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ISX and DD15 Valve Trains... - BigRed6 - 06-13-2020
Newbie Alert!
I'm looking at trucks to purchase one. (no stealer/salespeople please) I'm a good mechanic, and I agree with the Rawze philosophy of both self-repair and intelligent, fuel-saving and safe driving. (OOG, hmmm...)
I have watched many of Rawze's repair videos, ISX rebuild, Headset, EGR Maint., etc...
I have also watched a bunch of DD15 repair videos, and like Francisco Amaya's work.
He had a DD15 that was running super rough - undriveable. The bolts had come loose on the cam mount blocks - the ALUMINUM cam mount blocks. The steel bolts had stripped-out of the Aluminum blocks. These blocks hold the cams down and the rocker tubes above them. He removed the cam blocks and sent them to a machine shop to get thread inserts put in that were replacing the factory helicoils!
This seems like the wrong place to put an aluminum block to hold down such important equipment with continuous stress, heat and wear that require such close tolerances. Seeing that video alone made me think that Mercedes had far more influence on Detroit than it appears. I can't imagine the weight savings outweighing the potential loss of reliability on that design.
I like that the ISX has steel parts up in the valve train. (please correct me if I'm wrong, but everything looked and sounded like steel and cast iron.)
That DD15 stripped threads problem alone is one reason I've decided to only look at trucks with a Cummins ISX or X15 engine. Overall, it seems to be a simpler but stronger-built engine.
I'd like to hear from other mechanics who have worked on both engines, know the repair/reliability history of both, etc...
If you drive and don't do your own mechanic work, please don't tell me how great your engine has been. Good measured driving can cover for a bad mechanical design for a long time. I'm not trying to start a "what's your favorite contest" here, just trying to get real facts on the engine designs and typical failures. I try to stay unbiased until something blatantly bad repels me from a mechanical design. It may not be a deal-breaker, but it all adds up on the pros and cons list. I want a rig that has a chance from the start to be somewhat reliable and not kill itself due to a design meant to keep the stealership shops busy or sell new trucks every couple years.
I have a hard time seeing aluminum in a big rig diesel engine, although I'm sure both have some and each have their set of weaknesses and cool stuff.
Also, rocker injection vs. common rail high-pressure injection in the ISX series. Who likes what and why? Do you think the X15 is a true improvement over the ISX?
I live in Nevada and have to drive into California many times per week, so, my truck has to be 2014 or newer for smog qualifications.
Thank you for your time and info on this!
RE: ISX and DD15 Valve Trains... - Waterloo - 06-13-2020
Well, I don't own a Detroit, but have been in the plant in Redford MI where they build them, and in the bar across the street where the workers hang out from the plant. I have talked to more than a few of the guys that work there, the motors they make are no longer the quality they are used to building. They recommended not purchasing due to quality and assembly issues, like the cam shafts with the pressed on lobes. And seeing how much plastic is on these motors honesty blew my mind. Even the oil pans are now plastic, seriously?
With the ISX, I can at least work on the motor, an Inline reader and a copy of Insite, along with a free subscription to Cummins Quickserve... If you wrench and do not have access to thousands of dollars in software and manuals, Cummins is the only way to go.
Rawze helped me in frame my CM-871 in his driveway... I used my iPhone and a bag of tools I brought along. Rawze was there to cut the block, help set the head and pistons, the rest was on me where two sets of hands were not required along with a kick in the arse a few times. None of that would have happened if I had one of these new Detroit, PACCCAR, etc., motors.
Just my .02 as an owner that really does work on his truck. And yes, plenty of steel and iron on the ISX, the front structure is about the only place you need to watch yourself. Be gentle and all will be good, no rattle guns, stick to hand tools and you should have no issues. If not, Heli-Coil to the rescue! I will stick with the ISX for the main reason the diagnostics and tools are readily available, that is the only reason, I am not a fanboy of any of these EPA motors. Give me a reliable old Series 60 or 6NZ Cat and I would be more than happy.
RE: ISX and DD15 Valve Trains... - BigRed6 - 06-14-2020
Thanks for the info Waterloo. I'm in Nevada and we can run older trucks, but I have to go into California for short runs quite a bit, so, gotta have a late-model truck. I have been stopped 4 times in my '97 International 4700 pulling a Big Tex 25k Gooseneck Trailer - EMPTY! They're getting very picky about older trucks. Even more picky if you don't have your permits or an apportioned truck. First thing they ask "do you have your temp permits for California?" Hence the reason for a newer truck with full DOT Apportionment. Tired of being stopped, even though the permits are in the front window.
Is the DD15 a Mercedes design/derivative? It sure looks euro style.
All the Best!
RE: ISX and DD15 Valve Trains... - BigRed6 - 06-14-2020
Has anyone out there worked on an X15? Differences in performance/reliability/no starts between ISX Rocker Injection and High Pressure Common Rail? Thanks!
RE: ISX and DD15 Valve Trains... - BigRed6 - 06-14-2020
Also, Rawze, anyone - Cummins OTR Tuning on the fly for the X15??? Sounds like a disaster waiting to happen... has anyone ever had this done?
RE: ISX and DD15 Valve Trains... - tree98 - 06-14-2020
(06-14-2020 )BigRed6 Wrote: Has anyone out there worked on an X15? Differences in performance/reliability/no starts between ISX Rocker Injection and High Pressure Common Rail? Thanks!
Except for higher compression ratio, fuel pump shrapnel isolation,and a crappy turbo actuator, the X15 is essentially just another 2350.
RE: ISX and DD15 Valve Trains... - BigRed6 - 06-14-2020
Thanks $tree98. Good to know. What's the fix for the turbo actuator?
RE: ISX and DD15 Valve Trains... - tree98 - 06-14-2020
(06-14-2020 )BigRed6 Wrote: What's the fix for the turbo actuator?
I've never had one open yet but Rawze said they don't use bearings anymore, they use bushings and i think there we're other things he mentioned about them being made cheaper. I wonder if the bushings could be replaced with bearings and the other things updated as well ?? Maybe Rawze will chime in.
RE: ISX and DD15 Valve Trains... - Rawze - 06-14-2020
(This is only personal opinion based on what I have seen so far) ...
They appear to be the same actuator as the newest style of VERY POORLY MADE 351Ve actuators that are now used on the dodge pickups. The guy at YTS said they fail like mad on the pickup trucks due to vibration and all the no-solder connections in them. That or the heat gets the Teflon bushings where bearings should be. The older versions of those actuators were actually well built. The guy at YTS also confirmed that the older ones held up very well, would usually last the life of the engine (at least in automotive standards any ways). - I have seen both styles apart. You can tell the older ones from the newer ones by the electrical connector. - If it has a pig-tail connector on it, it is the older style and quite well built. ... But all the newer junky style that I have seen so far have the electrical connector mounted directly into the top of the actuator with no pig-tail at all.
The newer ones are mostly complete garbage in my opinion after seeing the insides of a few of them with detail. A lot of glue and no-solder connections, motor windings with insulation still on them shoved into "V" solder-less connectors, expansion pins for all the connections to and from the circuit board, flaky looking as all he@ll and poorly put together. Teflon bushings where used where bearings should be, etc. - Then to top it all off,. they glued to all hell, its insides to prevent all the solder-less connections from flaking out too badly. - Really cheesy design compared to any of the older style VG actuators. - Only time will reveal their actual track record on the ISX though, so lets see what the future holds for them.