Video of rattle noise at idle
 

I'm hoping someone can help me out. This is a video or my car idling (sp) with a weird rattle noise. I don't know if it is just a valve or something else. But after my 3.0 incident all rattles scare me and I'd really like some help.

Motor is a 85 3.2 recent transplant into my 76.
Oil level in the car is well over medium but not quite to full.
DME is a good one I borrowed from a fellow pelican and swapped in but I don't know what year it was from.
RPM's for this video are between 950-1000 RPM.

Thanks

http://www.youtube.com/watch?v=z8q66jt0YZ0

Spooky!:eek:

It sends shivers down my back.

Does it smooth out at higher revs? If so , my guess would be a bad cam timing chain tensioner.

Sounds like really bad detonation, like maybe the car has been sitting for a year and is trying to ingest bad gas with clogged injectors. Can you give us some background, including any recent work done?

Motor was from a wrecked car. I'm not sure how long it sat before I got it. I purchased it at the end of Nov. I got it in my car in Dec. I tried starting it then, but it sounded like crap so I cut it off. (which I think was the flywheel hitting the speed sensor) I moved, the car and motor sat until March. In March I started working on things. Put in the 3.2 fuel pump, 3.2 fuel filter, new speed and reference sensors. My DME didn't seem to be working right so I swapped it for a working one, which is the one that is in the video. It has a little over 1/2 a tank of 93 octane in it, fresh as of Sun afternoon. I swapped my DME back in with the new gas, the car ran like crap. When I put the timing light on it with my DME the timing was way off like 1" advanced. I didn't test the timing with the working DME.

What other info would be helpful?

Have you tried removing the fan belt for a second and listening?

That's a good idea. It could eliminate the fan/alternator out of the equation.

Someone else suggested that but I haven't done so. I am traveling at the moment but as soon as I get home I will check it.

Sure it's not the cat heat shield?

Get a 12" piece of garden hose, one end to your ear... see if you can find where it's coming from.

Double post... wonder why the new Pelican software keeps doing that.

I think the secondary lower pitched sound, like a groaning noise, is the fan rattling back and forth on the alternator shaft, but the louder and higher sound seems more like detonation. I kinda think the ignition timing is off, at least that's my best guess.

Check all the rocker clearances. You may find a rocker nut has come loose.

Can you move your ear close and get an idea of exactly where the noise is coming from? Fan/chain area, valve cover left or right, etc.

No cat sheild. No cat's. B&B header copies into a flowmaster.

I can't tell exactly where it is coming from. It sounds like the alternator and the driver side upper valve cover. It doesn't sound like the chain.

I agree with rusnak. It sounds like an old 11:1 compression muscle car dieseling along on pump gas on a hot day after the ignition got turned off. Not sure how a DME would get the timing off by that much ...

Mucky distributor...

ianc

If your car has a catalytic converter, check it and make sure it's not falling apart inside.

EDIT: Nevermind, just noticed you don't have a cat.

Dumb question but do you have 2 of the plug wires switched perchance?

Not so dumb....

I'll say that would do what you hear.

I've checked and rechecked and checked the wires again, I was hoping it would be something simple, but I'm not that lucky.

I did get an email from the guy I bought the motor from, he said they replaced the chain tensioners but that one of them failed. He said it was replaced and that the other one seemed to be good when they installed it. He did mention that there was a batch of bad tensioners out at that time. I'm guessing the rattle could be coming from the chain if that is the case. He also suggested that since my timing is off that the cam may be timed incorrectly.

I'll be home tomorrow morning and plan on checking a few things, plug wires again, taking the fan belt off and letting it run to see if it is the alternator, and anything else I need to check. Thanks guys.

Sure doesn't sound consistent enough to be a failed tensioner or loose valve. Check my post in the engine forum "Rod knock?" or something like that. I had video with a very consistent mechanical noise. You could see it in time with a timing light. This seems much different. My first guess would be your fan is slapping around on the housing. Inspect that first. If you don't see anything obvious, while you are in there, you can run the engine for a few seconds (just a few seconds) with the fan disconnected to see if the sound is still there.

Are you running old nasty gas? It doesn't sound like spark knock but you never know.