Engine Knock at Idle
CF Veteran
Joined: Aug 2011
Posts: 10,489
Likes: 24
From: Nor-Cal Coast
Year: 90,84
Model: Cherokee
Engine: 4.0,2.5
Long story Bubba. Sheriffs will lie to you, and will purger themselves under oath. Sad to see a new Deputy do it, obviously coached by his Sargent on how to lie, but not that good...., yet. I went 300 miles and moved a cab-over camper out of the yard I've been using since 1975. Anyway, that sounds sweet! Nice job.
Tact, do I hear a hiss, like a vacuum leak?
Tact, do I hear a hiss, like a vacuum leak?
Thread Starter
Junior Member
Joined: Aug 2012
Posts: 50
Likes: 0
From: West Richland, WA
Year: 1998
Model: Cherokee
Engine: I6
when I changed out the exhaust manifold I installed one with the accordion joints on it. Haven't noticed any cracks so far!
Thread Starter
Junior Member
Joined: Aug 2012
Posts: 50
Likes: 0
From: West Richland, WA
Year: 1998
Model: Cherokee
Engine: I6
I put "Cherokee knock" into U-Tube search and found ME, (11 down)>> 4.0 Cherokee Jeep engine knock..... rod - YouTube
Not identical, but similar to yours. It's been doing that for well over 10 years. It's part of the reason the previous owner sold it to me in 02. Please use a Wix filter. or napa Gold, (same thing). Not Fram, the "Orange Can Of Death"
Not identical, but similar to yours. It's been doing that for well over 10 years. It's part of the reason the previous owner sold it to me in 02. Please use a Wix filter. or napa Gold, (same thing). Not Fram, the "Orange Can Of Death"
Thread Starter
Junior Member
Joined: Aug 2012
Posts: 50
Likes: 0
From: West Richland, WA
Year: 1998
Model: Cherokee
Engine: I6
Long story Bubba. Sheriffs will lie to you, and will purger themselves under oath. Sad to see a new Deputy do it, obviously coached by his Sargent on how to lie, but not that good...., yet. I went 300 miles and moved a cab-over camper out of the yard I've been using since 1975. Anyway, that sounds sweet! Nice job.
Tact, do I hear a hiss, like a vacuum leak?
Tact, do I hear a hiss, like a vacuum leak?
Thread Starter
Junior Member
Joined: Aug 2012
Posts: 50
Likes: 0
From: West Richland, WA
Year: 1998
Model: Cherokee
Engine: I6
I just want to say thank you to all that have replied to this. It's great to have people I don't even know helping out with something that isn't a major issue. I've learned so much off of this forum and is what actually got me interested into taking care of and modding my xj. Couldn't have gotten this far, and trust me I will be taking her farther, without you guys. THANKS!
CF Veteran
Joined: Dec 2012
Posts: 4,169
Likes: 6
From: York, PA
Year: 1998
Model: Cherokee
Engine: 4.0
I put Rotella T6 5w40 full synthetic in mine and it quieted down my 4.0 a lot. Slight little knock/lifter tap as others have mentioned comes natural with the 4.0 Runs fantastic.
CF Veteran
Joined: Sep 2013
Posts: 1,552
Likes: 7
From: California
Year: 91
Model: Cherokee
Engine: 4.0
Long story Bubba. Sheriffs will lie to you, and will purger themselves under oath. Sad to see a new Deputy do it, obviously coached by his Sargent on how to lie, but not that good...., yet. I went 300 miles and moved a cab-over camper out of the yard I've been using since 1975. Anyway, that sounds sweet! Nice job.
Tact, do I hear a hiss, like a vacuum leak?
Tact, do I hear a hiss, like a vacuum leak?
Junior Member
Joined: Jun 2013
Posts: 89
Likes: 0
From: SW Virginia
Year: 1999
Model: Cherokee
Engine: 4.0L
I recently switched to T6 and run a Mopar filter.
I have that same sound that DFlintstone posted, but also I have some valve train noise as well that sounds like the rocker might need to be retorqued. It sounds like a muffled diesel a bit. Nothing to terribly loud, but I would like to quiet it down a bit. Haven't had a 4.0 as loud as this one.
