Noise underneath valve cover

1998 NISSAN SENTRA
230,000 MILES • 1.6L • 4 CYL • 2WD • AUTOMATIC
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AZDANNO04
I did replaced the upper tensioner and after that started up the car three times and it sounded quiet as a well tuned sewing machine. Then all the noise again underneath the valve cover. I did a compressor check. The first cylinder was 20 PSI lower than the remaining cylinders. When I replaced the upper tensioner. I took a glance at the sprockets majority from I was to see a few teeth were a bit worn but not major worry. I asked a few and they think it's either the camshaft, connecting rod, enobe.
Feb 15, 2021 at 2:10 AM
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JACOBANDNICKOLAS
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Hi,

Is it possible for you to record it and upload it for me to hear? Is it a ticking, knocking, raping or how would you best describe it? Did you inspect the cams when it was apart as well as valve springs?

Let me know.

Joe
Feb 15, 2021 at 4:36 PM
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KASEKENNY
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Can you get a recording of this noise? If you have lower compression on a cylinder then you could have a valve issue causing this noise and the lower compression.

https://www.2carpros.com/articles/how-to-test-engine-compression

Next thing to do is run a cylinder leakage test on that cylinder to find out where the compression is going.

Here is a video that will help with this:

https://www.youtube.com/watch?v=WHli-wLy9_o

I suspect you will find the air is escaping from the intake or exhaust which points to one of the valves. So let me know if you have questions and if you can get that recording. Thanks
Feb 15, 2021 at 4:40 PM
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AZDANNO04
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Will do, I just noticed that the cross arm member that's underneath the vehicle that's in the middle of the vehicle where the rear engine mount is mounted on the two bolts towards the back of the car were backing themselves out. I ordered new bolts that would have fresh threads to bite when tightening but towards three quarters tightening it would spin loosely. Figured I would have to use tap and dye set M10 1.25 before driving the vehicle.
Mar 4, 2021 at 8:32 PM
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KASEKENNY
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Sounds great. Thanks for the update. Let us know how you make out. Thanks
Mar 5, 2021 at 6:47 PM
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