C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

C4 87 engine noise

Old 06-05-2019, 10:18 AM
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Default C4 87 engine noise

Hi guys. Look here if anyone had a similar problem. C4 87 unusual periodic knocking around the top of the engine.
The rule is that the warmer the more often and the louder.Characteristic also that, for example, on slow speed sporadically, but after a slight gasification, it is immediately audible. On the movies you can hear every now and then such additional clicks. The bottom of the engine silence, listened to with a stethoscope. The most audible around the valves and I have the impression that the warmer the more from the front of the engine. The oil pressure is OK. Valve lifter? push rod? rocker arm? or maybe it's a typical sound and someone has already done it? Timing stretched? mileage 97000. I set the valves according to the instructions. Take a look.

Last edited by Blackwater15; 06-05-2019 at 10:31 AM.
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Old 06-06-2019, 10:18 AM
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Old 06-06-2019, 05:17 PM
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Are u sure you have a roller motor?
Are u using oil additives?
Since they took the high pressure lubricant additives out of the oil, your cam may be going flat.
They sell the additives at your local auto parts store, but it might be too late!

Phosphorus and zinc no longer come in regular oil, since for the most part, flat tappet cams have gone away since 1989.

Last edited by coupeguy2001; 06-06-2019 at 05:18 PM.
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Old 06-07-2019, 01:16 AM
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Nothing changes. I think it's a valve lifter . This is the original 87 engine. I do not use additives for oils. You think you need it? My oil is of good quality

Last edited by Blackwater15; 06-07-2019 at 01:22 AM.
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Old 06-12-2019, 10:27 AM
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'87 L98 was the first with roller cam.
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Old 06-12-2019, 08:28 PM
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I have noticed the same exact thing with my 1987. I thought it could be a loose rocker and it only does it every now and then if I gas it up to hard. It almost sounds like a header gasket leak. but it is coming out of the valve cover. Let me know if you figure it out. Thanks, gary
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