Valve clatter coming off freeway?
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Senior User
Joined: Jul 2007
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Valve clatter coming off freeway?
I got about 1200 miles on my new motor now. Driving around town and back roads no noise. But if I drive down the free way 2400-2500 rpm for about 5 miles or so steady and come off a off ramp to a stop the top end is just a clattering. take off and stop sign not but 200 ft from that stop again no noise at all. So I guess my question is why would the top end be clattering after a couple of miles of constant 2500 rpms? I can drive for a 50 miles of 2000 rpms and not a sound. Thanks fro any help
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Senior User
Joined: Jul 2007
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I am going to put on a oil cooler eventually, and I have 55-57 psi of oil pressure when cruising around. I do run a little thicker oil. I am wondering if maybe the roller rockers are slipping off top of valve and loosening up, or when coming to stop top of motor is starving for oil. but when you take back off and drive for just a little while and stop again it is back to quite. I do think it is more of a oil problem because most of the time it is more towards 90 degrees then 60 degreees.
Post Fiend
Joined: Dec 2007
Posts: 8,521
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From: Lost
Sounds to me like the lifters are collapsing during the extended higher RPM use. Oil pressure certainly sounds plenty high enough. Perhaps the oil is just a bit too thick to flow into the lifters fast enough at higher RPM.
Of course, it could be as simple as the valve lash being just a hair too loose, and after returning to idle, the lifters can pump back up enough to quiet them down.
Of course, it could be as simple as the valve lash being just a hair too loose, and after returning to idle, the lifters can pump back up enough to quiet them down.
Lead Driver
Joined: Mar 2008
Posts: 7,182
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From: Near Los Angeles
It seems, and correct me if I am wrong here, that a build like mine, or AJ's, where he is about doubling the oe horse power, puts quite a demand on the oe oiling system. Shouldn't the oiling system, just like installing a tranny cooler for towing with an auto trans, also be up-graded to deal with the greater demands forced upon it?
I believe I may experiment with chopping up a pan and fashioning an expansion 'fin' on the bottom, copied from Summit.
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