Ok, it's supposed to be 8 cylinders but the relative compression test shows 6. It has cylinder contribution and misfire codes. I'm betting on the TSB for broken injector hold down being the culprit here. I finally get to break into one of these. Been waiting 5 years.
2011 Ford 6.7 6 Cylinder
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Be sure to look for broken exhaust valves. Low compression is becoming way more common on these engines, unfortunately. When the 6.7 was launched I was sure it was a better engine than the 6.0 and 6.4. Now I'm seeing a bunch of them with the bottom ends wiped out. All cab and chassis stuff.
Joe"You don't build a reputation on what you're going to do"
Henry FordComment
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Yep, you are right about that. Hold downs look good. Digging deeper. What scares me a bit is that for as bad as the relative compression test looked (and I did it multiple times to be sure) it didn't run quite that bad but it was missing and injector trims were all over the place. Number 3 being the most concerning on the kill test as well.Comment
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Spoke too soon. I couldn't get a good look at the left side until I got cab off. Never question the relative compression test if done properly. Got broken hold downs on cylinders 5 and 8. I didn't even notice until I started to loosen the fuel line from the injector and noticed that the injector started to move. The plastic return fuel lines did not break and no fuel leakage. this has been a back burner project, gotta get serious about it now. the right side is easily accessible, the left side not so much. I had so much stuff disconnected I decided to lift the cab. Probably not really necessary for injector removal. Maybe even heads . The reverse flow thing is a little weird as is a turbo with 2 inlets. And vacuum power brakes on a diesel ? I hope that vacuum pump is bullet proof.Last edited by greasybob; 04-22-2016, 04:17 AM.Comment
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Well it turns out that the injector hold downs were not the problem. I think they broke when I tried to loosen the lines from the injectors. Had the hold downs been broken the injectors should have been covered in soot and they were not. I got the new hold downs, improved ones are stamped steel instead of cast. I installed new washers and O rings on the injectors, but before re-assembling anything else I hooked up a couple of batteries to the starter and did the relative compression test again. Still only 6 cylinders with compression. This time because I had the plenum off I could hear it weezing through the right intake while cranking. So off with the heads. I found cylinders 3 and 4 black and sooted up while the rest were clean around the center of the head. Sent them off to the machine shop. Called back with the news of broken intake valve guides and bent intake valves for the 2 cylinders in question. Also told me that all 16 exhaust valves had cracks on the valve faces. So I'll wait until the heads are repaired and we will try again.Attached FilesComment
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No deletes or tuners, just stock. It's back together now and runs great. I had to replace the no. 5 injector also to satisfy the fuel trims. Just when you thought things couldn't get any more crowded under the hood I came across this 2012 F450 6.7 with a hydraulic pump added on. It's a Muncie kit. The after market fan hub need to be replaced. With this kit on the accessory belt is looped through the hydraulic pump belt tension/idler bracket so replace the belt and you remove the coolers first. It just keeps getting better.Attached FilesComment
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