Odd rattle noise

[HeavyFoot]

I noticed this on Sunday... metallic rattle idling in gear. In neutral or park the RPM's go up and it goes away. Give it a little gas and bring the RPM's up to around 800 in gear, and it goes away. The noise isn't noticeable with the windows up and seems to be intermittent even at idle.

My theory is.. the engine bogs down a bit idling in gear and RPM drops to about 600 and the rattle is occurring because of that. RPM's hit 800-850ish.. and it goes away. Idle in neutral is about 800-850 and smooth.

Any ideas? I already checked the exhaust heat shields.. all seemed to be intact.

 

[wood1]

did you check if you have a baffle loose in the muffler?

 

[HeavyFoot]

That I haven't... I'll get under there and check it. I didn't have a chance to check the converters for loose catalyst either... I had a vic at work that had the catalyst come loose from the converter that sounded absolutely awful at idle. It was a more rock kicking around in a can sound than this though.

 

[fireball 440]

check your exhaust heat shields before anything.

 

[Kamel]

heat shield around the catalytic converter, i would bet money on it. the way you describe it is nearly identical to the way i described mine. i was just sure it was the transmission. even after inspecting i didn't think that was it, until i realized there are 2 heat shields, one on top and one on bottom. the one on bottom was fine. the one on top was the one rattling.

2 large hose clamps coupled together around the whole thing and tightened and not a peep since

 

[HeavyFoot]

Thanks, I'll give it a good look tomorrow. I'll be changing the trans filter and doing a fluid exchange so I'll be spending some quality time under it....

A mechanic friend suggested checking out the serp belt and tensioner as well.. so that gives me a few things to look for tomorrow.

 

[HeavyFoot]

It's not the exhaust. I'm thinking accessories.. it's only doing it with the engine under load(in gear). Serp belt needs replacing anyways.. so I'll do the tensioner at the same time.

 

[FIND]

Still sounds an awful lot like the heat shield around the cat or the front of the Y-pipe. The only other place to look would be the idler pulley, to see if the exhaust is contacting a body part somewhere that you missed or to bang REAL hard on a cool cat and see if you hear anything rattle, which would suggest your cat is deteriorating from the inside.

 

[HeavyFoot]

Did some fiddling today.. it's definitely the tensioner and the idler isn't helping either. Both have play in them.

I also ran it without the belt for a few seconds to see if the noise existed.. and it did not.

The frustrating part was, the parts store monkey couldn't get me the right tensioner.. he tried 3 times and all 3 times they were wrong. I'm going to order it from Rock Auto it looks like and get the Motorcraft part. The odd thing is the truck is a 93, but the tensioner appears to be from a 92.

 

[Maniak]

You can just change the bearing on the tensioner and the idler pulley, assuming its the bearing that is is bad and not just a weak tensioner.

The # on my bearing box, which just happens to be sitting at my computer desk for some odd reason is 6203.ee.j30 and is an SNR bearing..

~Mark

 

[HeavyFoot]

How do I change the bearing? That's definitely what's bad as spinning them by hand I feel grit. With the engine running the tensioner doesn't bounce so I am sure it's probably fine.

 

[Maniak]

Here is how I do it..

Take the center bolt off so the pulley/bearing come out in 1 piece. Put the pulley on a couple blocks of wood, and use a hammer and socket to knock out the old bearing.

I then use "Indian gasket shellac" stuff around the outside of the bearing and tap it into place. I use a socket AND the old bearing to push it in.

Viola, new bearing installed..

~Mark