Rattle getting louder

Back in July I posted about some noises I was hearing in the 3500-4500 RPM range. This has gotten louder over the past month. Is loudest in 4th gear, under either hard acceleration, or complete deceleration (foot off gas, car still in gear). When just cruising in this range in 4th gear, the noise is barely noticeable. Give it some gas, and the more gas you give it, the louder it gets. Same with letting off the gas. The noise SEEMS to be coming from under the car, but that speed its hard to tell.

I drained the transmission & differential oil last night looking for debris on the plug or any sign of metal, and found none. It all looks fine.

At this point, I did notice what appears to be an oil leak between the engine and transmission. I just had a new clutch kit put in back in July, and the rear main seal was replaced at that point, I'm wondering if the new seal has failed and somehow its all related?

Any opinions? I've attached a couple of blurry pics of the leak.

(I don't think this problem is related the valve lash question I had a couple of weeks ago)

Thanks,

-Tim

http://66.160.219.15/IMG_9433_edit.JPG
http://66.160.219.15/IMG_9432.JPG

I'd get the leak fix, but that's just me. ;)

When you say rattle could ya be a bit more specific. Is it a sheet metal rattle, or does it sound like something happening deep inside the engine.

Metallic in sound, but it is very fast. If you don't listen closely, it almost sounds like a hiss or a ssshhhhh. Doesn't sound hard or deep in the engine to me, just like a bearing rattling or something a little loose. I'm not familiar with deep engine bad sounds though, so its hard for me to say. A friend noted that it sounded like it could be the pressure plate, but I wouldn't know.

I'm in Richardson @ Glenville & Collins if anyone happens to want to come by and have a listen. :)

Also, I'm going to fix the leak. This was the first I'd noticed it. Just not sure where it is coming from. Rear main seal?

-Tim.

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Originally Posted by scorn001

Also, I'm going to fix the leak. This was the first I'd noticed it. Just not sure where it is coming from. Rear main seal?

-Tim.

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Is it oil or transmission fluid?? Those are about the only 2 fluids in that area of the car.

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Originally Posted by POS Racing

Is it oil or transmission fluid?? Those are about the only 2 fluids in that area of the car.

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Don't know. I'm loosing some oil I've noticed, about 1/2 quart every 1000-1500 miles, but the car has 161,000 miles on it. All I can say about the oil that is in the pic is that it doesn't seem to have the stench of transmission oil. I don't know how else I'd tell.

-Tim

Looks like earl to me! I suspect your "rattle" is either the heat shield above the cat, or the cat is starting to come apart......

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Originally Posted by MadMerv

Looks like earl to me! I suspect your "rattle" is either the heat shield above the cat, or the cat is starting to come apart......

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Brand new cat, less than 3000 miles on it, and the noise was present before the cat was swapped. When the original cat started to fail (PO420 code), I was positive I'd found the source of my rattle. No such luck. ::Rant::

Thanks,

-Tim

If it's not the cat, maybe it's the dog! Check the heat shield. One loose bolt, or stress crack and it will rattle.

Quote:

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Originally Posted by scorn001

All I can say about the oil that is in the pic is that it doesn't seem to have the stench of transmission oil. I don't know how else I'd tell.

-Tim

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That's how to tell the difference. That or oil analysis. The extreme pressure additives that make it gear oil have a very distinctive aroma. Once you've smelled it, you'll always recognize it.

Have you checked your muffler bearings??

I read on teh interweb that muffler bearing failure can make a rattling noise. And since it was on teh interweb it must be true!

::Clown::

Possibly on a tangent, but the noise you describe is very similar to what was occurring on my brothers 99. When you induce load on the prop shaft you would here a metal noise (engine braking, reverse acceleration). Normal driving the noise wasn't there or not noticeable.

http://forums.dfwmiata.com/showthread.php?t=10538

Check your propeller shaft (drive shaft from trans to differential). Not horrible to check, 4 bolts from the shaft to the diff hold it in. When we took his out, the noise was easily found as a bad bearing on the transmission side of the shaft.

Partsgroup.com came through with a replacement at a very reasonable cost.

oh, and the oil leak looks bad too ;)

Quote:

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Originally Posted by wrxmr2eater

Possibly on a tangent, but the noise you describe is very similar to what was occurring on my brothers 99. When you induce load on the prop shaft you would here a metal noise (engine braking, reverse acceleration). Normal driving the noise wasn't there or not noticeable.

http://forums.dfwmiata.com/showthread.php?t=10538

Check your propeller shaft (drive shaft from trans to differential). Not horrible to check, 4 bolts from the shaft to the diff hold it in. When we took his out, the noise was easily found as a bad bearings on the transmission side of the shaft.

Partsgroup.com came through with a replacement at a very reasonable cost.

oh, and the oil leak looks bad too ;)

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Are you talking about the u-joint? I'm not sure I know where a bearing would be in the propeller(drive) shaft. Is there something special about these propeller shafts that they have bearing on/in them other than the u-joints?

BTW, I'm taking it to Rogue for the oil leak. He thinks it might be that rear main leaking.

Thanks,

-Tim

Yes, sorry for the obscurity. I mean the bearing in the u-joint on the shaft. The bearing is not serviceable, you simply have to replace the shaft, unless you have already replaced it with a custom shaft.