2025 6.8 Failure
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Mountain Pass
Joined: May 2025
Posts: 181
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2025 6.8 Failure
We'll be tearing this one down soon. 2025 F250 6.8 with 46k. Came in for a check engine light concern, i guess they couldn't hear the rattle. Misfires on 1 and 5. This is borescope on cylinder 5. Unacceptable photo for prior approval as the VIN has to be included in the picture so the customer will be down for the duration of getting every little shred of evidence they(Ford) can think of. Maybe I'll pull the pan and take a peak at the crank's casting line to see if its forged or cast...
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Mountain Pass
Joined: May 2025
Posts: 181
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Yup, waiting to see if Ford wants us to tear it down or will go ahead and authorize the replacement. The last oil change was 188 miles ago so the filter was clean. I suspect we'll be tearing it down to causal
Lead Driver
Joined: Feb 2005
Posts: 7,923
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From: The Great State of Texas
What a shame...
Been noticing a pattern when a lifter fails and in that associated cylinder also has major cylinder scars. I suspect because there's little compression on that cylinder?
Been noticing a pattern when a lifter fails and in that associated cylinder also has major cylinder scars. I suspect because there's little compression on that cylinder?
Mountain Pass
Joined: Dec 2025
Posts: 104
Likes: 46
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Mountain Pass
Joined: May 2025
Posts: 181
Likes: 115
I'll check idle hours. Oil has been changed almost exclusively at the dealership. As far as the walls getting scored, I think it may be due to the oil squirters spraying the metal off the failing lobe and roller onto the cylinder wall. I won't be able to get any further details til the end of the week as I'll be in a mandatory meeting up north
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Mountain Pass
Joined: Dec 2025
Posts: 104
Likes: 46
Gotcha... The idle time is what I'm really interested in... Idle is hard on the 6.8 and 7.3l. The OLM should be coming on sooner with a lot of idle. So if they are going 10k between LOF's AND they have a ton of idle time, thats a bad combo... Asking for trouble.. My fleet customers OLM alerts come on around 7-8k because they are either working them hard in the F550s or doing a ton of idling like in the forman trucks.
Lead Driver
Joined: Feb 2005
Posts: 7,923
Likes: 2,642
From: The Great State of Texas
I'll check idle hours. Oil has been changed almost exclusively at the dealership. As far as the walls getting scored, I think it may be due to the oil squirters spraying the metal off the failing lobe and roller onto the cylinder wall. I won't be able to get any further details til the end of the week as I'll be in a mandatory meeting up north
Lead Driver
Joined: Feb 2005
Posts: 7,923
Likes: 2,642
From: The Great State of Texas
Gotcha... The idle time is what I'm really interested in... Idle is hard on the 6.8 and 7.3l. The OLM should be coming on sooner with a lot of idle. So if they are going 10k between LOF's AND they have a ton of idle time, thats a bad combo... Asking for trouble.. My fleet customers OLM alerts come on around 7-8k because they are either working them hard in the F550s or doing a ton of idling like in the forman trucks.
Laughing Gas
Joined: Nov 2010
Posts: 792
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Scoring could be loss of oil pressure caused by broken lifter that creates a "leak" and drop in pressure. Could be caused by incomplete combustion and fuel washing oil off cylinder wall because valves may not fully close or fully open depending on which lifter failed. Etc etc etc etc.
Mountain Pass
Joined: Dec 2025
Posts: 104
Likes: 46
Ford may have fixed it by now, but really the only failures seen on the 7.3 when they first came out in 2020 was lifter failures, but only on ones that did a ton of idling. For example an airport shuttle buses. The 7.3l oil pump changed for 2023. Hopefully that was a design change that included a couple extra psi of oil pressure.
FishOnOne. Yep power companies are hard on everything. Idling all day. One of my fleet customers bought 3 Duke energy trucks at Auction that all had about 100k on them.. He thought he got a great deal. He didn't ask me before doing so.. When factoring in idle time they all had more like 350k on all of them. An idle hour meter is prob one of the best features ford added.... .
FishOnOne. Yep power companies are hard on everything. Idling all day. One of my fleet customers bought 3 Duke energy trucks at Auction that all had about 100k on them.. He thought he got a great deal. He didn't ask me before doing so.. When factoring in idle time they all had more like 350k on all of them. An idle hour meter is prob one of the best features ford added.... .
Last edited by LEEDSnDeed; May 4, 2026 at 05:00 PM.
