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Discussion Starter · #1 ·
Guys, you may have read my thread about my engine knock. I thought I would pull off the belt just now to see if it changed anything and I think it did. I only hear this knock after the engine warms up, so I started the Jeep and let it idle for about 15 minutes and the knock started.

What would be the most "likely" cause of the belt driven components to make a knocking sound? I thought water pump, but my experience is they make a different sound. The knock I hear will increase with RPMs until about 2,500 or so. It either then disappears, or it blends in with the other engine noises and I can't hear it.

I'm thinking I might change the water pump anyway because I saw one little wet spot on the engine beside the pump.

I would appreciate your thoughts. Thanks.
 

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It ran for 15 minutes with no belt on it and didn't get hot? Have you tried a stethoscope or use a long pry bar and touch it to various parts while listening through it and see if you can pin point the source? Hopefully you will hear where it is coming from a little better.
 

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Discussion Starter · #3 ·
It ran for 15 minutes with no belt on it and didn't get hot? Have you tried a stethoscope or use a long pry bar and touch it to various parts while listening through it and see if you can pin point the source? Hopefully you will hear where it is coming from a little better.
I'm sorry, I wasn't clear, was I? I meant that I started the Jeep until it warmed up, and then I could hear the noise. I removed the belt, AFTER the engine was warmed and the noise stopped. Sorry! :blackeye

I also used a stethoscope to listen around and I do most definitely hear the knocking when I touch the water pump. When the belt is off, no noise. I did not think water pump would knock when they're going bad, that is why I posed this question. I expected a grinding noise of sorts. 35,000 miles seems early for a water pump to go out, but who knows. If it turns out to be the pump, then I will be one happy camper. I've been reading WAY too many posts about bearings, lifters, pistons, etc.

You have any other suggestions? Otherwise, I'm gonna do the pump swap in the morning. Thanks for the reply!
 

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Yes it was a little confusing the first time. Makes sense now though, I would guess water pump if it stopped when belt off and you heard it there. A bearing in a pulley can make a knocking noise though. My best guess, not a mechanic, but can do a little work under a shade tree, lol. Maybe a little more experienced person will see this.
 

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Discussion Starter · #5 ·
That's me too, Steve. Shade tree all day! The only place I could really put the scope was to the left of the water pump pulley. I heard the knock in that location. It is right next to the belt tensioner, so I also thought that might be it too.
 

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Discussion Starter · #6 ·
Replaced the water pump and that wasn't it! Not complaining, the old pump had a slow weep. Only $40 for the part. However, while the pump was being replaced, I noticed the power steering pump makes a nice little knock sound when you wiggle the pulley. I think I have found the issue. I know what I'm doing on my next day off!
 

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If the water pump pulley is wiggleing, I wouldn't wait too long to replace it. While you're at it, might as well replace the tensioner as well.
 

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Discussion Starter · #8 ·
If the water pump pulley is wiggleing, I wouldn't wait too long to replace it. While you're at it, might as well replace the tensioner as well.
Yes, I already swapped the water pump. The power steering pump is next to do, probably Wednesday. The tensioner I will check after the PS pump. If it isn't knocking, I can't see spending the $80 they want for one.
 
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