That sounds like your torque converter is gone bad... i had the same issue... but it didnt knock that bad... it sounded very similar though... i replaced it... and it went away
@srpope80 Your best bet is to visit a good machine shop and have the old parts rebuilt/rebored. Bronze valve guides are best, as they don't react with valvestem chromium. Powder metal valve seats are good quality. Of course, Stellite seats and stellite faced valves offer superior wear resistance. Highly important to check valvetip geometry. Sometimes a valve is installed offset of original position. Pedestal rockers have ovoid hole and allow fore aft adjustments, to perfect tip geometry.
the 4.0 is not know for a cracked manifold!its the number six cylinder crank bearing try lucas oil should quit it right up over time and change every 3,000
@AutumMorin5 Are you kidding me? Yes they are, they are notorious for cracked exhaust manifolds due to the fact there is no flex coupling in the exhaust, it is one solid run all the way back. All 5 I've owned have had cracked manifolds.
That sounds very similar to my 99 WJ. Pull the oil pan off, see if there is any pieces of metal that dropped down. Also take a flashlight and shine it up into each "slug", check to make sure each piston is there in its entirety. Usually when it happens its number 6 cylinder, the one closest to the firewall. The coil packs are kinda known for this problem.
I have a '96 xj and it sounds the same. I have been looking for the reason for this sound. A few people I have talked with who know the 4.0 say this is normal. It has sounded this way for a few years . Still runs great. Still bothers me though.
@ematuzsan Finally figured out the issue... Piston Slap... Pistons 1/2/&4 skirts all rock back and forth when they are at BDC. The rest wouldn't do it no matter what position I rotated the engine in....
Just replaced an engine in a 2000 xj with the same noise ended up being a piston skirt cracked and broken after close inspection all the skirts had hairline cracks!! 133,700 miles
@donbrenstage No I still haven't figured it out. I want to drop the oil pan soon to check for a cracked piston skirt, but haven't had the time... I really believe it's a valve lifter as when you feather the throttle slightly, the tick goes away when the valve floats....
@srpope80. You might have it fixed all ready, But does it only do it when its wormed up because my 91 Jeep Cherokee 4.0L limited does that ticking too. My guess its probably the Lifters.
@WedidLandONtheMOON No I don't have it fixed yet; it is the loudest when the engine is cold, but when it warms up there still is a slight tick. Other than that, the Jeep runs and drives great....
sounds just like the knock in my 2000 mazda 4.0 v6...i think it might be a lifter hitting your vaulve, theres a little pin hole below the lifter that gets dirty and will make so theres not enough preshure to hold the lifter from hitting the vaulve, thats what it was in my truck but im not sure. good luck
same noise on my 2000 cherokee... been like that since i bought it at 50k... The 4.0"s are loud engines... My jeep also has very loud valves... sounds like I have a bad exhaust manifold leak but i dont...
Have a listen to my videos on my youtube page and you'll see your's sounds alot like mine. I would suggest you try removing your belt for one run to make sure it's not an accessory or idler pulley. I'm on JeepForum and other forums trying to figure out the same noise. Mine is in a 2001 WJ I6. Let me know what you find out.
That sounds like your torque converter is gone bad... i had the same issue... but it didnt knock that bad... it sounded very similar though... i replaced it... and it went away
JGonzo117 4 days ago
Rebuilding the engine with proper piston/cyl wall clearance will prevent this from happening again.
seapeddler 3 weeks ago
@seapeddler I agree; I think I'm going to go with a rebuilt engine. Have you had any experience with rebuilt engine suppliers?
srpope80 3 weeks ago
@srpope80 Your best bet is to visit a good machine shop and have the old parts rebuilt/rebored. Bronze valve guides are best, as they don't react with valvestem chromium. Powder metal valve seats are good quality. Of course, Stellite seats and stellite faced valves offer superior wear resistance. Highly important to check valvetip geometry. Sometimes a valve is installed offset of original position. Pedestal rockers have ovoid hole and allow fore aft adjustments, to perfect tip geometry.
seapeddler 3 weeks ago
Comment removed
jeepwranglers 2 months ago
the 4.0 is not know for a cracked manifold!its the number six cylinder crank bearing try lucas oil should quit it right up over time and change every 3,000
AutumMorin5 3 months ago
@AutumMorin5 Are you kidding me? Yes they are, they are notorious for cracked exhaust manifolds due to the fact there is no flex coupling in the exhaust, it is one solid run all the way back. All 5 I've owned have had cracked manifolds.
