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Unread 08-20-2013, 04:57 PM   #1
cody024
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1997 zj 318 engine question

What would cause a 318 v8 to have high oil pressure (60-70 psi) and a knocking sound. No loss of power at all, no missing and no cel. Oil is full as well. Thanks

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Unread 08-20-2013, 05:17 PM   #2
dnuccio
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knocking and high oil pressure dont go together. usually you have one or the other. have you hooked up a mechanical gauge to see if the oil pressure is truly that high? high oil pressure is good BTW, it means your bearings and clearances are in good shape. are you sure this "knocking" isnt just the normal mechanical noise of the engine?
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Unread 08-20-2013, 05:20 PM   #3
cody024
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I might have it hooked up to a mechanical gauge soon. The jeep sounds like a diesel lol. I can take a video with my iPhone if you'd like.
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Unread 08-20-2013, 05:56 PM   #4
dnuccio
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are you sure its an actual knock, and not a misfire on one or more cylinders? video would be great
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Unread 08-21-2013, 12:40 AM   #5
LunaMoona
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Quote:
Originally Posted by cody024 View Post
What would cause a 318 v8 to have high oil pressure (60-70 psi) and a knocking sound. No loss of power at all, no missing and no cel. Oil is full as well. Thanks
60-70 psi at cold idle is within specification. 60 psi at operating temperature under normal driving conditions is also within specifications.
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Unread 08-22-2013, 03:22 PM   #6
erisbrow
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You arent using Premium fuel are you?
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Unread 08-22-2013, 03:31 PM   #7
cody024
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It's def a knock, and heck no lol. At 12 mpg I'm lucky I can afford 87 octane
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Unread 08-22-2013, 03:33 PM   #8
WhiteOut
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You arent using Premium fuel are you?
100% Irrelevant
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Unread 08-22-2013, 04:12 PM   #9
zj97ltd
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Just throwing out thoughts here... Would a blockage in oil passages say, near the cam bearings, boost oil pressure while starving certain components of oil?
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Unread 08-22-2013, 05:28 PM   #10
dnuccio
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i doubt a blockage would increase oil pressure
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Unread 08-22-2013, 09:31 PM   #11
Muncie4sp
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was the motor recently rebuilt?! a forgotten oil galley plug could be the issue.
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Unread 08-23-2013, 07:22 PM   #12
cody024
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Motor has 84,000 miles on it. gonna have it looked at soon
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