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Discussion Starter #1
How does this typically happen? My latest oil analysis came back. 5k sample. Went from <1% to 2.1. It states excessive idling as possible cause.

The last sample was taken January 2019. Truck warms up twice a day allowing the thermostat to open. In the mornings, I start it up and watch my mechanical oil pressure gauge go to about 70-80 PSI. Once it’s steady, I head out. Not much idle time. Maybe a minute?

I did deploy this summer. Truck sat from mid May to the end of September. I’m in NC with hot and humid summers.

The ONLY time I idled was in January of last year. I sat for about 3 hours with it running. Would that make up that change?

Thanks.


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Which PDD injectors are you running? My fuel dilution is up a hair too at 1.5 and I don’t idle either.
 

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Discussion Starter #3
Their budget 5x.012. Had them since 2016. Got about 30k on them.


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The Uppity 12v Guy
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The only legit (meaning lab-corroborated) instances I've seen of fuel dilution to that degree in 12v trucks were associated with weak injection pumps. Fuel leaking through the plungers was the presumption.

I might be inclined to believe extended idle time in cold weather with massive injectors (5x18 and up) could cause fuel dilution, but not a 5x12.
 

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Wouldn't the bigger concern with that scenario be cylinder wash? I'm not sure.
 

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Well that doesn’t sound good. If the pump were the issue, would there be any other signs? Rough idle, stumble, etc.

Since I rebuilt it, I’ve never noticed a change in sound or anything. Sounds very strong the throttle response is excellent.

The only driving habit change has been with loss of 5th gear. Because of that, I spend more time around 2000-2250k RPM. But that’s nothing for these engines. Fuel mileage has been a consistent 16 MPG since I lost 5th.


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Wouldn't the bigger concern with that scenario be cylinder wash? I'm not sure.

I’d rather that. I can inexpensively fix that. But I can’t see it only because my EGTs are ALWAYS above 400* (pre turbo) unless idling. They may have lowered slightly since losing 5th gear at cruising (60 MPH) speeds, but nothing that would make me assume I glazed over the cylinders.

Unless leaky injector for 4 plus months, then start up??


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The Uppity 12v Guy
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Wouldn't the bigger concern with that scenario be cylinder wash? I'm not sure.
Eh, kind of. For the most part, what modern diesel guys claim as "cylinder wash" is a mostly esoteric, non-specific diagnosis for "something happened to my piston rings" of which the root cause is most often overlooked or misinterpreted, either due to a lack of knowledge of the owner or the dealer trying to obfuscate the issue to Dodge a warranty claim. We don't need to go down that specific rabbit hole as it's not really relevant to 12vs, but in short, it's almost impossible to actually wreck a 12v by cylinder washing it. A lot of people seem to think it happens immediately every time the truck idles below freezing. I can come up with a set of circumstances where it might occur, but nobody in North Carolina needs to worry about it. Dudes idling their trucks for days on end in the frozen wasteland of northern Alberta need to worry about it. In situations where it can occur, it's bitter cold to the point the engine can't generate enough heat at idle to maintain operating temp. While fuel may not be burning, and may be pooling in the bowl, and may be splashing on the walls, and would then be making it's way past the rings and into the crankcase, it's been known for a long time that ring wear rates increase dramatically the farther the engine is from operating temp. I've seen nothing scientific to support the idea that the presence of liquid fuel in/around the rings is actually causing physical damage to the rings or walls.

Until that claim is backed up with legit data, it's an old wives tale as far as I'm concerned.

Well that doesn’t sound good. If the pump were the issue, would there be any other signs? Rough idle, stumble, etc.

Since I rebuilt it, I’ve never noticed a change in sound or anything. Sounds very strong the throttle response is excellent.

The only driving habit change has been with loss of 5th gear. Because of that, I spend more time around 2000-2250k RPM. But that’s nothing for these engines. Fuel mileage has been a consistent 16 MPG since I lost 5th.
I doubt you'd notice anything. It would be a very slow wear process. Is the pump original or has it been worked on?
 