Bags751 2 months ago
Try inspecting the flex plate
tylerspyler2 3 months ago
That sounds very similar to my 99 WJ. Pull the oil pan off, see if there is any pieces of metal that dropped down. Also take a flashlight and shine it up into each "slug", check to make sure each piston is there in its entirety. Usually when it happens its number 6 cylinder, the one closest to the firewall. The coil packs are kinda known for this problem.
DieselSlug 4 months ago
I have a '96 xj and it sounds the same. I have been looking for the reason for this sound. A few people I have talked with who know the 4.0 say this is normal. It has sounded this way for a few years . Still runs great. Still bothers me though.
grimheathen 7 months ago
that's bad and it aint no manifold
butch93105 8 months ago
Hi there, did you pin point the issue? I have the same knock.
ematuzsan 8 months ago
@ematuzsan No, still knocking....
srpope80 8 months ago
@ematuzsan Finally figured out the issue... Piston Slap... Pistons 1/2/&4 skirts all rock back and forth when they are at BDC. The rest wouldn't do it no matter what position I rotated the engine in....
srpope80 2 months ago
Sorry for such a long delay in replying I did the whole engine... All the other pistons had stress cracks at the wrist pins.
00CherokeeXJ 8 months ago
Sounds like it might be a cracked manifold the IL-6- 4.0 is known for this.
goldgeter123 9 months ago
Just replaced an engine in a 2000 xj with the same noise ended up being a piston skirt cracked and broken after close inspection all the skirts had hairline cracks!! 133,700 miles
00CherokeeXJ 11 months ago
@00CherokeeXJ Did you replace the entire engine or repair the broken pistons? Wow! That is crazy. What do you think caused that?
srpope80 11 months ago
every 4.0 i have heard sounds just like this
cbr6864 1 year ago
did u find out what this was?
donbrenstage 1 year ago
@donbrenstage No I still haven't figured it out. I want to drop the oil pan soon to check for a cracked piston skirt, but haven't had the time... I really believe it's a valve lifter as when you feather the throttle slightly, the tick goes away when the valve floats....
srpope80 1 year ago
@srpope80. You might have it fixed all ready, But does it only do it when its wormed up because my 91 Jeep Cherokee 4.0L limited does that ticking too. My guess its probably the Lifters.
WedidLandONtheMOON 11 months ago
@WedidLandONtheMOON No I don't have it fixed yet; it is the loudest when the engine is cold, but when it warms up there still is a slight tick. Other than that, the Jeep runs and drives great....
srpope80 11 months ago
sounds just like the knock in my 2000 mazda 4.0 v6...i think it might be a lifter hitting your vaulve, theres a little pin hole below the lifter that gets dirty and will make so theres not enough preshure to hold the lifter from hitting the vaulve, thats what it was in my truck but im not sure. good luck
jws6221 1 year ago
COULD be piston slap.. or a cracked flywheel, the bolts on the flywheel come loose somtimes and sound the same,only knocks at idle....
00xjclassic 1 year ago
same noise on my 2000 cherokee... been like that since i bought it at 50k... The 4.0"s are loud engines... My jeep also has very loud valves... sounds like I have a bad exhaust manifold leak but i dont...
00xjclassic 1 year ago
Have a listen to my videos on my youtube page and you'll see your's sounds alot like mine. I would suggest you try removing your belt for one run to make sure it's not an accessory or idler pulley. I'm on JeepForum and other forums trying to figure out the same noise. Mine is in a 2001 WJ I6. Let me know what you find out.
jclaudii 1 year ago