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Discussion Starter · #1 ·
I will start with some history on the vehicle. I am the technician working on it.

2008 f250 6.4 with 80,000 miles. Lift kit, DPF delete, unknown tune

Comes in, WIF light on, replaced both fuel filters and reset WIF light with IDS. Found some gunk in the lower filter housing, cleaned the best I could given the time allotted.

Customer continues to come in for normal maintenance.

Comes in complaining of a vibration. I immediately think it is driveline related based on the lift and tires and previous recommendations for suspension work. When test driving I feel no driveline vibration, and feel what seems like a slight misfire. Can feel it in park when RPMs are raised to around 12-1500.

Use IDS, retrieve code for ICP pressure too low. Run power balance test and see Cylinder 6 dropping on graph during vibration. Run relative compression test and cyl 6 showing 6% lower than all others, and cyl 4 also showing a slight drop at 3%. I test drive again and monitor FRP and don't see anything too wacky. I notice when I got back from test drive that coolant had spewed out of the degas cap. I did not notice anything wrong with temperatures, so I top off coolant, drive again, I notice the EOT is a little higher than ECT, but not over 205. Cant get coolant to spew again. Ordered a new degas cap. Removed valve covers to inspect rocker arms and push rods and don't find anything. OHM injectors and harness and don't find anything. Removed 6 injector and noticed line had very metallic diesel coming out. Drain fuel from lower housing and find what looks like rust and other debris. Now Im thinking the HPFP was starved and worn and has caused injector problems. I also forgot to mention that the STFT for cyl 1 was at positive 18 and minus 6-8 for cyl 6. I pressure test cooling system overnight and boroscope cyl 6 for coolant in the cylinder and find nothing.

I don't have a compression tester to test manual compression and getting hounded by extended warranty for an answer..

I ordered a compression tester but it will be a week before it arrives..

anyone seen this issue???

· Registered
212 Posts
that HPFP is toast... and, it grenading sent shavings throughout the fuel systems, which is a good way to crash injectors...

WIF light is about useless- by the time you see it, it's too late... It's precisely like identifying a biological weapon exposure after you've been exposed.. at least you know what got you..

"water in fuel is about the worst thing you can do- the HPFP pushes it at ridiculous pressures, but it also uses the stuff to cool and lubricate the thing... water will destroy it with a quickness, which is why I put an aftermarket low pressure pump on my rig before I had even put 100 miles on it- extra filtration, extra water separating capacity, extra volume of flow- volume of flow, because the only thing by my reckoning worse than wet fuel is running the hpfp dry.... now THAT will whack it quick-like."​

the degas spewing is likely stretched head bolts, floating the heads during high pressure events, which will result in destroyed gaskets given enough time. they're already damaged, let there be little doubt, but may be sealing when the heads come back down... there aren't that many ways to puke the degas- head gaskets, ruptured EGR cooler, or just a bad degas cap (which happens all the time; $5 fixes rock, no?)...

the cylinders sound like they have been abused, either starved for fuel or more likely over fueled due to hanging injectors, hanging injectors because of debris, debris due to grenaded HPFP... I bet a tear down would reveal rings that have been worked over at the very least.
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