner, and there are no error codes; all readings came out normal. I asked him specifically about the oil pressure readings, and he said they all checked out normal (no dropping oil pressure).

He said 2 possibilities: crank position sensor (which I don't think, because the car has no problem with starting or anything like that), or the harmonic balancer.

What do you guys think?

[maxwedge]

Take the belt off and you can feel the outer hub on the balancer loose.

[ajm786]

Originally Posted by maxwedge

Take the belt off and you can feel the outer hub on the balancer loose.

I took the belt off. The outer hub doesn't seem loose. I can't move it, but I can jiggle it back and forth IF I give it a lot of force.

[maxwedge]

Back and forth rotating the engine? If so ok, if the outer part moves independently from the inner hub it is no good.

[MagicRat]

Originally Posted by maxwedge

Back and forth rotating the engine? If so ok, if the outer part moves independently from the inner hub it is no good.

Any kind of discernable harmonic balancer movement is very, very bad. It means that the balancer is no longer absorbing / damping vibration. The end result will be a broken crankshaft if the balancer is not replaced.

BTW, the previous owner of my '97 Cadillac had the same problem..... but the faulty balancer was not noisy, so he never noticed. The crank snapped at 7000 miles, when the engine was just idling.

[ajm786]

Ok guys, here's an update.

Sorry I had to do it at night, I have no garage and no other time to do it other than when I get home from work. So here goes:

I drained the oil and took off the oil pan, gasket, and exposed the pistons/rods from below. Inside the oil pan was no debris. There were a few tiny metallic flakes, which I believe came from the drain plug. You guys would know better than I would. But these metallic flakes were few and far between. Please note that the picture is slightly exaggerated (cell phone cam), and whoever installed the oil pan gasket last caked sealant ALL AROUND the gasket, so a lot of that fell in while I was trying to get it out; you can see that in the leftover oil in the oil pan.

http://img269.imageshack.us/img269/2323/0717090017.jpg

I could not discern any scoring. I grabbed the end of each piston rod to check for play; EACH ONE OF THEM (where I'm pointing) have a tiny bit of play, depending on what the position of the rod is. If the piston is up in the cylinder, there is almost no play. If the piston is down, there is a tiny bit of play. All of them, all 6 of them are like this. Is this normal?

http://img12.imageshack.us/i/0717090001.jpg/

I don't know about rod bearings, because I couldn't see them. I think they were under these "caps", covered with 2 bolts; either way, I could not get these caps off.

So I installed a new gasket, put it all back together, took some photos and some videos, and here I am.

I leave it to you guys to have a look at these pictures and tell me if you see anything amiss.

http://img43.imageshack.us/i/0716092359.jpg/
http://img189.imageshack.us/i/0717090000.jpg/
http://img43.imageshack.us/i/0717090009.jpg/
http://img190.imageshack.us/i/0717090010.jpg/
http://img12.imageshack.us/i/0717090011.jpg/
http://img198.imageshack.us/i/0717090013.jpg/


I fired up the car. Here is a video of the car when the engine is cool. As you can see, it's completely silent; exactly how I want it to be. After a few minutes of warming up is when the chugging starts.

YouTube - 07 17 09 0244

Any input after this would be great. Also, you guys are much help; thanks for putting up with me; I'm learning as I go along.