03 navigator loud knocking noise from rear of engine at low rpms.

[Andy J]

Hey guys,

You.might recall a few months ago i did a complete tear.down and rebuild on my 03 navigator 5.4 32v.
It had been running great until last night. I was on my way home from work and i stopped at a light and noticed a loud knocking coming from under the truck. I finished my drive home, and when i got.home, i crawled under the truck. The noise sounds like its coming from the upper bell housing area and when you get near the passenger side, its very loud. The noise only happens up.to about 1500 rpms, and the. It goes away. The engine is running perfectly smoothe and it drives great too. The engine has good oil pressure and is newly built so in pretty sure its not the engine.

The truck does have the 4r100 trans and from what i have been reading, the flexplates and converters in the diesels with 4r100 can cause issues. I pulled the inspection cover for the trans, but didnt see.anything wrong.

What are your thoughts.

Thanks,
Andy

 

[Andy J]

Heres a video.

 

[1955moose]

Sure sounds like it. If it were a bottom end bearing, it would as you already know, get worse with rpm. Top end would be more tickey as a rule. Looks like your pulling the tranny! And you thought it was a slam dunk! Surprise, its always something.

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[Andy J]

Lol i know. I was happy with the fact that i had gotten everything fixed except the seat heaters/coolers. That was my last remaining issue. I even rewarded the truck with a full sound system. Im just hoping its the flexplate, but i am probably going to buy a new converter also. I dunno lol.

 

[Andy J]

Any recommendations on a converter yall have used? The only converters i have bought have been fully built ones for ford diesels and my silverado back in the day. I dont need a fully built one, just one a bit better then stock, possibly furnace brazed.

 

[Ed_Strong]

So sorry to hear that buddy...
To me sounds like solid metal. It could be the flex plate or also the flywheel.
I really hope it an easy fix!

 

[1955moose]

Their expensive buggers. On the cheaper end $230.00 on up, Ford ones run like almost $500.00 for new ones. What about finding a reputable place that can rebuild yours? Your truck may be down for a week but its gotta be better than buying a made in China one, or going $450.00 to $500.00 Most torque convertors go the life of vehicle, but these sometimes act up, and cause that rumble strip feeling. Well that's what I'd consider at least.

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[Andy J]

Thanks guys. Today is my only day off so i better get crackin on this. Im going to try and have it done asap, so i dont have to keep driving my diesel. Id love to pull the trans and run the engine to make sure it was ok, but i dont know if its possible. Id have to jump out the neutral safety switch among other things.

 

[1955moose]

You should be able to. It's no different than running one on a dyno by itself. Just don't rev it too hard so you don't stress the motor mounts. It should be pretty obvious if the plate is cracked, or something is wrong with flywheel. If something's been scraping, you'll see the wear marks.

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[Andy J]

Im praying that its just a cracked flexplate or.bad converter. I.ordered both. Should be here on monday.