Curious if anyone else's 4.0 knocks like a jehova until it is completely warmed up?? Mine chatters/knocks like a diesel, but after driving for 20-30 minutes it gets considerably quieter. Still a bit noisy at temp, but not nearly as bad.

Oil pressure is perfect, running 10w30 oil.

Thoughts/Opinions??

After watching a few youtube video's to show what im talking about, I came across this one. Sounds 100% identicle to mine..


Skip to 1.40


She's got 170,000 miles on her. Good for 100k more? Lol

And I just noticed there is another thread on this issue. My bad

Are you manual trans try pushing down clutch pedal.

most 4.0s have lifter tick, also another area very likely could be the exhaust manifold, the heat makes it expand so thats why you only hear it when its cold.

@ about 1:18 he clutches it, no change.

could be sticky lifter/s have you tried sea foam in the manifold via break master cylinder vac hose? that can do wonders.. just get the hose off, keep rpms steady around 3k and pour about 1/3 a can in slowly. cheap and easy. it doesnt sound like a flexplate issue, which is also pretty common.

Mine does pretty much the same thing. Has been for 50k miles, with 216k on the clock. It does sound like a small diesel engine... I think it's just valvetrain noise, but it could be something more serious.

Rotella 15-40 and a quality filter (not fram) are your friend.

Pretty much all 4.0's have some amount of piston slap which along with noisy lifters makes our engines sound very diesel like.

15w40 made mine much louder. I put 5w30 back in it and it's quiet as a mouse again.

also putting seafoam in through a vacuum hose wot help the lifters out at all.

There wouldnt be any Flexplate with a manual. There would be a Flywheel.

There wouldnt be a Flexplate with a manual, it would be a Flywheel.

15W-40 is too thick.

5W/10W-30 is just right.

It depends on what year 4.0 and how it is worn to determine what weight and type of oil should be used in it.

I would put a 0w-30 or 5w30 in my 2001 SilverStone Metallic XJs 65,212 mile 4.0 with confedence, but not in my 87s 297,518 mile 4.0, I use HD30 or 10w-40, Diesel 15w-40 oils in her original 1st year 4.0

I would say a Conventional(Dinosaur) 10w-30 is just about right for most any 4.0, mmm is that why its the Preferred and recommended oil for use in the 4.0?