When I start my 1991 Jeep Cherokee there is a very loud rattle (can tell if it is the engine or the exhaust system). It quiets down after the Jeep warms up after driving a while. Never really goes away but gets quieter by 20 to 30% after the Jeep warms up.

I have read about bad motor mounts etc. Not sure what could be the cause of this loud noise. Its a 4.0 L.
It drives fine, has power, just loud. No holes in the pipes or muffler.
Any ideas to point me in the right direction are appreciated.
Thanks

 

If it goes away with temperature, then the only thing that makes sense to me is some kind of internal motor part that isn't getting enough oil at startup. Oil is thick when it's cold and gets thinner as it warms up.

You might have a lifter tick.

 

mine i think is piston slap. you can search, read all about it

 

Hmm well I guess the most obvious is thing would to be to make sure the exhaust isn't coming in contact with the crossmember. I'm not sure how temperature comes into play. But you need to rule it out. It can cause some funky noise.

 

Yes, look here and at the engine mounts.

What brand of oil filter are you using?

Ever shined a light in your oil filler hole to assess sludge build up?

Could also be loose flesplate bolts.

Time for noggin pokin.