Engine knock

2003 LEXUS ES 300
170,000 MILES • 3.3L • 6 CYL • 2WD • AUTOMATIC
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NATHAN5434
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Hello, so I went for an oil change today and the guy told me he hears an engine knock... I never heard any noise from my car so I'm not sure what he is hearing. And he said my oil was sludgy. I've been changing my oil every 3,000 miles to semi synthetic. Should I get it checked out? Or is there a way to help it in case there is a engine knock? Or just let it be?
Apr 2, 2021 at 3:50 PM
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I-SMOGEM
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Hi Nathan,

An engine knock can be a symptom of something serious that is internal engine. But, there are many things that can mimic that type of noise (bad harmonic balancer for one, valve tappets is another common one).

I certainly would suggest you get it checked and diagnosed. I used a stethoscope where the 'drum' was replaced with a hollow metal tube. This made it easy to determine where the noise was coming from as side noise doesn't make it in as easily as noise directly at the end of the tube.

I would also ensure that your PCV system is working properly -- part of the oils job is to absorb fuel that makes it into the crankcase, and then the PCV system removes it. If the bypass fuel isn't removed by the PCV, that will cause the oil to be fuel saturated and then could get 'sludgy'.

After it's diagnosed, recommendations on where to go from there are important. Would love to hear what you find out.

Glenn
Apr 2, 2021 at 5:05 PM
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NATHAN5434
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Hi Glenn,

Okay, perfect I'll keep you updated.
Thank you.
Apr 3, 2021 at 12:29 AM
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JACOBANDNICKOLAS
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Hi,

I noticed it has been a couple of days since we heard from you. I was wondering if you have made any progress. Also, I wanted to add a link you may find helpful. Take a look through this link.

https://www.2carpros.com/articles/engine-noises

Also, if you could record the noise and upload it for us to hear, it may be helpful.

Let us know,

Joe
Apr 5, 2021 at 6:17 PM
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I-SMOGEM
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Well, someone else jumped in since we hadn't heard from you, so I'm checking in. What's the latest info? Anything new to give us?

Hope all is well. Glenn
Apr 18, 2021 at 9:53 PM