|Topic Review (Newest First)|
|07-02-2019 10:59 PM|
When it is feasible these days they use new engine assemblies and short blocks. The heavily automated assembly is cheaper than the labor to take apart, inspect, measure, machine, and re-assemble the core in a manual way. When the 6.7 goes away or changes in some major way so that earlier engine pieces will not fit then they will be forced to farm out cores for remanufacture. I hope that day doesn't come for a decade.
I am unsure if the balancer change can be done by itself or if the flywheel/flex plate is also different. I also don't know if the crank breakage is all on the balancer change or if there were other changes in manufacture of the pieces that improved strength and quality. Maybe someone with more knowledge on this will chime in.
|07-02-2019 05:14 PM|
Originally Posted by jimmy View Post
|07-02-2019 03:32 PM|
There are many possibilities. They changed the harmonic balancer in 2015 engine update. The main that seems to have the high failure may be a resonance point for crankshaft and maybe that is the cause and balancer diminishes failures. There a lot of these engine with over 200K of daily cattle trailer, hot shot, and other uses where they run high load and drag stuff up hills working hard and with high oil temps and they do not fail. Lots of users buying lots more with 6.7s due to their history with their 11, 12, and 13 year models. None of that makes you feel any better when yours craps out.
I worked for a car and truck manufacturer for about 30 years. They dropped bearing tangs due to manufacturing changes a couple of decades ago. Some on commercial diesel engines and lots of very high specific torque and HP engines with aluminum blocks. Not direct comparison but high relevance. The install of those tangless sheels in their case is with a positioning jig so install position is as accurate as with tangs. I asked a seasoned engineer several years back and he said that if the tangless shells failed there was a reason that would have destroyed tanged shells. That still is no absolute answer as there could be a block distortion that distorts the block and lets the bearing fail and starve the rod bearings. Some very interesting developments have been made in the last years to bearings to make them compliant with lead free laws while increasing durability. Then we have some new polymeric coatings to assure engines, both diesel and gasoline fueled, have unchanged service life with stop/start feature. I think bearing changes may have been part of the 2015 update but maybe that was 2017. I can't find the article(s) where I read about those changes on 6.7. Do any included instrutions mention balncer change on your short block or did it include that part?
|07-02-2019 01:05 PM|
2. The close up of the bearing in the 3rd pic of my second post is in fact the #2 main bearing lower half. I think even Ray Charles can see that bearing spun. I think it shifted some until it blocked the oil hole then starved the main and rod for oil. This is indicated by the flange that is formed on the edge of the bearing from side contact. For those that aren't aware of it, the oil has to flow through the upper half of the main bearing. if the half is out of position it will block the oil flow to that main and the rod bearing that feeds off of that main.
3. The oil galley in the block was, as I stated clear.
4. How would there be a blockage in only 1 oil galley? On the engines that have been torn down it is almost always these particular bearings that fail. A Ford diesel tech buddy of mine said every one of these that they have torn down to inspect is #2 & #6 rods bearings, why? The only bearings affected are fed oil through the #2 main bearing, the rest look like new.
|07-02-2019 12:16 PM|
|larrgh||Well, unless one can determine the root cause of the failure, which appears to to oil starvation to the main bearing and #2 rod, one can suppose all they want about whether tangs or no tangs are the root cause. It doesn't appear that the main bear that supplies oil to #2 rod has spun from your photos. If it didn't spin, there should be no stoppage of oil to the rod bearing as the upper main bearing is grooved unless there was stoppage of the oil circuit within the block. I would suspect something in the oil galley might be the root cause of the failure.|
|07-02-2019 11:11 AM|
|07-02-2019 10:22 AM|
Originally Posted by gearhead1011 View Post
You have to remember that Ford "boxed" the frame on the 2017 and newer trucks. This may have necessitated the need to strengthen the block mounts. Since neither have an old and new block for side by side comparison nor was any block photos provided in this thread, one must assume Ford updated the mounts due to the new frame construction.
Maybe Keith aka Ford Doctor will chime in and help with the analysis.
