Longevity questions. Are 6.4s worth building

alwaysdiesel · Sep 20, 2016

I've been doing research on 6.4s and 6.7s for the last year or so, looking to drop one in an OBS. I'm having a hard time picking the 6.4 because their reputation for being reliable is awful even with work being done.

I just finished doing a HPFP and full EGR D***** on my dads truck because the harness shorted and shut the truck down. I had to pull the cab because the up pipe bolts rounded off. It was my first real good experience with a 6.4. Only work on it prior was services, *** D*****, top rad hose update and fixing a plugged heater core. Digging into the truck a little more, it seems like the engineering of the 6.4 isn't super great. It seems there are lot's of areas to improve on to make things simpler and stronger. Overall, the engine itself doesn't seem overly complicated or cluttered, and I think it could work in an OBS engine bay. My biggest concern is that the engines can be lemons no matter what mods are done. I hear advice given all the time to stay away from them (more so than 6.0s) and it makes me wonder. I've learned of the following common issues: *** clogging, EGR coolers cracking, oil dilution, K16 PCV sticking, Lifters failing, pistons cracking, turbo failure and a large ring gap from factory resulting in blowby and oil dilution.

In my mind, all of those can be dealt with. The K16 PCV issue would be tough since they seem to be fairly unpredictable and not quick to get at for repair. Other than that, I don't see why an engine can't be built with delipped pistons, fully D***** with solid lifters, single non VGT or Non VGT compounds and not have to worry about the common problems. Is this work just beyond what most average truck owners are willing to do?

I need an honest answer and I know some of the most well built 6.4s are on this forum, guys who know all the engine quirks and deal with them enough to say if they are worth it or not.

White_monster · Sep 20, 2016

I'm happy with my 6.4. Had it since new in 08 and it's been fine. Still.on my original K16 pump in the valley at 120k miles. They have issues but so does everything. I believe it comes down to maintenence and the care that is given to it.

jdgleason · Sep 20, 2016

100% agreed with Shane. I ordered my truck and it's really never given me any issues that I didn't ask for. Truck is sound and the motors handle power better than any other PowerStroke does imo.

alwaysdiesel · Sep 20, 2016

I almost feel like the compound turbos coming stock is their biggest downfall in terms of reliability. Guys know they have lots of air so they throw it on hot tune and hammer down, then they bitch when the pistons crack or the turbos go out.
Does anyone have more to add in terms of factory issues that should be addressed while the engine is out?

powerstroked08 · Sep 20, 2016

The pistons cracking is pretty much just a random sh!t luck thing. Honestly, there are trucks that are north of 1k hp on a stock bottom end holding up fine. While there are sub 4-500 hp trucks popping pistons just gently cruising up the road. I really think there is a flaw in some of the castings, not to mention the major lip that is on the stock pistons that is contributing to the failures. But back on topic. The 6.4 in MY opinion is a great motor, while it has flaws(like any other engine) it can make and handle a ton of power. But like stated before you have to maintain the damn thing. Mainly the fuel. This is a common rail. It NEEDS CLEAN FUEL. I can't stress this enough! So with that said I say 6.4, but that's just me.

TyCorr · Sep 20, 2016

But there are ALOT of bone stock trucks. A lot. With around 100k on them and completely trashed motors.

That's not normal.

powerstrokelyfe · Sep 21, 2016

^ unfortunately, definitely true

My09Ride · Sep 21, 2016

Know a couple of Ford Diesel Tech pretty well. In several conversations they told me that most of the problems they see is neglect, and lack of maintenance. Oil not changed, fuel filter not changed, separator not drained, and cooling system neglected. This includes most of the diesels, esp. the 6.4. I guess they likes to be loved. I am 63K miles no major problems

thatsmokinobs · Sep 21, 2016

My dad's 6.4 destroyed itself at 110k ish. Bone stock, but no idea how the previous owners took care of it. I think it's all about the maintenance and getting rid of the emissions stuff. It's not a ford 300, you gotta take care of it.

Layson · Sep 21, 2016

TyCorr said:
But there are ALOT of bone stock trucks. A lot. With around 100k on them and completely trashed motors.

That's not normal.

