Noise underneath valve cover

AZDANNO04

MEMBER
1998 NISSAN SENTRA
1.6L
4 CYL
2WD
AUTOMATIC
230,000 MILES

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.

4 Replies

JACOBANDNICKOLAS

MECHANIC
108,269 POSTS

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

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Monday, February 15th, 2021 AT 4:36 PM

KASEKENNY

MECHANIC
18,907 POSTS

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

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Monday, February 15th, 2021 AT 4:40 PM

AZDANNO04

MEMBER
267 POSTS

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.

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Thursday, March 4th, 2021 AT 8:32 PM

KASEKENNY