Guess what's knocking? <<VIDEO>>
 

This is a friend's 1998 T/A which developed a knock on the commute to work. He had already been driving for ~50 miles and was sitting in morning traffic with good oil pressure when it started. He immediately pulled over and checked the oil level and everything was fine. He drove the last 5-10 miles into work and parked it, but we're trying to guess the source of the knock. It idles and drives smooth still according to the owner.

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It started out as kind of a rattling sound on the day it started, and sounds louder on the passenger side. I already pulled the passenger side valve cover and checked the springs/rockers/pushrods but they're all fine. After putting it all back together and starting it cold, it's definitely a pronounced knock.

Any takers?

Oh yeah, my guess is a wrist pin. :D

:eek2: That sounds terrible...

How many miles on the motor?

knock
 

is that knock definatly inside the motor?

I'm guessing lifter, not wrist pin.

I know you said you checked under the valve cover, but it sure sounds like a lifter to me. Pull the head off and look. How many miles on the motor??

sounds like a lifter but i would like to have heard it reved up. does it get quiet when you you back off the throtle?

sounds like a lifter to me. have you pulled the oil filter and cut it open to check for any metal? it sounds too p to be anything in the bottom end, but then again it's hard to tell from a video. almost sounds like something hitting plastic, like a pulley or something...that's odd.

Hey guys, the car is a 1998 with 83k miles on it and is 100% stock except for a lid, FTRA, and trans. and VE tuning with HPT.

The knock actually started out as a rattle which we both thought was coming from the passenger side head. After taking it apart and putting it back together, I started it back up and now it sounds more like a deeper pitched knock coming from farther down in the block. The video sounds more like a tapping sound than a knock, so I hope that's not throwing anybody off with their diagnosis. It isn't a real accurate representation of the sound. :(

The owner just told me that the sound gets faster and slower in relation to engine RPM but doesn't really change in tone. This was during the final few miles into work.

I haven't pulled the oil filter yet but will try to do that this afternoon or tomorrow.

Vodas00SS, it does sound like it's coming from inside the engine to me but someone else suggested that it might even be broken pieces of a cat rattling around inside the housing.

Hi Folks
It sounds like a lifter or a valve to me but I do a very simple test, remove the serp. belt and try running the car. You will not have a water pump, so don't run to long, just enough to heard the engine. I don't believe it is an accessory but just remove that as an unknown.
Bill :usa:

I think a rocker arm has come loose or come apart and it's slappin around in there. Pull the valvecovers and check the rockers ASAP...

:devil:

:bang:

Man that sounds just like my car when a Lifter went bad ! EXACTLY ! Have you turned the motor over and checked for a loose rocker ?( I know you said you checked them , but what I mean is turning the motor over and checking at different points of rocker travel ) When I did I found a very loose rocker , took it apart , but the rocker and pushrod were ok . Found out it was the lifter that had come apart in the motor . There was no slack in the rocker when it was opening the valve , just when it was closed . Hope this post helps . . .

Yes...that was my next guess...I don't think it's piston related. It's valvetrain somewhere...

im gonna guess lifter

thats the same sound when my 1996 exploder had a lifter problem

I'm going to pull the VC back off after work and see if I can find a dead lifter by rotating the engine. Is there anything else I need to check while it's off? Any other way to check the lifters?

check the lash on the valves if any have lash, with a hydraulic cam, yu've probably found your bad lifter. listening to the speed of the tick makes me agree with everyone that says its valvetrain related

Sounds like collapsed lifter. Or turned lifter.

Could have also flatend out a lobe on your cam.