CF Veteran
Joined: Aug 2011
Posts: 10,489
Likes: 24
From: Nor-Cal Coast
Year: 90,84
Model: Cherokee
Engine: 4.0,2.5
I'm really at a loss. I thought rod at first, but no way could a rod hammer like that for nearly 150K (Had 140, 278K now). Crank end play maybe? RRR. Just a bad lifter? but only one out of 12 for so long? It was extra loud that morn, had just parked at full temp, than came out 1/2 hr later, was below freezing. Some things cooled, and some didn't. Anyway, I've heard plenty of others with the same knock. My issue is the 4.0 connected to the AW4 is tearing all the metal connected to it to bits! On uneven ground my hatch can come down on a tail-light. (cracks out board of the hatch hinges).There are also cracks top-rear of the passenger door frame. 
Yea Bubba...I never, ever did anything to harm or bother anyone. Born and raised here, not going anywhere. It's not a "Justice System", it's a framework of laws, more and more BOUGHT by those with financial gain as motive.
Yea Bubba...I never, ever did anything to harm or bother anyone. Born and raised here, not going anywhere. It's not a "Justice System", it's a framework of laws, more and more BOUGHT by those with financial gain as motive.
CF Veteran
Joined: Sep 2013
Posts: 1,552
Likes: 7
From: California
Year: 91
Model: Cherokee
Engine: 4.0
Repeat business for them. What happened to me. Fines paid off. Lets go get him again. He pays his bills.... Even got one for my dog not being on a leash in My own fenced in yard.
Thread Starter
Junior Member
Joined: Aug 2012
Posts: 50
Likes: 0
From: West Richland, WA
Year: 1998
Model: Cherokee
Engine: I6
Rotella is a diesel engine oil correct? I thought that was bad for gasoline engines? and why full synthetic? Anyone else have any comments on this?
Junior Member
Joined: Mar 2014
Posts: 75
Likes: 0
From: Mid-Mich.
Year: 1995
Model: Cherokee
Like the other guys said, it sounds like any other 4.0 I've ever heard. Mine has made those same noises since I drove it off the lot 20 years ago. 4.0 are not quiet engines, they have kind of a knocking noise at idle that I've heard in every XJ I've ever heard. Is this your first 4.0 ? The next time you pull up to a light next to a similar jeep, roll down your windows and see what I mean. That's just the way they are.
Thread Starter
Junior Member
Joined: Aug 2012
Posts: 50
Likes: 0
From: West Richland, WA
Year: 1998
Model: Cherokee
Engine: I6
Like the other guys said, it sounds like any other 4.0 I've ever heard. Mine has made those same noises since I drove it off the lot 20 years ago. 4.0 are not quiet engines, they have kind of a knocking noise at idle that I've heard in every XJ I've ever heard. Is this your first 4.0 ? The next time you pull up to a light next to a similar jeep, roll down your windows and see what I mean. That's just the way they are.
Thread Starter
Junior Member
Joined: Aug 2012
Posts: 50
Likes: 0
From: West Richland, WA
Year: 1998
Model: Cherokee
Engine: I6
I'm really at a loss. I thought rod at first, but no way could a rod hammer like that for nearly 150K (Had 140, 278K now). Crank end play maybe? RRR. Just a bad lifter? but only one out of 12 for so long? It was extra loud that morn, had just parked at full temp, than came out 1/2 hr later, was below freezing. Some things cooled, and some didn't. Anyway, I've heard plenty of others with the same knock. My issue is the 4.0 connected to the AW4 is tearing all the metal connected to it to bits! On uneven ground my hatch can come down on a tail-light. (cracks out board of the hatch hinges).There are also cracks top-rear of the passenger door frame.
Yea Bubba...I never, ever did anything to harm or bother anyone. Born and raised here, not going anywhere. It's not a "Justice System", it's a framework of laws, more and more BOUGHT by those with financial gain as motive.
Yea Bubba...I never, ever did anything to harm or bother anyone. Born and raised here, not going anywhere. It's not a "Justice System", it's a framework of laws, more and more BOUGHT by those with financial gain as motive.