Rattle at Idle comes and goes

[Kuda]

I have a 94 mtx body has 139k motor installed in feb with 69k on it. I have a rattle that comes and goes at idle, the rattle lasts a few seconds then goes away then comes back a few seconds later. checked codes no codes come up.. It sounds like its coming from the passenger side. Car has been taken to a few shops nobody can for sure figure out where its coming from. one mechanic suspects a pulley. there is no wiggle in any of the pulleys. Has anyone had this problem before?
Any ideas at what it can be is appreciated

 

[Black '93]

Could be your cat rattling, if it is starting to fall apart on the inside, or it could be the exterior of the cat like the heat shield starting to come loose. One of the bearings from a pulley could be going bad and starting to make noise too. You should take off the belts and check all of the pulleys and spin them just to make sure they are good. Could also be the shield thing that covers the exhaust manifold coming loose or I suppose even the engine torque damper rattling cause it's a bit loose (the shock looking thing mounted to the motor from the strut tower on pass. side towards the back). What kind of a ratlle is it? Does it sound very tinny? does it vibrate the car at all?

 

[Kuda]

No cats on the car, the rattle is a fast metal on metal sound, Like something is loose. I listened with a long screw driver but it was no help at all. To me sounds like its coming from inside the motor. it will rattle for a few seconds then totaly disappear then come back in a few seconds, it does this over and over again at idle, you can not hear it when you are driving the car. It does not make the car vibrate. I am going to take the belts off and check the pulleys tomorrow.

 

[Black '93]

find anyting out yet? If it sounds like it's from inside the motor, that's not good. I had a wrist pin on my MTX making a similar noise and it only happened at idle and it would come and go. Then it came back and blew up my F%ckin' motor. Don't beat on it and keep RPMs low as **** if you have to drive it...

 

[TYSHO]

find anyting out yet? If it sounds like it's from inside the motor, that's not good. I had a wrist pin on my MTX making a similar noise and it only happened at idle and it would come and go. Then it came back and blew up my F%ckin' motor. Don't beat on it and keep RPMs low as **** if you have to drive it...

Wow, that sucks!


On a side note, maybe check the o2 sensors. I had mine work loose and have some rattle. However, mine gave me a code for the problem, as it got worse and just ruined the sensor before I caught it.

Besides that, maybe it's something inside the transmission bell housing? Clutch chatter, TOB, PP strap...

Good luck on your find and hope that it's not the worst [wrist pin].

 

[Kuda]

A friend of my sons is going to do the rod bearings in his shop next friday.. he is also going to try to pin point where the rattle is and fix it.. took the belts off the other day and they seemed fine.
Would the timing belt make the same kind of rattle? or would it be more steady and not come and go?

 

[SHOZ123]

Had an alternator bearing go bad on my '97 and you would of sworn it was a rod bearing.

If the noise is gone when the belt is off it's one of the belt driven accessories.

 

[SHO_24_yamaha]

mine has that problem and when I push in the clutch the nosie goes away so i guess mine is just a clutch chatter

 

[Ishodu]

Remove the hermonic ballancer and timing covers and check for crank cancer! There is an article on www.shotimes.com

 

[Kuda]

They had no room in the shop to do any work on the car, Whip from the forum when he has time is going to come up and do the bearings.. is there anyway to findout if its a wristpin. remove the sparkplug wires 1 by 1 and listen for the rattle? I have been able to sort of pin point the rattle. passenger side and it seems to be loudest on the edge of the valve cover. 12 yrs i have had a sho and i have spent 2000 so far this yr with replacing motor.. if its a wristpin i am ready to pack it in and move on. 2 kids in college is where my money has to go for 1 more yr.