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Harsh knocking noise from back of engine or front of transmission...

sharonis3

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On my 2002 4.6 - 141,000 miles I have a really harsh metallic tapping coming from the back of the engine..... at idle and fades as RPM increase.... seemed to come from the drivers side, rear top of engine....

I popped the valve cover off and had a bad timing chain ( had eaten thru the guide and chain was eating thru the tensioner piston) Did not think this was making the noise - but had to replace all parts on both sides....as it was ready to grenade...

I thought the knocking/tapping might be a lifter- so while I was in there doing the chains - I put a set of OEM Ford lifters on the whole drivers side head....so 8 lifters....

Still had knock....

Now I just noticed - if I put step on the brake and apply throttle the knocking stops..... so is this a flex plate cracked or loose.... or a torque converter issue.... or engine knock... what metallic knock would disappear when you put the drive train under load.....?

Noise seems more on drivers side, maybe this is coming from the front of the transmission and tricked me into believing it was a head issue.....
 


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kydirtscooter

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Without hearing the noise it is difficult to say. There was a run of 02/03 4.6s that had noisy torque converters which usualy made a metallic clicking/tapping noise at idle and up through 2,500 or so rpm. A locked torque converter made the noise stop. Ford's response was it did not affect durability just annoying.

A similar noise with roughly the same characteristics is the drivers side converter matrix failing and a loose chunk exhibiting more of a rattling noise.

Two things, what is the maintenance history and can you get a video of the noise?
 




kydirtscooter

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Run it up to 40mph with OD off. Flat ground, light throttle pressure. Increase throttle application enough to accelerate but not downshift. Is the noise quiet?
 




974X4BLACKSPORT

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Chances are it's either the flex-plate, or something in the tq. converter. You can unbolt the converter from the flex-plate, slide the converter back to clear the flex-plate, then with your hand try to wiggle the flex-plate and see if it makes noise, or give the flex-plate a tap with a hammer and listen for a good ring, if it make a thud sound when tapped with the hammer, then you definitely have a broken flex-plate.
 




sharonis3

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Hi: Going to tackle it this weekend....Take a look at video - shows noise from engine, wheel wheels and under truck.
https://youtu.be/SAF88ECZzlg

Things I will check....
1) If at 40 mph and overdrive off... no noise during lite acceleration - does that mean it is the TC issue....
2) I might pop off the drivers side valve cover and make sure the oil restrictor is not partially plugged up and starving the lifters of oil..
3) Flex plate check - Great suggestion 974x4BlackSport - I did not know that I could check the flex-plate in place like this, without dropping the transmission...

Thinking it might be a plugged oil Restrictor on the drivers side......

Let me know what you think....
 




sharonis3

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Popped the valve cover off...and then front cam cover where the oil feed and restrictor is....It does not have the pushed in tube restrictor with two holes....mine has a chamber with 2 sections - with a rectangular notch cut out... so this must be the restrictor.....anyway it looks clear....See the first photo second cam bearing is rough, drag your fingernail across it and it drags hard....

Tomorrow:
1) Will try taking the rocker arms off one cylinder at a time... and run the engine - see if the noise disappears.....rule out lifters, rocker arms and valve/valve guides... Also make sure the rocker arm roller bearing is okay....
2) Watch to see how much oil is in this head when engine is running, with everything together, except valve cover.
3) would like to take off the front cam cover/restrictor chamber and just crank the engine and see how much oil comes out....think this is okay.... cam chain would hold down the front of the cam and the rear half cam bearing support would still be there.....

Comments......

5A36DEDB-89D6-4942-A150-29205AB51062.jpeg


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C31D0FDE-7EBD-408B-B0A2-B491849944FF.jpeg
 




sharonis3

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Today - put the front Cam tower cover back on...then started up to check for oil at all lifters... all looked good and all lifters were pumped up.Ran her with the two lifters out on the rear cylinder....Lots of oil...So definitely not an oil restriction issue. Cut the bottom out of a gallon windshield jug....and held it in place with gasket sealant and 2 valve cover bolts... Great way to be keep the cam chain from throwing oil everywhere....

Pulled the rocker arms all out and they were all good..had to bled the lifters down, before I could get the rocker arms back on, so that means the lifters were all good...

So nothing looked like it was going to blowup in the drivers side head......Will box it back up.....

Now to figure out what is making that tapping noise....

Take a look at the video and let me know what you think it is....
 




Joe in NY

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wishing you luck on finding the noise!

Strangely, this is the exact same noise my brothers Subaru 3.0 H6 motor was making after we replaced the head gaskets and had the heads rebuilt. Ran great but the exact same noise.. So definitely something to do with the top end..
 




rtk11

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Good luck finding the noise. I had a knocking noise I thought was transmission which I just had rebuilt. After a lot of searching and replacing of parts (including the full exhaust system with catalytic converters) and checking top end for noise, my Explorer turned out to have rod knock which I solved with a rebuilt engine. Hopefully yours doesn’t turn out to be that involved, and hopefully is an easy (or easier) fix.
 




974X4BLACKSPORT

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A mechanics stethoscope can help you better locate the where the noise is coming from, follow the sound to the source as best as possible.
The sound to me appears to be at half crank shaft speed, which can point to valvetrain noise, a worn valve guide, loose or dropped valve seat, broken valve spring.
Is there visible metal flake in the engine oil?
 




boominXplorer

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Make sure the oil rail isn't hitting the cam lobe. It's common after a sloppy valve cover gasket job. All it takes is a little lean on it with the palm of your hand and it will bend.
 




sharonis3

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Here is her running with the valve cover off..... about 30 seconds into video - goes off fast idle and the slower engine speed makes the tap clearer....


Been tapping for about 12,000 miles.....

Keith
 




974X4BLACKSPORT

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Hook a vacuum gauge to full manifold vacuum at idle and watch the needle. The needle should be steady, it;s not the actual reading we are looking for, it's movement of the needle, any movement of the needle on the gauge could indicate an intake valve seat failure. I just suggest this because it is very easy to do.
 




boominXplorer

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So I'm a dummy, my earlier response was for a v6 engine.

Your tap does seem like it's in that head. Lay underneath the truck, is it any louder? Revving it up to 1200 rpms doubles the oil pressure from idle. I've seen timing chain debris get all up in the lash adjuster oil feed, but with you swapping them all out kinda rules that out. Check all valve springs to make sure none are broken.
 




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