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Short answer: EGR nuggets aka Carbon/Soot rocks was the cause
@toomanytoys will appreciate this
Long answer as well as the "Why" and "How":
The rocker arms on a 6.7 powerstroke are a maintenance item. Since 3 out 8 rocker arms were about to come off and destroy the engine, the customer wisely opted to have all 8 done with new Motorcraft parts. I was also installing a DCR for them as well so this was a "fix it right so I don't have to think about it" sort of situation. (The original concern was that there was water in the fuel system and that damage could occur.) Since the valve covers/intake manifold had to come off, I took the time to clean the ports in the heads and intake manifolds. Well, unbeknownst to me, somehow a chunk of carbon/soot found its way into Cylinder #3. It was thick and heavy enough that I couldn't turn the engine past a certain point to remove the CP4 and install the DCR. Having to install all new rocker arms further necessitated barring the engine over as part of the procedure for installing the rocker arms.
I took a borescope down each of the cylinders and found the large chunk of EGR soot and some dust sitting in cylinder #3.
How did I get this chunk of EGR carbon out?
I put an air nozzle in the glow plug bore with the rocker arms off, then pressurized the cylinder and caught the soot in a rag. The dust came out but the carbon chunk remained. I turned the engine back and forth by hand, crushing the carbon rock until it was fine dust. It didn't damage the cylinder wall but had me and the foreman thinking we unexpectedly needed a long block for this truck.
Before this was discovered, what we thought happened:
It's a known fact that the crank gear on a 6.7 Powerstroke is NOT keyed. Basically with enough of a shock (namely from a failed CP4) could knock the crank gear loose and/or out of time. It's fixable in frame, but most engine builders recommended replacing the crank and tig welding the crankshaft gear.
So that's what happened.
The lessons learned:
-If you're cleaning the intake manifolds/ valve covers, remove the rocker arms, get a brass brush, and go to town.
-Every 6.7 needs to have the air intake system cleaned. They are absolutely plugged with carbon and soot and it's a miracle how these trucks run with an intake full of carbon like that. The same goes for the upper and lower intake manifolds.
-The injector grommets in the camber cover are a maintenance item as well. They were leaking so bad, it ruined the plugs on the injector harness, caused a misfire, and was bad enough that it looked like the upper oil pan had a profuse leak. We ended up having to buy a new engine harness to replace the old.
Thank y'all for being here on this journey with a 2018 6.7.
When I pulled the intake from the 2012 I had to install a DPK, there was so much carbon buildup in the EGR chamber that I was surprise the engine got any air, so I can imagine what this must have been like After a really good cleaning, the engine did rum smoother afterwards.
Thanks for the tag, TD. I had to laugh; same old story.
For those who don't know me, I'm in the 6.0L world. I pulled down my Ford remanufactured 6.0L after 75k or service because of issues I was hearing. This was not part of the disaster work done by the Ford supplier, which is a story in itself, but with the refresh of the heads, I found this:
A mix of EGR carbon and CCV oil accumulates on the port-facing side of the intake valves. When you look at the exhaust valves, you see pitting in the valve face where carbon has broken off from the intake valves, entered the combustion chamber, and trapped between the valve and valve seat when the valve closes. Since the valves are softer stainless, the hot carbon pits the face of the valves.
With this engine, I left the EGR valve in place and working. The valve guides were not worn, and the valve stem seals were in good condition. Regarding the question of maintenance and driving style, I always have good oil maintenance, and I have a habit of doing a hard acceleration at the last stop sign/light before coming home to punch up the boost and clean the engine. Otherwise, I drive normally, including towing. I wouldn't say granny driving.
Typical of the intake valves; the most carbon was on the front cylinders, diminishing to the back cylinders. The intake manifold was a bear to clean out the oily carbon from the ports, chemicals, and pressure washer.
Not the worst exhaust valve, but I don't care to go through the entire video to find it. The hardened valve seats were fine.
From the video, I tagged where the valve inspection starts for anyone interested. Song appropriately chosen.
Absolutely Jack, thought you'd find this interesting
Originally Posted by senix
I wonder about some of this. Could some of this be attributed to the type of service this motor saw?
I mean little old lady's living in retirement community's a driving two miles at 25 mph in retirement community's would have all these problems.
If you are working the motor and changing the oil I don't see that you would have such a problem.
So what will the service interval be for the rocker arms and push rods and intake cleaning be?
From what I saw, oil changes were when they got around to it and it seemed like this truck either did a lot of idling or didn't see much freeway or hauling.
As for how often to replace the rocker arms and clean the intake manifolds: It's not listed as a maintenance item by Ford but I'd say every 75-100K. It would also be good practice to swap out the EGR cooler guts as well. Keep in mind the 2017 and newer guts don't clog as easily as the 11-16 but still I'd say it'd be good practice.
If I owned a 6.7, I'd drive it for a week or two to get to know it and what it may need, then under the knife it goes.
-Crank gear gets tig welded up
-DCR installed
-New rocker arms
-New Glow plugs
-Complete top end reseal
-EGR cooler guts swapped
-Complete carbon clean out. Period.
-Primary and secondary cooling systems will get flushed.
-2011/2012 upper oil pan
-PPE lower oil pan
-Metal cold side pipe
H&S Motorsports upper intake hoses
The truck would be down for another 2-3 weeks, maybe a month between waiting for parts and getting it all installed, but it'd be worth it.
Thanks for reminding me of this. I'll add this to a repair and maintenance package for the 6.7. It's not cheap, but it'll definitely help keep things cleaner, longer once the work is done.
And here i am in my 17 still running like new with over 300k having done nothing but oil changes on the OLM.🤔
It's so hit and miss with engines and the components attached to them. My 16 with only 68k miles on it which It's job is pulling the 5th wheel (16k#). Gets plenty a work out, never shorted on a regen, oil changed 5-7 mile range, no long idle time and yet the turbocharger needs replacing because of something electrical on it.
Maybe the gov can require more crap to be attached and choke the engine more. 🤔
And here i am in my 17 still running like new with over 300k having done nothing but oil changes on the OLM.🤔
Eh, remember all the complaints against the 3.5 Ecoboost and how it will clog the valves and the turbos will blow up? My Flex is over 10 years old now, 186K miles on the EB, and it still performs like new. Granted it does need a new timing chain as the tensioners bleed down after a time, but that is normal. All that hate on the 3.5 yet out of the 9 I have had since 2010, NONE have ever given me trouble.
Keep the CP4 isolated from the rest of the system and provide good fuel lubricity, and I don't see the 6.7 being a problem. It's all in how it is taken care of.
However, I do agree that the intake needs periodic cleaning as long as it has an EGR. That FASS system is too new to put any faith in it, but if it works as designed, that should eliminate any intake cleaning.
