Hi, I have a 2000 ford expedition, eddie bauer edition with the 4x4 package. It has 124k miles and has a 5.4 liter v8 2v and a 4r100 gasoline transmission. Both the engine and transmission are original and run fine, especially the transmission. I managed to get 21 mpg from the engine once.
There is this knock sound from the engine that isn't really loud and sound like hitting solid metal. It has been making this sound for years and thousands of miles and it isn't really louder. The sound gets very quiet almost inaudible after the engine has been running for and hour or so. I couldn't trace the sound to an exact location with a mechanic stethoscope but it was loudest on the passenger side when I put the stethoscope on the exhaust manifold, it was impossible by ear because it sounds like it's coming from everywhere so I had to use the stethoscope. The knock increases with rpm but you can't hear it above 1500 rpm . The engine has good oil pressure and outputs good power for the age. I have noticed the engine feels slightly less powerful for a few min after a cold start, and than it gets a little quieter and can't here it anymore at higher rpm's only at idle.. . I have kept up on maintenance but it never needs any apart from oil changes.
An exhaust manifold leak (cracked manifold, bad gasket, missing bolt) can sound like an engine knock. Another possibility would be loose bolts on the transmission flex plate.
Upon further inspection of the passenger exhaust manifold, I found one of the rear most bolts was broken, which these engines are notorious for
That may be the source of the noise. You could try verifying it with a mechanic's stethoscope if there's enough room to get in there with one.
When you replace it be sure to use stainless studs/nuts or you'll have it happen again sooner than later.
Ford REALLY let the bean counters have at it in the anti-corrosion department since the mid 90s. From body to frame to manifolds, one whiff of winter & they give up the ghost.
It sucks because other than the quality control going out the window those trucks are nice to drive.
Once they make it to the age where emissions/inspections are no longer required, prime candidates for a 351w or sbc swap mated to a stout non-compooper tranny with a gear vendors overdrive unit.
The noise is loudest at the passenger manifold, I have a longing stethoscope, but not where the broken stud is
I would be interested in knowing what weight oil you are using. Is it that which is recommended by the manufacturer for the ambient temperature you're operating in?
I'm using 5w20 and I'm in Washington so the temp is anywhere from 18 degree to 100
My question was, is this the correct weight oil recommended by the manufacturer for that ambient temperature? Please check your owner's manual. Also, have you had it scanned for any codes? Thanks.
The manual says use motorcraft 5w20 which I'm using. And no I haven't scanned for codes but there are no idiot lights
Sometimes codes are present without the light being on(say if the battery died or was disconnected), you just need a decent scan tool to check the history.
Aside from that the computer allows for around a 20% margin of error so live data is something to watch when you suspect an issue but no CEL or codes show.
As you found though, those passenger manifolds love to go. Both my 99 F150 & 03 F250 with the 5.4 did this, the former got so bad is sounded like open headers.