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Old April 12th, 2018, 09:06
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How much knock is too much knock?

1998 XJ
4.0I6
Head swap in December. About 6k put on it since.
Recent oil change less than 500 miles ago

Started up the XJ and it seems just a bit too knocky. They always make some noise when they are cold but this sounds like a light diesel. It did go away once the engine was at running temp and no fluids are disappearing. Filmed the knock
https://youtu.be/JwqPox1euWQ

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Old April 12th, 2018, 09:20
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Re: How much knock is too much knock?

Sounds like a lifter. It can go a long, long time that way before failure.

I'd ignore it until it blows. Which may be another 100K miles.
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Old April 12th, 2018, 09:44
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Re: How much knock is too much knock?

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Originally Posted by cal View Post
Sounds like a lifter. It can go a long, long time that way before failure.

I'd ignore it until it blows. Which may be another 100K miles.
How will I know when it goes? How will the engine run as result

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Old April 12th, 2018, 09:47
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Re: How much knock is too much knock?

It would get a lot louder and the engine would start missing.

Or a valve would stick open, a piston would hit it and possibly blow a hole in the side of the block.
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Old April 12th, 2018, 09:49
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Re: How much knock is too much knock?

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Originally Posted by cal View Post
It would get a lot louder and the engine would start missing.

Or a valve would stick open, a piston would hit it and possibly blow a hole in the side of the block.
Okay I was curious because this engine pings and I've had to use premium only since i cant figure out what the problem is. I can see they aren't related now

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Old April 12th, 2018, 10:03
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Re: How much knock is too much knock?

Pinging is generally a problem with it being lean. Have you checked the fuel pressure?
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Old April 12th, 2018, 11:34
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Re: How much knock is too much knock?

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Pinging is generally a problem with it being lean. Have you checked the fuel pressure?
I did however I used a rental tool so not sure if it was accurate or not. I had a thread on my fuel trims a while back but I didn't get much out of it aside from go research fuel trims. Haven't had the time

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