Rod knock or not???
07-13-2013, 03:45 PM
#19
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Year: 1996
Model: Cherokee
Engine: 1998 4.0L Inline 6
Got a recording of the noise?
Bent pushrod or bad rocker arm won't go away once it warms up.
Rod knock tends to be quieter at idle, louder at higher rpm, often worst when you decelerate. If you disconnect the plugs one by one a rod noise will get quieter or go away entirely when you deactivate the bad cylinder.
I'm gonna go with piston slap, keeping in mind that I'm 99% guessing, lol.
How can you tell your rockers are getting oil by the weight of the oil you are using?
You really have to pull the valve cover and look.
Bent pushrod or bad rocker arm won't go away once it warms up.
Rod knock tends to be quieter at idle, louder at higher rpm, often worst when you decelerate. If you disconnect the plugs one by one a rod noise will get quieter or go away entirely when you deactivate the bad cylinder.
I'm gonna go with piston slap, keeping in mind that I'm 99% guessing, lol.
How can you tell your rockers are getting oil by the weight of the oil you are using?
You really have to pull the valve cover and look.
07-13-2013, 04:28 PM
#20
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Year: 1991
Model: Cherokee
Engine: 4.0
Check the easy stuff first before worrying about the engine...
loose driveplate bolts (this will sometimes disappear in "D")
exhaust manifold leak (this will disappear as engine warms up)
loose driveplate bolts (this will sometimes disappear in "D")
exhaust manifold leak (this will disappear as engine warms up)
07-21-2013, 10:55 AM
#21
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Year: 1996
Model: Cherokee
Engine: 1998 4.0L Inline 6
ok so it doesnt go away in drive... and idk about the manifold but it doesnt sound like a manifold tick... i havent checked the driveplate bolts or the manifold bolts though... i will check the manifold bolts tomroow night when i fix my upper control arm bushings
07-21-2013, 01:01 PM
#22
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Year: 1991
Model: Cherokee
Engine: 4.0
Sometimes the exhaust manifold studs will break off after being subjected to umpteen heat/cold cycles but this is not too common.
More common is an exhaust manifold crack. With the engine cold, hook up a shop vac to the tailpipe in blower mode and pressurize the exhaust system...spray the exhaust manifold with soap bubble solution and check for leaks.
More common is an exhaust manifold crack. With the engine cold, hook up a shop vac to the tailpipe in blower mode and pressurize the exhaust system...spray the exhaust manifold with soap bubble solution and check for leaks.
07-21-2013, 07:28 PM
#23
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Year: 1996
Model: Cherokee
Engine: 1998 4.0L Inline 6
Sometimes the exhaust manifold studs will break off after being subjected to umpteen heat/cold cycles but this is not too common.
More common is an exhaust manifold crack. With the engine cold, hook up a shop vac to the tailpipe in blower mode and pressurize the exhaust system...spray the exhaust manifold with soap bubble solution and check for leaks.
More common is an exhaust manifold crack. With the engine cold, hook up a shop vac to the tailpipe in blower mode and pressurize the exhaust system...spray the exhaust manifold with soap bubble solution and check for leaks.
07-21-2013, 07:57 PM
#24
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Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Check the flexplate bolts..............
07-22-2013, 01:49 PM
#25
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Year: 1991
Model: Cherokee
Engine: 4.0
Check for an exhaust manifold leak (could be at the gasket and not necessarily a crack) and check the driveplate bolts anyway...this stuff is easy to do before tearing apart an engine in search of elusive internal noises.
Last edited by Carl48; 07-28-2013 at 07:08 PM. Reason: spelling
07-22-2013, 02:30 PM
#26
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Year: 1990
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Chipmaker says:
"Way more problems get solved by using your five senses under your hood rather than your ten fingers on a keyboard"
07-28-2013, 06:55 AM
#29
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Year: 1990
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