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Another Engine Knocking Thread

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Another Engine Knocking Thread

 
Old 03-25-2019, 05:11 AM
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So a little background I recently purchased this AP1 S2000 from a used dealer that was asking such a low price that I bought it with this sound. Originally I thought it was the valve lash, however I just adjusted that to within spec yesterday and the knock is still present. The car has an unknown maintenance history but it has 65k miles on it, all vin numbers intact, and completely bone stock. While under the hood for the valve lash adjustment I also inspected the valve retainers and they too were mint. To describe the sound, the knock is present on a cold start, fades when car warms up, then comes back as the motor reaches operating temperature. Knocking is constant with engine rpms no matter accelerating or decelerating. While cruising the knock is fairly subdued. (Maybe just can't hear it over the intake noise. Here is a short clip of it.

Any and all contributing answers are welcome.
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Old 03-25-2019, 11:09 AM
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That’s a pretty loud engine noise. Have you done a compression test on it yet to see if there are any low cylinders? Also would advise an oil pressure test to see if your pressure is low. Unfortunately the Honda oil pressure light only comes on when it is extremely low and damage has already been done.
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Old 03-25-2019, 11:27 AM
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Originally Posted by outeiroj View Post
That’s a pretty loud engine noise. Have you done a compression test on it yet to see if there are any low cylinders? Also would advise an oil pressure test to see if your pressure is low. Unfortunately the Honda oil pressure light only comes on when it is extremely low and damage has already been done.
Thanks, will do although funny thing is it runs just fine even with the noise, but I'll definitely check the oil pressure then the compression. If it ends up being the piston rings is there a set that is preferable? Also I assume if low oil pressure I'll have to check the main caps and rod bearings? Or would I be able to get away with shimming the oil pump like other hondas?
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Old 03-25-2019, 12:33 PM
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First, I doubt that the rings are making that sound. Second, take the oil filter off and open it up to see if it has metal debris in it. I would not run it till I looked at the oil filter, no need to warm the oil up first because if it is a bearing you will see it in the filter.

Rod
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Old 03-25-2019, 04:53 PM
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Just to rule-out any pulley or belt issues --- briefly remove the accessory belt and listen to car idle.

Good luck with your fix!
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Old 03-25-2019, 05:25 PM
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Originally Posted by rrounds View Post
First, I doubt that the rings are making that sound. Second, take the oil filter off and open it up to see if it has metal debris in it. I would not run it till I looked at the oil filter, no need to warm the oil up first because if it is a bearing you will see it in the filter.

Rod
Definitely will do, currently it has a non OEM filter on it and I heard those can be problematic for oil flow. So I was going to change that and the unknown oil in it


Originally Posted by windhund116 View Post
Just to rule-out any pulley or belt issues --- briefly remove the accessory belt and listen to car idle.

Good luck with your fix!
Sounds like a quick one I can do tonight before work. If the bearings are shot, how do these cars take to lightweight pulleys? Just looking for a little dress up as long as it doesn't hurt performance or reliability.

To all who have assisted so far, I'm grateful. This is my first Honda ever, but I'm no stranger to working on them. I'll upload a cold start video with some light revving. Honestly to me I doesn't sound like the typical rod knock because it's too consistent with the engine rpm and it is still present and constant under deceleration. I also tried the method where you pull the coil packs on each cylinder to reduce the load on the piston and rod and listen for a difference. When done there was no discernible difference in knock amplitude or frequency.

Again thank you all for your help so far. Today was rainy so let the tests begin tomorrow.

-Kurt
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Old 03-25-2019, 05:32 PM
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I'd just get a new pulley with bearings inserted. But, I guess you can press in new bearings, if the pulley is still okay.

IME, rotating the pulleys, by hand --- with belt off --- usually narrows down the rough ones.
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Old 03-25-2019, 05:50 PM
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That does not sound like rod knock to me, check the exhaust/header for leaks
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Old 03-25-2019, 10:54 PM
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An oil analysis might be a quick and good option to rule out shot bearings.

Mine has had a knock-like sound on cold start which turns into a slight ticking when at operating temperature since I've bought it 30.000km (~ 18.600miles) ago.

Oil analysis showed no increased wear on any metals and the sound hasn't changed at all during my ownership.
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Old 03-26-2019, 08:02 AM
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Almost sounds like a number 4 cylinder liner, hard to say.

With the engine running, disconnect the number 4 INJECTOR. See if the noise lessens.
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