Jesse Ransom
Jesse Ransom GRM+ Memberand MegaDork
10/18/24 8:42 p.m.

This is a stupid question. When you get to the point where you wonder why I'm asking such a stupid question, at least recall that I'm already aware, I just can't stop myself asking. The truck search drags on and I'm frustrated and want something to work out.

I'm truck shopping, and looking currently at an '08 F-350. I can't get to it in person, but the owner has kindly agreed to take it to a shop I found near him for a PPI, which will happen next week if I don't call it off over this item.

He also provided me with some diagnostics the truck got when he had some work done (replacing thermostats) in May, and there's some concerning stuff in the text of that testing. I'm hoping folks here with more Diesel-Fu than me can tell me whether it's a "that's not concerning," "that is concerning," or "run screaming." It feels like a "run screaming" and I may well go with that. I think maybe I've got false hope just because of the way it's added to the text almost in passing. And the fact the seller was happy to provide me with the docs from the shop. Maybe I'm taking crazy pills, but is there a non-horrifying explanation? As I type them up, I feel silly for even asking. I think maybe this is a prime example of how people end up doing crazy things if everyone around them seems sane and keeps up the appearance of normalcy...

Specifically, two things:

  1. "Checked crankcase pressure and found out of the oil fill it is pulsing indicating a compromised cylinder causing the excess pressure. It is normal to have some excess pressure in the crankcase but it should not pulse."
  2. "Also checked short term fuel trims for the injectors and found cylinder 8 was the highest reading a max of 7 but was fluctuating. Suspect base engine concern failed piston rings or piston itself is in the early stages of failing."

Is there anything else that stuff could be? Or any reason not to assume the obvious and unpleasant? See my Minor Rant about the scarcity of Supercab/long bed trucks to know why I'm so desperate.

ShawnG
ShawnG MegaDork
10/18/24 10:03 p.m.

Run away.

You have a cylinder that's failing.

Unless you want to buy a truck that you're going to need to replace the engine in short order.

Steve_Jones
Steve_Jones UltraDork
10/18/24 10:15 p.m.

On a diesel, excessive crankcase pressure is caused by 1 of 3 things.  The EGR system, Bad turbocharger oil seals, or excess leakage past the piston rings. With #2 above, it's pretty much a given it's a bad cylinder. This is not the one to buy. 

Jesse Ransom
Jesse Ransom GRM+ Memberand MegaDork
10/18/24 10:20 p.m.

Thanks for helping me face the simple truth.

Nice to be able to walk away with confirmation.

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