Oh, and the main reason for using dowels in aluminum rods has to do the the expansion of the materials used, i.e., aluminum verses steel. One could probably not get adequate bearing crush once the rod reaches normalize operating temperatures and has achieved. max expansion.
|07-02-2019 09:07 AM|
Dowels are still used in high performance aluminum connecting rods. I know this an extreme application but to be sure there is a reason for it.
Why would Ford go to the expense of changing the engine mount brackets if not to decrease distortion? I have never heard of one breaking. I don't think it's coincidence that these failures start with a main bearing web that is lined up with 2 bolts from the bracket. The 2 rear bolts are staggered so that part of the load is spread out. With high performance race engines we use motor plates instead of the side mounted motor mounts. The main reason for this is to prevent the distortion of the center cylinders caused by the force applied to the center of the block.
|07-02-2019 06:20 AM|
|larrgh||Going back and looking at the photos, it appears the spun rod bearing failure started with the main bearing failing first. Oil starved or clogged oil passage or some unknown reason stopped adequate flow of oil to the main bearing which supplies oil to the rod bearing. The main bearing starving the rod bearing of oil, caused the rod bearing to overheat, excess wear and then to spin within the rod. Tangs, as you seem to think would prevent bearings from spinning, would not have prevented the bearing in the rod from spinning if this case.|
|07-02-2019 05:35 AM|
Originally Posted by klhansen View Post
You can disagree all you want. The tangs are only used for alignment during insertion.
Google it. you will find out tangs do not prevent bearings from spinning. Even the Dodge hemi Hellcat motor uses tangle bearings.
and video about bearings.
|07-02-2019 02:56 AM|
|07-01-2019 08:20 PM|
Originally Posted by klhansen View Post
Tangs on bearings do NOT prevent bearings from spinning. That is an old wives tale. They are only there for bearing locating during assembly. The bearing crush prevents the bearings from spinning. This applies to both main and rod bearings.
Dowels in the bearings haven't been used in many many years and was only rarely used.
Also, I highly doubt the engine mounts caused any distortion that attributed to the bearings spinning. Appears from researching the Ford Parts Catalog, the engine mount bracket was revised beginning with the 2017 models. Doesn't appear to be any relation to possible bearing issues in the 2011-2016 engines.
|07-01-2019 07:47 PM|
Thanks for posting the teardown info. Good for all to have.
If I had a 6.7 I might consider replacing the engine mount bracket with the updated one, although that might require drilling and tapping the block for the larger bolts.
What puzzles me is why Ford would even consider using bearing inserts that aren't positively keyed in place with a tang or dowel. I'd almost blame the engineer who didn't stand up to the beancounter who said "that's too expensive".
|07-01-2019 07:08 PM|
All of the information I have gathered on this type of failure seems to indicate this failure is not that uncommon and it's almost always the #2 & #5 rod bearings. So I wanted to look closely at this to see why.
I'm confident that I know what caused my bearing failure and probably all of the other 2/6 rod bearing failures that have occurred on these 6.7s. The layout on the engine block has the 2 front engine mount bracket bolts on both sides of this engine lining up with the #2 main bearing web. I am convinced that what happens is the main bearing bore is distorted when these trucks are under load and eventually the tangless bearing shifts. When the bearing shifts enough the oil passage from the block to the main bearing is blocked. Once this happens the oil supply is reduced or cut off to not only the #2 main bearing but also to the #2 connecting rod bearing which is lubed through a passage in the crankshaft from the main bearing to the rod bearing. We know what happens to engine bearings that are run without oil. The #2 rod bearing spreads out and pushes into the #5 rod bearing which is on the same throw of the crankshaft. So the #5 rod bearing becomes collateral damage from the failed #2 rod bearing. In the pics you can see the the main bearing has a flange formed on the edge of it from where it shifted laterally and was running against the throw of the crankshaft. You can also see the damage to the crankshaft is much worse on the #2 rod bearing than the #5 which supports the idea that #5 is damaged from the #2 failure.
