Engine "knocking" sound???

WJCO

Meme King
Sounds like an exhaust leak but also sounds like a knocking noise. Sorry, man. The sooner you deal with it the better. If it's just a rod knock, a new set of bearings may fix it as long as the crankshaft isn't scored. I assume you have a 3.8? Not uncommon for rod bearings to fail.
 
Sounds like rod knock, but it can be several other things as-well including the fuel and exaust. What type of Oil are u running and what grade of fuel? Have u changed the spark plugs or wires?
 

clark98ut

New member
Engine "knocking" sound???

Correct on it being a 3.8. 2007 with 86k-ish miles. It doesn't sound like an exhaust leak, but you can hear the sound out the exhaust.

I haven't changed plugs or wires. Picked this up about 3 months ago. 5W20 on the oil.
 
Yea most likely i'm going to bet my cards on it is rod knock and i would get that checked ASAP and hopefully as mentioned before it didn't score the crankshaft but it's hard to know till it get's inspected.
 

fiend

Caught the Bug
It does not sound like exhaust to me. It is irregular. Have you checked simple and benign things like loose bolts, heat shields, etc. ?


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clark98ut

New member
It does not sound like exhaust to me. It is irregular. Have you checked simple and benign things like loose bolts, heat shields, etc. ?


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I haven't checked anything really. But I agree with you about it sounding like something is loose. I'll poke around. Any places I should start the search?


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Well i would recommend u to a shop near me but u live in Texas and i live in Cali i would search local shops around your area and places that have been in the business for 10+ years and know what they are doing. If u can't find a decent shop i would take it to the dealer but be midnful they will charge quite a bit unless your rig is under warranty.
 

clark98ut

New member
Ok, so this noise seems to come and go, but it's been back pretty steady lately. Today I removed the serpentine belt and the noise went away. Does that make any sense? None of the pulleys feel loose.


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WJCO

Meme King
Carefully use apiece of hose as a stethoscope. I bet you'll find it quickly. You can even get a stethoscope at the auto parts store.
 

Bierpower

Hooked
Did you spin all of the idlers by hand to see if they make noise? They will be ten fold louder with the engine running. Also your water pump should have no play.

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clark98ut

New member
Everything spun fine. Nothing wrong there. The play in the water pump is very minimal, but that could be what's causing the sound.


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jknikos

Member
If its the water pump its an easy fix and you are lucky! How many miles? I have the same engine with 125000 miles and have never changed a water pump.
 

clark98ut

New member
I wanted to update this thread in case anyone else has the same problem.

It was the water pump making that noise. Replaced the pump and the sound is gone.

When I had the old pump out, if you spun it really fast, you could hear the knock sound. The bearings felt a little gritty. I'm guessing there's a piece of something in there that would cause that bearing to jump ever so slightly and cause that knock sound.


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