4.0 engine noise
 

the other day my engine developed a noise in it. i was climibing a large grade on the hiway in 3 rd gear at 3200 rpm when i crested the top i heard a noise it kind of sound like a tapping noise. when i got home i lifted the hood and heard it at idle. yesterday i changed the engine oil and filter added one quart of marvel mystrey oil and 4.5 qts of valvoline 50 weight racing oil. i started it up and let it run for a while it sounded like it got better but noticed it real loud as soon as the engine starts and as soon as the engine runs for a while it seems to go away. i took the valve cover off and made sure all the rocker arms looked like they were traveling all the same except for the lift diffrence between the intalke and exhaust. i checked all the rocker bolts they were tight. i started the engine with the valve cover off and saw all the pushrods rotaing except 2. i took those 2 out to make sure they werent bent i blew threw them and cleaned them i reinstalled them they still didnt rotate like the others but didnt run it for very long due to the mess it was making. its a 88 4.0 with fuel injection and has 194k miles on it. please help.

Possible rod knock on the rear cylinders - might try pulling the spark plug wires off each cylinders to see any change noise. Also check fly wheel for cracks they will sound like a knock in a pull and when first started up at different temp.

i did the cylinder drop test and no diffrence so i couldnt tell what cylinder it was. is there a way to check the flywheel without pulling the trans?

Could be lifters, or possibly a cracked piston.

you must be talking about an automatic flex plate i have a 5 speed i wouldnt think that big manuel flywheel would crack.

i have the same knock i think you are talking about on my 96. it has not caused me any issues other than the noise at idle.i wish i could help but as i find stuff out i will let you know

i just went through this, all symptoms of bad lifter....but I was wrong way wrong....... this pic of my #3 piston I found this on top of the front axle.

you must of had a wrist pin seize up on you and the piston broke throwing it out the side of the block or oil pan.

something like that....it went through the block.....it doesnt matter now lol