Bob,post some info on your build such as IRS , 3 link,EFI or whatever might be relevant.
Based on you sig line I have no idea on how to help with your noise problem.
Paul

 

Paul,

Sorry 'bout that. Got a mild build 302 with Edelbrock heads and intake. 24# injectors, 70MM TB, Pro-M, full roller. 9.0 CR . Tranny is a T5, 3-link in back, 3.55 gears.

The noise doesn't sound like it's coming from the motor, but who knows?

Bob

 

Bob,the rattling sound often times is caused by too much timing advance.
Where do you have it now?
A good place to start is 10 degrees and work up until the engine pings under load and back off a little at at time until it's gone.
just a thought.
Paul

 

Hearing it over bumps?
Do you have cats?
if so tap them with a rubber malet and listen for rattle, it is posible the cats have gone bad.
Just a thought. I know its a guess without actually hearing the noise.

 

Yeah, I hear noise going over bumps. Both noises sound metallic, so it's possible they're connected. I don't have cats, so we can eliminate that. As stated earlier, the timings been checked. I don't know what's it's called, but I unplugged the wire by the distributor and the timing was spot on. I didn't check it after re plugging it though. Are there marks there for checking if the advance is right?

Sorry I don't know this stuff. My experience is mostly motorcycle related, and they had mechanical advance with idle and advance marks so you could tell if the advance was working also.

Again, thanks,

Bob

 

Check the sidepipes for loose internal baffles.

Bill

 

Good call Bill, I'll check that when I get home. I got the Gas N Performance pipes, so I'll be surprised if it's something they did like leave something not tight. Their quality is amazing and both of those guys are pros. I'll let you know what I find.

Bob

 

Nope, that's not it. I got on my hands and knees and "thumped" them with the heel of my hand and not a rattle in either one. Good thinking though. On the way home I was thinking you had it.

Bob

 

Check the trunk latch, make sure it holds the trunk lid from bouncing around. I split a piece of small hose and slipped it over the pin.

 

Thanks, Rich, but not that either.

 

Check your e-brake cable bracket at the rear of the tranny tunnel. It often needs to be ground off slightly, or the driveshaft u-joint can hit it. It may be that the rear squats under torque, or going over a bump, the joint comes into contact with it. Look for marks on joint, and bracket. Just a thought.

 

Bob, Cannonball Cobra is correct in his assumption. If you get a boost in power the same time it starts pinging, 3500 rpm, the timing is definitley advanced too far. You are getting pre-ignition. Make sure that your temperature is correct so you are not getting too high of a temperature in the heads and combustion chambers. ( another reason for pre-ignition )
Then, even though the timing may be right on, you need to fix the rattle.
First mark the distrubutor, draw a line down the distrubutor shaft with a sharpie onto the block, so you know where you started and can return to this point if need be. Loosen the distributor hold down bolt and turn the distributor the same way the rotor turns, about 1/8th inch at a time until the pinging stops. Testing under load after each movement of the distributor. This retards the timing. You may feel a small drop in power, but it is better than a hole in a piston, ( worse case senario ). Now see what the timing reads. Do you have degree tape on your damper? I don't know how much you know about timing an engine so I hope I don't sound too simple in my explanation. Good luck. Gregg

 

Gregg W,

I will do as you suggest, give that a try as it's very late tonight. Timing was the first thing I thought of. I don't know how timing is advanced with my car but possibly it's advancing too much? I will try that tomorrow. Thank you very much.

Bob

I will respond after I try

This reminds me of a saying from my motorcycle days, "The thing was running really, really good just before it blew up!!" And , my car hauls ass!! I'll get back to you Gregg.

 

It's unlikely that the computer is advancing the timing too much, it would be that your base timing is too advanced. I think 10* BTDC is standard from the factory. The noise that you are describing is classic for detonation and if you are noticing it every time there is a heavy load on the engine, that would be consistent with detonation as well. In my mustang I can make it ping if I lug it up hill in low rpm in a high gear but if I keep the revs up and drop a gear it goes away.
Another possibility is you are too lean - had that happen my mustang as well. That's going to involve a trip to the dyno to figure that out and that can result in a swift emptying of your wallet. I think just to put it on a dyno with a wide band should only cost between $50 and $100 but it might be worth it. It's what the dyno tuner does after that, that can get expensive!

 

Hi Bob,
Could the noise be the driveshaft binding under hard accelleration?

 

Check all your quick jack spacers to see if one might be loose. One of mine was (right rear) and it made a very annoying rattle at idle. It sounded like it was coming from the passenger side pipe or front wheel well which is far from the source and only happened at the right frequency of the pipes. Another noise I get sometimes over bumps is the passenger side belt sliders in the trunk rattling around when no ones using them.

Cheers, Rod

 

Bob,

Do you have welded bungs for air/fuel probes? If so check the plugs to be sure they are secure. Drove me crazy for a few days.

 

One other easy check , is to hit the side of the car, under the fender vents, or the passenger door, with the palm of your hand....You may find that the vent attachment is rattling, or even the internal brace , in the door.

 

If it happens under acceleration and big bumps could you have the engine/trans etc hitting on something when under torque load etc.??

It might be worth a look at the tight areas underbody area for signs of contact....and that engine mounts etc are properly torqued.

Jeff

 

One possibility is the aluminum panels may not be rivited tight enough or not enought sealant between the panels and the frame. At just the right engine frequency, the panels will vibrate just enough to give off the metal to metal sound. Happend to me and after adding a few more rivets problem fixed.

 

Bob, check to make sure your sidepipe hangers are not hitting the frame.
I recently had a similar rattle and found the passenger-side hanger was tight up against the frame. Engine vibration at certain rpms caused a rattle that sounded just like those nuts and bolts in a can you're hearing. The driver-side hanger had an inch or so of clearance with the frame, so I loosened the motor mounts and evened things out and now, no rattle.

Good Luck,

K.G.

 

Check to make sure the sidepipes are not breaking at the weld. When hitting bumps they flex and can sound tinny. Also under accleration the flex between the motor and the frame make them rattel. Look for exhaust staining around where th pipe meets the rear bracket

 

I had a similar problem and found that the pinion angle shifted and the drive shaft was hitting the frame. Jack up the car at look for marks as mentioned above. Of course if you hear the noise when the car not moving ignore this post

 

Good Morning guys, it's Wednesday AM and I'm just getting back to this thread. Lots of replies and things to check but have been busy, yesterday was just a blur. Today looks to be same and don't know when I'll get to look at my car, but I will and I will let you know what I find. Once again, I'm amazed how great this forum is.

Thanks, Bob

 

Man, I've been busier than hell! Got my car tore apart with the rear axles out of it putting Wilwood brakes on it that I got from Gordon. While having it up in the air, found that my panhard bar was loose and would rattle if I shook it.

I'm waiting on new e-brake cables (another story) and should have it back on the road by next tuesday. I had retarded the timing an 1/8" last week to eliminate that possibilty and the noise didn't change. The loose panhard bar could possibly cause both the harmonic rattle and the rattle going over bumps. I'll let you know when I get to drive again. I know many of you were helping and appreciate the interest.

Bob