Horrible noise--still making it

My very first post here was about this same sound, and I still haven't been able to find the cause. My fist guess was motor mounts, and that’s what many here suggested, but I checked them and checked motor play and they seem to be fine. Also, now that I’ve heard the sound more, it doesn’t sound like engine rattle to me.

Then, I thought it was the power steering belt because it was rather loose from when I replaced the pump. However, after replacing the water pump, timing belt, and drive belts and tightening everything, it still makes the sound.

This is the best way I can describe it: When the engine is under high torque, such as accelerating in a high gear at lower RPMs or when going up a hill, the car makes a sound that reminds me of a metal chain rattling around. It does not make the sound when coasting and usually not when slowly accelerating. However, sometimes it makes the sound much more often and much louder than other days, and I haven’t been able to figure out what makes the sound happen more or less—maybe weather or something.

Anyway, the car seems to run perfectly, but this sound is driving me crazy because it is so loud and sounds like the engine is falling apart.
Facts about my car if it helps: 1986 GT Hatchback, about 131K miles, new water pump, timing belt, drive belts, power steering pump (from a junkyard), and a lot of other recent maintenance.

Soooo… anyone have any idea what could be making this horrible noise???

 

it's an automatic

 

Haven't checked that yet; sounds like a good place to start. Is it easy to remove and check?

BTW, I doubt it's anywhere near the muffler... sounds like it's from up front.

 

Sounds like a plan... I'll probably give that a shot this weekend.

 

I checked the heat shields and nothing was loose. I also banged around on the pipe with a rubber mallet to see if I could hear anything-- nothing.

I was thinking I could remove the cat to check the inside of the pipe-- it's nothing more than a couple bolts, right? No gaskets? Also, do you guys think that would tell me anything?

 

It's a 2-SE engine, and it makes the noise at any RPM, but only if there is a significant torque load on the engine, such as heavy acceleration or going up hills. Also, the noise is not consistent-- sometimes it is very loud, sometimes you can't even hear it when flooring it (unusual but occasionally).

 

It sounds kind of like a bicycle chain that is off track... just rattling around. it's hard to describe it any better than that. It gets louder if I give it more gas.
To me, it doesn't really sound like an exhaust rattle... more like a really loose metal belt or something that rattling and scraping as it rotates-- of course there are none, and I've replaced all the belts anyway.
It seems to come from the front end of the car.
Hope that helps... it's hard to describe and difficult to get a sound clip of, since it only happens while driving.

 

the sound seems to have two parts.. a scraping noise and a clicking noise... the click follows the scrape. Of course it's happening really fast so it sounds almost continuous.

 

I finally took it in to a mechanic, and he said that the noise is valve clatter... he said that my camshaft may be worn, or my timing is advanced too far, or my valves need adjusting, or my distributor timing needs adjusting.

So... what's the best thing to try first? I think before anything else I will try a higher octane fuel, but even if that works I don't want to have to pay $.30 more per gallon...

Also, does anyone have experience adjusting valves? Do I need special tools?