3100RPM rattle, not pinging

2

2000GTNY

New Member
Jun 21, 2005
31
0
0
Albany, NY
#1
I get a rattle, consistently at 3100 RPMs. Its definitely not pinging. Its certainly as if something is loose. It is just so odd that it only occurs at precisely this RPM. I can hold the RPM and keep the rattle. There is absolutely no power lose or change in the motor so I don't think it's internal. It doesn't even sound internal. Its like a brake shield type noise or a stone in the heat shield type rattle. Its just so baffling that its exactly 3100 every time, in every gear.

Thanks for any input!

Edit: The rattle goes away above 3100. Its a quick thing as the car accelerates. I wasn't clear in the first post about that.
 
#4
The heat shields themselves are not loose. If indeed a rock is inside the shield area, how do you open the shield to get it out? Can the shield be removed permanently? I know I took it off on my Ford Ranger, but the converter was a mile and a half from the body on that truck compared to a Mustang!
 
#5
Must have missed this one. I'm no mechanical expert, but search for my threads and you'll see I've been going thru this for awhile. Mine makes a rattle, between 2.5k and 3.5k roughly, then goes away. Warm or cold, in gear or neutral. Ford thought it was a busted cat, until I took the cats off with an O/R mid-pipe. I checked the dust shields and everything else. Its very strange cuz its hard to locate where the sound was coming from.

Finally...Ford figures out its a worn valve guide per the TSB. Putting 2 brand new heads on as we speak. I'll make a post about the results. Hope that's not your issue.
 
#6
I really hope that isn't my issue! I can say that I don't have a range like you have for the rattle though. Its quite exact, and it really sounds like a loose shield. I just can't find it. I got under the car and checked the heat shield and they are tight as can be with no rust. Naturally I couldn't see any rocks but who knows. The brake shields look fine too. It so wierd that the vibration resonates to the 3100 rpm so well! If I am hitting the gas hard, there will be a really short "bzz" at 3100. If I go up a hill and hold it at 3100, I can keep the "bzzzzzzz" going.

Its very irritating!

Did yours give you any power loss or any signs that the heads were involved? My engine pulls hard, I get great gas mileage, and in fact the car is perfect besides this stupid rattle.

Thanks for the help.
 
#7
Well mine doesn't rattle throughout that entire range....it only rattles for about 200rpm's. But can happen anywhere within that range. From what I've discovered, it rattles at higher rpm's when its colder, and lower when its warmer. On mine, I can sit in neutral and hold it at about 2.5k and it will rattle all day long. Didn't notice a power loss or anything, but then again its been doing this since I bought it used so who knows. Don't feel a power loss when it starts rattling though. Mine really sounds like a piece of metal shaking around inside a metal coffee can. It doesn't really sound like its coming from a head either. It actually sounds like its coming from underneath the engine somewhere.

Do a search for "valve guide". I think I found the entire TSB for this problem with some diagnostic info. BUT....I don't have my car yet....my rattle may not even be the heads....I'm just going on what the shop foreman has told me. I'll know early next week. If it still rattles, someone's dying!

Here it is...
http://forums.stangnet.com/showthread.php?t=519271&highlight=valve+guide+tsb
 
#11
Next weekend I'm going to get my car up and check those shields out very well. It REALLY sounds like something caught in there. It is just so wierd that it resonates perfectly at 3100 everytime.

Let me know how the heads turn out! Good luck!
 
#14
I had the exact same problem, mine did it consistantly at 2800 rpms though. After hours upon hours of searching, it was the front brake rotor backing plate/shroud... Dont know why it only makes noise at that rpm, but it would be worth checking...
 
#15
well after searching this forum for rattles and noises i finally found this one that relates to mine. it's in 3000-4000 rpm rangs and it is a metal on metal rattle. it happens everyday when i start the car until i turn it off and i can't figure it out either. i've checked everything on the underside of the car and nothing is loose but the sound is coming from under the car. i don't know what to do.
 
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