Solution for odd rattle at idle

[anthrax323]

Pardon my ignorance, but would you guys mind elaborating a bit more on the rattle/symptoms this causes? My 2001 XJ has a rattle that seems to originate from somewhere very near the firewall, somewhat toward the passenger side of the vehicle. Everything I've read points to it being related to an A/C component mounted on the firewall (a canister of some sort, can't recall the exact name) but since I'll be working on the car tonight, I might as well pull off the inspection cover and check it out...

FWIW, my rattle is not audible outside the vehicle or inside the engine compartment (haven't used a stethoscope yet though).

 

[kastein]

On the pass side it's probably the evac purge solenoid, part of the emissions control system. If you can hear it everywhere, especially when you goose the throttle, it's probably the torque converter bolts. Easy to do, it took me 30 minutes on my stock MJ with no lift. Most of that was spent trying to get the blasted inspection cover off, Chrysler used the same length bolt on both sides. On one side it would interfere with the downpipe if they put it through the logical direction, so they simply put it in the other way, which traps it behind the downpipe completely. I sawzalled the head off and replaced it with a proper length bolt going the other way. It's a metric head bolt and some high property class hardened material but it's just holding a piece of 1/16" aluminum down so replace it with whatever you have in the spare bolt bucket.

 

[anthrax323]

Thanks for the info kastein - to clarify, when you say "everywhere", do you mean outside the vehicle as well? If so, I may be able to rule this out.

To further clarify the noise I'm hearing, it sounds like more of a knock than a metallic rattle, and at a decent rate... Probably ~600 taps/knocks per minute, slightly erratic in their rhythm. Doesn't happen all the time, and goes away once the car is moving.

I'll be under the Jeep all afternoon anyway, so screw it - I'll pull the cover and chock it up to responsible maintenance/inspection. Thanks for the heads-up on those bolts - I'll get my back-up car's battery on the charger in case I need to go to the parts store

 

[kastein]

Yeah, you probably will hear it with the hood up at the very least. Mine was bad enough that a friend of mine responded by taking a step back and yelling "oh my GOD" the first time he heard it. It sounded an awful lot like I was missing a rod bearing or two, but I obviously wasn't because I still had oil pressure.

 

[Talyn]

The evap purge solenoid isn't that audible with the hood up and in the engine compartment. The reason is that the isolation mount doesn't do a great job of isolating and uses the firewall to amplify the sound. Try bending th ebracket a bit different and see if that helps. You can put your hand on it and feel it though.

However, that is more of a ticking noise than a rattle.

 

[itbrokeagain]

When I had my Yj they would back out all the time. In fact I actually broke 3 flexplates. The sound that makes is not something I think I will forget.

 

[jaydubya2003]

The "rattle" I had was very metallic, almost sounded like a bottom end engine noise (like a bad bearing, or knocking rod) and would make a "ping" sound every time it felt like it "hit" whatever it was hitting. It would only happen at idle, or when making a turn. It wouldn't make this noise when driving down the road, but at freeway speed I did have more vibs coming through than now after it's all tightened up (makes sense why)...lol

 

[robsjeepxj]

I was just recently told that the reason those bolts come loose is because they have actually stretched and once they do they should be replaced or even though the bolt are tight the flexplate can still become loose again. I had those same bolts loosen up on mine about a year ago and was surprised too to find them loose and was also happy when tightened the bolts up made the noise go away but now it's back and only this time the bolts are all tight. I just heard this yesterday from local jeep mechanic friend and am going to be picking up the bolts from the dealer today so I'll let you know how it turns out.

 

[kastein]

If it makes the noise for too long it actually stretches the holes in the flexplate, not sure about the bolts themselves. I cranked the shit out of mine and called it good and it's been quiet since then, didn't even use loctite. I knew I had a tranny swap coming up in the future so I saw no real reason to do anything special so long as the noise went away.

 

[camshaft2389]

so I had that rattle noise on my 89....and sure as shit I took the plate cover off and the bolts were loose...so I loctited em down and my noise went away....but come to find out my alternator made that same noise 1 week later!! and it broke my belt after squealing really bad...so check ur alternator for that rattling noise also

 

[XGarfX]

Where is this inspection plate at? Mayb mines just so covered in grease and oil that I can't even see it!

 

[kastein]

it's the bottom driver side section of the plate covering the front of the bellhousing, something like 3 bolts hold it on. A few small ones and one really honking big one.

 

[aldous]

So I got the plate off. Turns out 15mm is one of the sockets not provided in my cheapy set. Would a 16 round those bolts off at 25 pounds? Seems like it might be okay. 25's not that much and it's catching pretty good. Supposed I could go borrow one or go buy another set. Would rather just finish though.

 

[aldous]

On second look, I don't even see how I would get the torque wrench in there behind the exhaust.

I have a 15mm box end, thinking about taking them out, loctiting them, and going with the "tight as XXXX" with the box end method described earlier...

 

[kastein]

I'd probably just crank em down honestly. I did that on mine (think I said that on page 2) and it lasted another 20k miles without a single sound (would have been longer but I swapped the motor due to broken mounts and converted to 5 speed, no more flexplate), I didn't even wipe the oil off them or put loctite or anything on, just cranked the crap out of them. I'm pretty sure people overthink this one.

The bolts go into about a 1" square 3/8" thick tapped steel boss on the torque converter, I would bet you could break the bolt head off before you actually strip the threads. As long as you use your hands only and just a box wrench I don't think you will have to worry about breaking or stripping them.

 

[Talyn]

You can fit a torque wrench in there. You just have to position the bolt just past the engine block on the driver's side near the exhaust. As for the 15mm socket, see if a standard socket will fit. I wouldn't use a 16mm.

 

[aldous]

Hey yeah I decided to go 15mm box end. I was actually having the opposite problem I thought I would where the shaft just started spinning around too early. Ended up just putting a flathead in one of the teeth against the left side of the inspection port, worked pretty good. Thanks for the ideas.

 

[Talyn]

You did it the right way.

 

[santaxj]

I know this is an old thread, but I tightened the bolts on the trail and it was noise free for about 9 months. This morning I looked again and 3 were loose and the noise was intermittent. This morning I removed the 3 loose bolts cleaned then put loctite on the threads, retightened. Hopefully this is the last time.