[hart4jeeps]

I'm back for advice. I tried to address the prob which is a tapping noise in cold 4.0 (2006 X with 75000 miles) that vanishes when engine warm. I went 5w30 (forgot synthetic type -will do next time) with seafoam with change along with good filter. Also added tank of premium with 1/2 bottle seafoam.

No change. A friend with mechanic experience heard noise and questioned whether lifter or rod. His advice was to add quart of tranny fluid at next oil change as this would lube all.

Would appreciate any thoughts you guys may have. Noise only when cold and then vanishes. Thoughts (besides turning up radio)?

thanks

[04 Unlimited]

Later model 4.0s seem to have sporadic lifter quality problems. Mine went south at about 50,000K; took the cam with it. Do some searching, you'll see the threads.

Mine didn't make noise every time I started the engine cold, it only "clattered" sporadically. Not sure whether rods would quiet when the engine warmed up unless the problem is piston slap, which I think is rare on the 4.0s. Generally, the lifters quiet down when pumped up with oil.

[corndogduff]

umm mine sounds almost like a diesel sometimes... should i be worried???

[Unlimited04]

I've got the same problem. Been doing it since new. The last time I went to the dealer they blamed it on the larger M1-301 oil filter...even tho its been happening since new.

Very common problem for newer 4.0Ls. Don't worry about it until the engine blows up.

[SilverBullot]

Same problem- sounds like a cammed out lawnmower. Pops took a look at it, said it could be a bad lifter, and an exhaust leak doesnt make it any quieter. Change the oil/filter religiously, use synthetic 10w-30. Sounded like a wannabe diesel since I got it 3 years ago...hasn't blown up yet lol