http://vid244.photobucket.com/albums...7/MVI_4853.mp4

Not sure if this link will work to this video. Does anyone know what the rattling noise is when accelerating the engine? I thought it was a manifold gasket leak at first, but in looking at it closer, possibly not.

 

I can't see the video but rattling under load is usually detonation, so check timing at the distributor with the spout plug removed to disable computer advance, you should see 10deg advance as the base setting. If it's higher than that loosen the distributor and turn it until you get it right and then put the spout plug back in and make note of how much more advance the computer adds.
If the base timing is set right then pull all the plugs and examine the color of the electrode, you should see a tan brown. If they are all white the engine is running lean so you have a bad O2 sensor or another major issue, pull codes and report back. If only 1 plug is white that cylinder is running lean, that could be a dirty injector or it could indicate a gasket leak on the intake or exhaust for that cylinder. Run some seafoam through the motor or have the injectors professionally cleaned.

 

Would need to hear more, engine at idle in park engine at idle in gear etc but based on what could hear almost sounds like a busted flex plate. (assuming you have a auto trans of course)

Starter remaining engaged with flywheel?

Or an accessory driven by the belt about to blow!

Just not enough video to begin to pin point what it might be or where its from.

Listening to it again I think..yea maybe... my first best guess based on the video would have to be the starter.

At the point when you first throttle it up increasing rpms tends to sound just like a starter hit when engine is already running one that matted with the ring gear teeth spun with it.

 

Remove your accessory belt and make a new video. The fan and stuff makes too much noise. If the sound goes away, could be air pump.
The noise doesn't really sound like a broken piston or wrist pin, kinda does sound like torque converter nuts are loose (never had cracked flexplate bad enough to make noise)

It's not detonation because it was just revved while in park and goes away a little with more rpm.
Check and make sure starter is tight and not loose to hit ring gear.

 

I'll take the belt off tomorrow and will make another video. I replaced the starter about a year ago. It has been making this noise for a long time. I am fairly sure it made the noise before and after I replaced the starter. I will check the bolts though. It does have an automatic transmission. From in the cab, it is quiet at idle and when accelerating, it sounds like an manifold leak, but fairly sure it is not now.

 

http://vid244.photobucket.com/albums...7/MVI_4855.mp4

Here is the sound without the belt. It still sounds about the same. The noise is coming from the right side, low by the exhaust manifold. I believe it must be an exhaust manifold leak towards the firewall. I'll look closer next time I do a cold start.

 

Awesome. Much better video without the fan noise and air pump.

That is an exhaust leak for sure.
Could be manifold gasket, but could be the collector flange rotted, or manifold nut, and flange loosened up causing the leak.
Either way, I think we got it figured out.

 

Thanks. I believe it is for sure an exhaust leak. I looked closer last night, through the wheel well. I can see where one of the manifold bolts is broken off, so a previous owner must have attempted to removed it. Also, the EGR metal tube is welded. I may just take it in to have it worked on as the old studs (some of them) will need to be drilled out. Not much room to get at it.