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Discussion Starter #9
I doubt you'd notice anything. It would be a very slow wear process. Is the pump original or has it been worked on?

It is not. Replaced. My 215 crapped itself (leaky seals) and I got this 180 now. Had it since the rebuild. 30k or so. Got it from some one on here.



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The Uppity 12v Guy
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It could have been a leaky injector allowing a pooling effect over time. Did it start up with tons of abnormal smoke when you got back?

To put it in perspective, 2% fuel dilution works out to about one cup (as in baking) of fuel in the sump. This is about 225 mL or about 4,550 drops. There are 2,880 hours in a 4-month time period. That would work out to 1.6 drops per hour or about one drop every 38 minutes. Yes, this assumes all the fuel went into the oil, but that isn't a hard leakage rate to imagine.
 

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Discussion Starter #11
It could have been a leaky injector allowing a pooling effect over time. Did it start up with tons of abnormal smoke when you got back?



To put it in perspective, 2% fuel dilution works out to about one cup (as in baking) of fuel in the sump. This is about 225 mL or about 4,550 drops. There are 2,880 hours in a 4-month time period. That would work out to 1.6 drops per hour or about one drop every 38 minutes. Yes, this assumes all the fuel went into the oil, but that isn't a hard leakage rate to imagine.

It need to be jumped, but it fired right up. I didn’t see any abnormal smoke, but I also didn’t look at my tailpipe.


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The Uppity 12v Guy
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If you had a piston bowl full of fuel there would have been tons of smoke and it probably would have been knocking a little due to the ultra-high compression.
 

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I've heard of the lift pump leaking fuel into the oil pan in the past. I don't know if it was fact or conjecture.
 

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The Uppity 12v Guy
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Excellent point, Gary, you are correct.

There is a weep hole in the pump body between the shaft seal and where the shaft enters the crankcase, but it wouldn't take much in the way of engine grime or dirt buildup to block it partially or completely.
 

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Discussion Starter #17
Too high fuel pressure? Blew a seal in the IP?


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The Uppity 12v Guy
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No, the lift pump. There's no leakage path between the injection pump gallery and the crankcase. The only seals in the IP that can fail from high supply pressure are the DV holder seals (normally green o-rings).
 

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Discussion Starter #19
So your first post about fuel leaking past the plungers would result in the fuel getting into the oil from where? I don’t fully understand the ins and outs of the high pressure side of our fuel system. If it’s not internally in the pump, then it would have to be through the injectors, right? So wouldn’t that in turn mean I also have a leaking injector?


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The Uppity 12v Guy
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The only potential leakage path that exists between the injection pump and the crankcase are the barrels/plungers themselves. There is no mechanical seal, the sealing between the high-pressure side of the elements and the IP sump (directly connected to the engine crankcase) is achieved by very tight clearances between the plunger and barrel (on the order of 2-4 microns, or .0000787 to .0001575 inches). This clearance is sufficiently tight that the mere surface tension of the fuel is enough to keep the fuel from "flowing" from the high-pressure section of the injection units to the IP sump. There is a special drain notch near the bottom of the plunger which lines up with a weep hole near the bottom of the barrel to give any leaked fuel a path of no resistance back to the fuel gallery. Gallery pressure is present there all the time, but the 30-60 psi of your gallery pressure is nothing compared to the 18,000+ psi that this interface can handle during injection.

I've seen new Chinese plungers pass fuel into the crankcase, because they can't hit the factory clearances (so they run them on the loose side), but worn factory barrels/plungers can do this as well. This is a long-term wear thing though, if your fuel dilution thing started out of the blue all at once, this isn't what's going on. Either you had a slow injector seep that daily/weekly running was correcting and you've just now observed it after the truck sat (it had enough time to fill up the piston bowl and overflow into the crankcase before the engine running burned it off) or it's getting in through your mechanical lift pump. Based on your description of how it ran on startup, I'm thinking the LP is the likely culprit.
 
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