RATTLING ON ACCELERATION

[Mugz]

I have a 96 roadmaster with an LT1. I bought it last month. It was sitting for about 5 months or so, before I bought it.

Problem:

When I accelerate it rattles like hell from up front (sounds like a bunch of wire clothes hangers rattling inside of a pipe). I've been told that it may be that the gas was bad. I put in 93 octane and some gas treatment and some fuel injection cleaner. Drove about 150 miles but its still doing it.

Any suggestions.

[03slowZ06]

Rockers might need to be adjusted. Can you narrow it down as to where it is comeing from.

[96redlt1ta]

Is shaking though the drivetrain?

[AdioSS]

does it happen only when driving? is it coming from the engine? More info would help.

[mrcadillac]

I have a 96 roadmaster with an LT1. I bought it last month. It was sitting for about 5 months or so, before I bought it.

Problem:

When I accelerate it rattles like hell from up front (sounds like a bunch of wire clothes hangers rattling inside of a pipe). I've been told that it may be that the gas was bad. I put in 93 octane and some gas treatment and some fuel injection cleaner. Drove about 150 miles but its still doing it.

Any suggestions.

My Buick was doing this when one of the exhaust mounts was hitting the pipe, and again when one of the pipes came loose. The rockers should't make THAT much noise if they are loose.

[RokGoblin]

does it happen only when driving? is it coming from the engine? More info would help.
I have the same problem with my 96 Caprice 9C1 w/LT1...metal coat hangers rattling on a pipe is a pretty darn good way of explaining the sound.

This started a few months ago and seemed to come from inside my dashboard so I removed the dash pad (and cracked it yikes) to see if I could figure out what was rattling. I found nothing to my dismay. I think it is coming from the engine compartment, but I have not been able to figure it out yet.

The rattling increases as I accelerate and disappears if I let off the accelerator. SO lifters might be the answer, but I am not really a mechanic. I can turn wrenches and figure stuff out if I have schematics and wiring diagrams and those precious service manuals, but adjusting valves, etc. is not something I have attempted before.

So are the rockers, lifters, or valves the most likely cause considering my explanation above?

[bubbleboy301]

cheack th turqe converter bolts probley lose

[The Fooser Guy]

Can you get it to make this noise while it's sitting still (with the hood open and slowly opening the throttle by hand)? It will be a lot easier to diagnose where the noise is coming from that way.

If you can get it to make this noise; take a 'stick' (wooden dowl, yard stick, etc.) and put one end of it 'in' the first knuckle of your thumb, then close the rest of your fingers around the stick Put your thumb-knuckle 'in' your ear and (carefully) probe varios parts of the engine with the other end of the 'stick'. You will be able to listen to different parts of your motor (water pump, alternator, exhaust, fuel injectors, etc) as you move the stick around. Now listen for this 'noise' and see if you can isolate it - then let us know what you find out.

HTH.

[RokGoblin]

Can you get it to make this noise while it's sitting still (with the hood open and slowly opening the throttle by hand)? It will be a lot easier to diagnose where the noise is coming from that way.

If you can get it to make this noise; take a 'stick' (wooden dowl, yard stick, etc.) and put one end of it 'in' the first knuckle of your thumb, then close the rest of your fingers around the stick Put your thumb-knuckle 'in' your ear and (carefully) probe varios parts of the engine with the other end of the 'stick'. You will be able to listen to different parts of your motor (water pump, alternator, exhaust, fuel injectors, etc) as you move the stick around. Now listen for this 'noise' and see if you can isolate it - then let us know what you find out.

HTH.
Cool!!! Will do, but prolly gonna be next weekend or after. Thanks for the advice.

[mrcadillac]

Lashing the valves is very easy. Take the valve covers off, start the car up(Make sure you put the brake booster hole back on). Loosen the rocker till it clacks, then tighten till is just stops. Then do your preload. I think stock is a full turn. I normally do mine to about 1/4-1/2 turn. But I don't think this is the issue here.

Rattling heat shield? Have you actually gotten under the car, and looked at the exhaust? That would be the first place to start. The heat sheilds ended up rusting off my Red Roadmaster. They were making a little rattle, so I just grabbed with with a good pair of gloves, and yanked them off.

[94smasher]

could it be the insides of the catalytic converter coming loose? My 95 Suburban was making that kind of noise, and that's what it turned out to be. and now my 94 Roadmaster has been doing it for a while...

[RokGoblin]

I have not yet alloted the time to investigate this. I am not sure it is really valves but the exhaust heat sheilds seem to be closer to explaining the sound. This is the factory exhaust with just under 200K on it and it was a service duty 9C1 Caprice. I am sure there are lots of heat stressed parts under there I need to check out.

On the topic of the cats, I am getting P0420 and P0430 Catalyst System Efficiency Below Threshold codes that repeatedly come back, so I perhaps the cats are rattling as previously mentioned. I do have an exhaust leak that I need to track down as well.

Thanks again to everyone for all the recommendations and I will try to get my butt under that car soon and investigate.

[mrcadillac]

The 96's are a bit picky on certain items. Like if a cat stops working right. The 2nd set of O2 sensors keep an eye on each cat, and make sure they are working right. I forgot to see what codes my 96 Caprice is throwing. I cut the cats off, put straight pipes in there, and never did anything with the PCM. It runs fine. I have a 95 PCM for it, that has the OBD-I conversion done on it. I just need to load in a stock Program. Right now it has a tune for a full bolt-ons motor, with a bigger cam shaft. That might not be optimal. :D