mustang_marine8762

So I got this sound comming from what sounds like the exhaust and it's driving me nuts. It's not really a rattling sound but kinda like a light knocking sound. When the windows are down it's sounds like it might be comming from somewhere around the cats, but when the windows are up it sounds like it's comming from the back of the motor through the firewall. I doesn't sound like anything serious, but it's enough to make me nuts. I hope someone knows what I'm talking about and can help. I can't really give you more than that. You just have to hear it I guess.

wills98cobra

It may be ur cats. I would look uder the car and see if you can see anything or take it 2 a exhaust shop and have them check it out. And see what they say.

Dan04COBRA

Could be anything from a piston knocking to an exhaust leak. The only option is to get it up on a lift and check for leaks.

Maybe you can use some mechanics ears or a large screw driver while the engine is running and see if you can locate the noise.

mustang_marine8762

Yea...I thought it might be a leak as well, but not to sure. What would I have to do about a piston knock? Would that be a sign that it's time for new aftermarket pistons?? [sm=groupwave.gif]

TruckStang

From first hand knowledge, I had that same knock when I bought my car and figured it haad something to do with the cats. it ended up being a knock in the motor where the main bearing had slipped/blown and created a whole mess of trouble. Does it get louder when you step on the gas? If it does, its time for a rebuild. Hate to say it, but it was a pain. I would get a wooden hammer or a long screw driver and set the end on the valve covers at the area of each piston, just listen for a knock and it will be noticeable if it is the piston. If that's the case, you should get it to a shop if you don't have the know how to rebuild. I hope for you that I am wrong and it is something wrong with the cats. Good luck.

mustang_marine8762

If it is the piston and I need the rebuild, what kind of price will I be looking at for that? And what does the rebuild consist of? Rods and pistons??

TruckStang

rods, pistons, rings, bearings, possibly boring(sp?) out the cylindar wall if it is etched really bad, otherwise a hone job, umm...crank should be fine...but you will have to get the metal shavings out of the entire block, you'll need to replace the seals just to make sure everything is in a like new condition. There might be more but I can't think of it at the moment. Prices will vary depending on how bad the damage is. Umm...I would check some speed shops andcheck their prices and look online at rebuild kits. I hope this has been more than enough information and I will try to post some more if I remember anything that I left out.

Js 99 GT

Is it louder when you first start it? does the knock rev with the motor or stay constant? Does it fade after the motor warms up?

mylongvictor

Pepto Bismal......... lol...... Ehhh Its a Ford.... Parts fall and get lose all over the place. My car rattles..... the break "clicks" everytime I engage it.... The clutch doesn't full engage unless its stomped all the way to the floor, and the tranny gives me a hard time with Reverse unless I "play" with her.

mustang_marine8762

You know...I don't think it's the pistons though. It's not a loud knocking sound. I can't really describe it. I know what a knock sounds like, and this is not it. I'm gonna check the cats and see what's going on down there. Doesn't a knock usually make a loud noticable sound?? I'm gonna check it out and get back with you guys with what I find?