Hey guys - could use your help in case any of you have run across this before, sorry for the novel-length post!
I took my rig for a trip from Portland to Boise and back a few weeks ago, truck was running awesome. Spent most of the highway miles between 75-80MPH, a little over 3000 RPM.
- When I got back to Portland, I noticed that a rattle has developed. Also, my oil was much grayer than it should have been.
- The rattle is rhythmic, sounds to be 2x the speed a cylinder would see spark. I have a little pressure gauge on my fuel line that pulses with the fuel pump, seems to be going the same speed as the fuel pulses. Fuel pressure centers around 5psi.
- Drained the oil, magnetic plug had a nice little mushroom of filings on it
- Took apart my oil filter (it's one of those reusable ones), and had a bunch of metal on the internal magnet.
- Had a bunch of shavings that didn't make it through the filter element as well but didn't stick to the magnet (maybe there was too much stuff already there?)
- Pulled valve covers, measured lobe lift - checked out A-OK (within 0.002 for all but the exhaust on #1, which was 0.008)
- Pulled intake to see what's what, had on slightly dished lifter on #1 (barely). I also noticed that I had no preload on most of the lifters.
- Pulled rocker arms, some were extremely worn. Replaced rockers & got preload when installing.
- Pushrods are correct length and not worn.
- Oil pressure is awesome - 50psi warm in idle, 70psi @ 2000RPM.
- Dizzy gear shows normal wear patterns (not much at all).
- Still have plenty of power.
Couldn't see any obvious culprit for the metal shavings, so stitched it all back together & fired her up. Still have the rattle.
Then did what I should have done in the 1st place, and listened with a stethoscope (with the contact wand). Rattle is not coming from the valve covers, intake or the block by the plugs.
It is super loud on the dizzy clamp, and also fuel pump.
Tried to take a video so you can hear it, but all my phone picks up is wind from the fan.
What could be the culprit? Could it be the fuel pump? Would that explain the shavings?
I can start pulling stuff apart blindly, but if you guys have advice on what to look at 1st am all ears.
Thanks for your time!