Oh yes. Every one of the trucks that is sold from our fleet at auction is non operable and low miles. They are all completely stock and for the most part fairly well maintained.

ckrueg · Sep 21, 2016

I bought my 2010 with 275k on the clock and it has zero issues with 350k on it now. AFAIK it is the original engine and it was ******d on a stock tune when I bought it. I ran it for 50k on my own custom mcc tunes probably around 500 rwhp. That said I ended up getting a 6.7 after looking at about 4 6.4s that had noisy rockers, tons of blowby and contribution codes, and a toasted tranny. It seems like if you get one that was maintained well it should last but I didn't want to risk having to drop 10k into one and still have a 6+year old truck. Plus the deals on 2016 trucks made it worth it in my mind. I sold my 6.4 to my brother and I still do the maintenance and drive it on occasion so I'll still post up if it has issues.

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300000 and counting · Sep 21, 2016

If your already spending the money I'd go with the 6.7, they are a lot more reliable and you have a 6th gear in the tranny. Either way you go about it your basically doing the same amount of work, I would go with the one with the better reputation.

thatsmokinobs · Sep 21, 2016

And a 6.7 would be way cooler imo

Rubenk · Sep 21, 2016

You have to realize it was only a 3 year model truck and engine. Parts availability and aftermarket solutions are actually pretty limited compared to other platforms. Yes its a monster capable of alot, but there are limitations all tied back to its 3 year run. You're really at the mercy of parts remanufacturers for alot of things.

A 6.0 despite its reputation might be a better choice. A 6.7 would be great too, but probably price limited.

superpsd · Sep 21, 2016

Funny you mentioned dropping one in a OBS. I have been at the drawing board for the exact same swap. I have been kicking the idea of building a 6.7 OBS. I have been shopping around for a good 6.7 but no good deals yet. Every motor I have looked at in the yards that isnt 8-10K is trashed and missing half the goods. Im also planning to avoid the factory pcm and go stand alone which has its hurdles as well. So far i have just sat back and have been learning about the 6.7 and commonrail control. My largest hurdle ia planning it out and finding good deals so im not into the rig cash wise more than a good 6.7 turn key truck. Prices on the 6.7 are coming down but not fast enough yet. There was a complete 6.7 drivetrain in flordia the other day on ebay for 4K out of a rolled truck. Best way to go would likely find a complete salvaged truck that you can hear run.

powerstrokelyfe · Sep 22, 2016

Op, a 6.0 may be a good option for you. As said above, A 6.7 over a 6.4 is the better of the 2.

alwaysdiesel · Sep 24, 2016

I am drawn to the 6.4 over the 6.7 right now. My guess is I've driven and wrenched a 6.4 so I'm more comfortable with it. i'm sure if I get some time on a 6.7 my opinion will change. The fact that the 6.4 was only produced for 3 years does worry me for the future though. With the engine not having a great reputation means it will most likely be hard to come by parts in 10-15 years, and it's already 6 years gone

I'm not completely opposed to a 6.0 either, but I like the idea of common rail especially because I will be in cold climates and may be in remote locations where I won't be able to plug in any pan heaters or anything. Overall, I'm probably best off with a 6.7. More displacement, more years in production and so far a fairly good reputation. The 2017s have the same 6.7 in the new body design so it's probably guaranteed to stay for two more years at the minimum, making close to 10 years of production minimum.

alwaysdiesel · Sep 24, 2016

superpsd said:
Funny you mentioned dropping one in a OBS. I have been at the drawing board for the exact same swap. I have been kicking the idea of building a 6.7 OBS. I have been shopping around for a good 6.7 but no good deals yet. Every motor I have looked at in the yards that isnt 8-10K is trashed and missing half the goods. Im also planning to avoid the factory pcm and go stand alone which has its hurdles as well. So far i have just sat back and have been learning about the 6.7 and commonrail control. My largest hurdle ia planning it out and finding good deals so im not into the rig cash wise more than a good 6.7 turn key truck. Prices on the 6.7 are coming down but not fast enough yet. There was a complete 6.7 drivetrain in flordia the other day on ebay for 4K out of a rolled truck. Best way to go would likely find a complete salvaged truck that you can hear run.

That's honestly the scary point. It doesn't take much and the cost is getting up into a brand new pickup range, and at the end of the day you're driving an old body that doesn't have navigation, ac seats, storage compartments etc (Well it might

) I ripped apart my 94 two years ago, frame off, 08 axle conversion and a 96 12 valve to replace the IDI. I got a deal on my axles and engine and still, what I have into it I could be driving something 15 years newer. I don't regret it but I understand how quickly the costs add up.
Now talking about expensive common rail fuel components and electronically controlled everything, it adds up even faster. Not to mention if you have to buy any parts directly from Ford, it runs up the bill real quick. Lots to consider.