98 Wrangler rattles on start?

Question

It definitely sounds like an exhaust problem, but I can;t tell what or where it is. It does it every time I start it up and after about 30+ seconds in idle, it'll cure itself but when I take off in first gear, it comes back again. Usually 3rd, 4th, and 5th shift just fine and there's no rattle it's just 1st and 2nd that rattle and after it's been running for about 5 minutes, it'll finally sound normal.

A couple months ago we sent it to the shop to get a crack in the exhaust fixed because the exhaust was shooting straight from the headers and it was loud and annoying. That leads me to believe that the shaking exhaust may be what caused the crack in the headers and made me fix it, but again, I have no idea where to look or what to do for this fix. I hear rattling in Jeeps is quite common in years like mine because of poor design.

Answer 1

Hi,

You might need new motor mounts it is leaning to much..

Brake torque it(give it some gas while you hold the brake with your other foot) and see if the motor mounts are bad. The motor will lift up and come back down when you let off the gas. Be careful brake torqing it, if you don't feel confident let someone else who has done it before do it.

When you brake torque you will probably get the rattle.

Have someone listen outside for the rattle to get a location also.

After you shut it off look at the exaust pipes and see if you can see where it is hitting.

Also check that the exaust was hung right in the first place, also look for broken or missing clamps and hangers. Check any heat shields for being loose.

Answer 2

My 98 Wrangler did the same thing, it turned out to be the catalytic converter. I got a recall letter in the mail regarding this and the dealer replaced it at no charge and then the rattle was gone. Check and see if you can get it replaced under the recall. I am in CA and they wouldn't let me get the smog check done until I had it replaced.

Answer 3

I easily have an identical jeep so i'm kinda leaning in direction of what Jim pronounced in spite of the fact that i understand its a timing chain and that is uncommon for it to bypass.... yet Jim replaced into top whilst he asked with reference to the mileage ?

Answer 4

try a higher octane gas

Answer 5

sounds like ur cat converter. if its not that your resonator might be blown.