The 7.3 Diesel has a High Pressure Oil pump (HPOP), that generates up to 3000psi engine oil, to help fire the fuel injectors. This little guy is a very precision piece that requires clean oil to function properly. Every time I do an oil change on my 7.3, it just seems to run better, which probably has to do with fresh oil circulating in the injector and HPOP loop.
Watching Bil Hewitt's youtube channel about a 'complete' oil change on the 7.3, he points out that the HPOP shares oil with the rest of the engine 'over time', but really needs to have is reservoir oil changed at regular intervals, ideally every 5000 miles along with the crankcase oil and filter.
There's a small plug, and you need a pump to suck the old oil out. Hmmm... who knew? It's a pain to get at in the van, but I figured I'd tackle it Saturday morning, it should take me 2hrs tops, right?
I decide to use the cheap little plastic pump that I have for pump gear lube into differentials and transfer cases.
It starts to mist, then sprinkle, then rain...
That's when the straw fell off the pump, disappearing into the depths of oil reservoir
My day went from 'not bad' to awful in a instant.
I took all the bolts out to loosen the cover, the high pressure sensor and steel fitting that's all but impossible to get at, and only after taking out the interior engine cover. At least I'm out of the rain, if only for a moment. Instead of the HPOP oil reservoir top cover coming loose when I prying on it, the entire reservoir came loose from the timing cover, disturbing the base seal and puking a quart of oil onto my serpentine belt and down the front of the engine.
Luckily the Ford dealer had the base seal/gasket in stock (which had been leaking down the front of the engine, anyhow). I rent the serpentine belt tensioner tool from O'Riely's. Brand new in the case, too, which broke at the weld with my gentile use. Must have been a brittle weld.
At this point, I changed my mindset from 'quick oil change' to 'In for a nickle, in for a dollar' mindset.
I decide to change the now semi-exposed fuel bowl filter. I re-tap two turns deeper, one of the the steel high pressure fittings, which had been leaking a at the sender, while I was at it. I taped up a section of wiring harness, where the plastic covering had gotten brittle with time. I found the steel bracket that holds the cast aluminum resonator, was broken, allowing the resonator to flop around an rattle. Yep, I removed it and welded it back together with a stiffener. and welded the rented tool back together, hitting both with satin black rattle can paint. I re-sealed the breather box, that's on top of the driver's side valve cover, with new o-rings, while I was at it. The 'wisp of escaping vapor', was now gone.
10 hours and a sore back later, the oil was changed, I have 3 fewer minor oil leaks, one less rattle (it's a 7.3, I'll never notice), and fresh, clean oil in the HPOP reservoir