Another engine noise thread, your thoughts?
06-30-2010, 10:44 AM
#32
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Year: 1994
Model: Cherokee
Engine: 4.0
Manifold leak??
Also, it sounds like it is hitting about four beats per second. So, if you've got a six cylinder turning over at roughly 960 RPM, that is 16 revolutions per second (800/60) or so. Close enough for guesswork. This would mean the four beat per second sound is ONE cylinder making a sound four times per second if the engine is idling at 960.
This means, to me, that one wrist pin is wonky, one valve is hitting the top of the piston, one rocker arm is busted or tapping the end of the valve stem, one piston skirt, etc., etc.
But it sure sounds like a metallic chuff chuff chuff sound like exhaust squeezing out a little hole.
I like the idea of pulling the rocker cover. A leak-down test is cheap and easy...and not very messy, either.
Leak down test. That's the ticket. If you were nearby, I'd do it for you.
Last edited by CAEMI; 06-30-2010 at 10:50 AM.
06-30-2010, 11:17 AM
#34
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Year: 1993
Model: Cherokee
Engine: LEAKY NOISY 4.0
No thats not my video, but mine kinda sounds like that. I'm gonna try to take my own video soon but I'm not too computer savy.
06-30-2010, 11:29 PM
#36
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Year: 1997
Model: Cherokee
Engine: 4.0
I am moving to Chicago tomorrow lol. Addison to be exact. where do you wheel at? sorry for jacking your thread. i also have a very light tapping noise coming form the back of my motor/ front of tranny. Can barley hear it though.
07-01-2010, 07:51 AM
#37
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Year: 1993
Model: Cherokee
Engine: LEAKY NOISY 4.0
. My knock is definitely loud enuff to hear; sounds like a diesel when idling.I think I gotta check the flywheel a little better for cracks or something...... IDK, so damn aggravating; considering selling............
07-01-2010, 08:10 AM
#38
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Amsoil is full Syn. I too have 185k on the odom and have had no ill effects from running full syn in engine. Its up to you, Castrol syn blend is another good option if you want to stay away from a full syn. The only problem I see going full syn is that any leaks may become worse as the syn will 'slip' by the seals at a faster rate.
07-02-2010, 07:19 PM
#39
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Year: 1993
Model: Cherokee
Engine: LEAKY NOISY 4.0
Anyway I'm really startin to think the knock is comin from the tranny, but the damn sound travels so much ......???? Just checked the balancer today and its ok so..... still scratchin my head
07-03-2010, 07:25 AM
#41
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Year: 1993
Model: Cherokee
Engine: LEAKY NOISY 4.0
Go downtown one Saturday night ( Rush St. and Division St.), You'll really love it then............................ 
09-20-2010, 09:26 AM
#43
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Year: 1993
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Engine: LEAKY NOISY 4.0
Nope, its still doin it. But its running fine. I kinda gave up, probly just gonna run it til it blows. In the long run i think it will be cheaper and easier than buying and changing parts hoping the noise goes away......
09-20-2010, 10:32 AM
#44
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Year: 1997
Model: Cherokee
Engine: 4.0HO K&N FIPK2, Gibson chrome headers
Sup chicago people. I just moved into the area too. We should all go wheel. I'm locked and have recovery. <-wheelin' sales pitch
Back on topic.
I'm gonna have to go with CAEMI. That sound distinctively screams broken exhaust manifold, or loose/missing header bolt.
I had the same chuf chuf for 3 yrs, and it was in part due to a broken header stud @ #6 cyl. 2 weeks ago I said f**k it, and on saturday i replaced the head with a ported/polished reman w/ new lifters. Valvetrain didnt quiet down at all, but the manifold click was gone. I still have the infamous 4.0 rocker chatter, but it's what every 4.0 has without roller rockers.
My advice, pull the manifold (its really easy with 14mm on a few extensions and a u-joint), and take a look-see at your exhaust mani. You can usually see the crack. Broken or worn rubber motor mounts allow too much shifting of the manifold, and that can easily cause a crack in the stocker. If it's stock it's most likely cracked where cyl 1-3 meets 4-6, but it could be anywhere.
my 2/100
Back on topic.
I'm gonna have to go with CAEMI. That sound distinctively screams broken exhaust manifold, or loose/missing header bolt.
I had the same chuf chuf for 3 yrs, and it was in part due to a broken header stud @ #6 cyl. 2 weeks ago I said f**k it, and on saturday i replaced the head with a ported/polished reman w/ new lifters. Valvetrain didnt quiet down at all, but the manifold click was gone. I still have the infamous 4.0 rocker chatter, but it's what every 4.0 has without roller rockers.
My advice, pull the manifold (its really easy with 14mm on a few extensions and a u-joint), and take a look-see at your exhaust mani. You can usually see the crack. Broken or worn rubber motor mounts allow too much shifting of the manifold, and that can easily cause a crack in the stocker. If it's stock it's most likely cracked where cyl 1-3 meets 4-6, but it could be anywhere.
my 2/100
