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Knocking sound from engine (Mitsubishi eclipse)

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New User

May 12, 2018, 1:48 AM

Post #1 of 2 (436 views)
Knocking sound from engine (Mitsubishi eclipse) Sign In

I have been hearing a knocking sound for about 4k miles, it was a lot quieter before but has gotten increasing louder. Not sure what is it, piston slap maybe? Almost sounds like a jack hammer but a lot quieter. It doesn't go away even when engine is warm / hot. I have 110k miles. (Car is a 4cyl Mitsubishi eclipse)

(Will post a video when I get home)

Tom Greenleaf
Ultimate Carjunky / Moderator
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May 12, 2018, 3:25 AM

Post #2 of 2 (421 views)
Re: Knocking sound from engine (Mitsubishi eclipse) Sign In

You've let this noise go on for 4,000 miles without finding the cause? - ! Sure hope it is/was something external like an accessory or could be real trouble now.
Textbook "Piston Slap" is usually easy to diagnose as a heavy, dulled metallic knock most noticeable under load and while cold. Early on that would go away as engine warms up and may or may not pick on one cylinder or up to all.

In your video when you can try to rule out an accessory first any belt driven items if you can aim at pulleys for the video for alignment of belt(s) as well.

Noises are always tricky not witnessed in person try your best. Add any known history of overheats, low on oil and major work prior to any noise that might be a cause and just maybe can come up with a good guess what is likely and what to do that should have been done that 4,000 miles ago!


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