Now the good part. Ford has to know about this problem because the replacement engine addresses the cause of this failure. When I ordered the replacement short block my parts guy told me I had to replace the engine mount brackets. When I took them out of the box I thought why? They look the same as the originals BUT there is a difference. The first thing I noticed is the 10mm bolts that attach the brackets to the block are replaced with 12mm bolts. Looking a little closer I found the flanges on the mount brackets are thicker than the original brackets. The only reason I can think of for this change is to reduce or eliminate the distortion on the #2 main bearing journal.
Now I know there are plenty of these trucks that don't experience this failure and it makes a person wonder what happens that some of them do. I feel like there are machining tolerances and quite possibly the engines that fail are on the edge of those tolerances and that along with the tangless bearing is a recipe for failure. Because these use a tangless bearing it's also possible that some of these 6.7s are assembled with the bearings not centered up as well as some others. It would be nice if Ford would own up to this and make it right for the people footing the bill for their failure.
|05-27-2019 07:38 PM|
Well it looks like it's my turn to be one of the few 6.7 engine failure negative stats. 2 weeks ago I was on my way to a race pulling a 36' enclosed car trailer. I had just traveled about 100 miles of interstate and had exited. Within a couple of miles of lower speed driving I noticed a slight flutter as I tipped in to the throttle. I lifted, checked the dash, no warnings or CEL so then I step back into the throttle. Yep, it was missing. I found a place to pull over within 1/2 mile of the problem starting and by the time I got pulled off the road it was knocking and squealing. I shut it down and called a buddy that was on the way to the same race. I keep a cheap code reader in the truck so I checked to find it did have a pending cylinder 2 contribution code. When my buddy arrived we unhooked the trailer and pushed the truck back into a parking spot. I called another buddy from back home that runs a wrecker service and let him know where the truck was, where I hid a valet key and where I wanted my truck delivered to. I was about 5 miles from the race and after considering giving up and going home I decided (with a little encouragement from my buddy) to go race. I'm glad I did but that's another story.
We are covered up with work at the shop so I didn't really get a chance to get into it right away. My 1st thought was a HPFP failure so I inspected the primary fuel filter & fuel rail pressure regulator and they were clean as a whistle. I scoped the cylinder and the piston looked like it might have been bumping the head so I dropped the oil pan to check for metal. Here's what I found.
I had an extended warranty Ford gave me because of on going emission problems that the local dealers couldn't fix. It would have covered this except it ran out the first part of April, of course. I called anyway and they let me know I'm on my own. Not complaining about that, I know the expiration date is just that.
I checked my options and considering the amount of metal in the pan I decided the most practical route was to order a Ford reman. short block. I started on it Friday after closing up and took advantage of a day off today to go pull it out and tear it down.
#2 rod had spun, #6 rod on the same journal is about ready to spin. #2 main is in bad shape. #5 & 7 rods look perfect as does #3 main. I can't see how this could be a lubrication or contamination problem because of the affected parts and where they lay out in the oil flow. This truck has just over 60,000 miles on it and of course has been well maintained and taken care of. Oil checked periodically, never ran low, never overheated. I do run a little fast on the highway but the truck isn't beat on. PM22A added every time it's fueled.
While tearing down I found at least 6 of the 8 mm head bolts so loose I could turn them in by hand. It makes me wonder what else was done wrong during the engine build. This truck was built in May of 2012 and I intentionally avoided buying an early build truck. I really almost expected to have a HPFP failure and that would be a little easier to take at 60K because Ford can't control what's in the fuel. To say I'm disappointed with the quality of my truck is an understatement. Like so many others on here that have had problems I have been a Ford guy ever since I started driving over 40 years ago. Everybody that knows me knows that I love this truck despite the other problems I have had. I'm not swearing off Fords because of this, I guess I have my eyes a little more open now. Ford can build just as big a piece of crap as any of the other manufacturers. So I will take my lumps and fix this truck. I will probably sell it before the warranty runs out on the new engine. I will not own another Ford diesel which is really too bad because I really love everything else about it. I just don't trust it anymore. I do like the newer superdutys and the 6.2 seems to be a more reliable engine so I might end up with one of those. I don't really have to have a diesel, I wanted one but not bad enough to buy an engine every 60K.