X15 noise and lack of power on a hard pull.

[Jrloar]

I now have a 2018 T680 with a 2017 X15. What I have noticed on a hard pull is it feels like it has a miss Almost like a flat spot on a tire when it pulls down to around 1100 rpms. I can also hear it, it sounds kinda like my ISX did when idling ( timing chin noise I guess ) but much much louder. It has just shy of 300k on it and no codes. I have ran injector tests and they all have good results. Is this a normal feeling for this engine? I take it to the shop this week because it’s under warranty from the place I got the truck but I don’t want to look stupid if this engine normally runs like this.

Hope this makes since. Thanks in advance for any input.

[marek4792]

Not sure what your specs are but it's pretty much known here that you do not lug a Cummins below 1300 under any circumstance, have you ran an overhead yet you very well could have a bad camshaft already yes it's very common issue, also its about that time to rebuild that fuel pump they still fail like the older isx's but will not contaminate the oil passages. Have you done an egr tuneup yet?

[tree98]

Lugging it that low would probably cause mysterious noises, very very bad thing to do.

[Unilevers]

ha

[Rawze]

Have you done an injector leak down test? - If so, what is the leak rate?

[Jrloar]

(12-17-2019 )marek4792 Wrote:  Not sure what your specs are but it's pretty much known here that you do not lug a Cummins below 1300 under any circumstance, have you ran an overhead yet you very well could have a bad camshaft already yes it's very common issue, also its about that time to rebuild that fuel pump they still fail like the older isx's but will not contaminate the oil passages. Have you done an egr tuneup yet?

It’s an auto so where it shifts is how it was programmed from the factory. Remember all newer engines are programmed to run low RPS. The same year PACCAR I had shifted about the same RPM. However my brother has one only two years older and it won’t run that low of youR life depended on it. No EGR tuneup that I know of. However the shop that worked on it before I got it said the overhead was done less that 30k ago.
I did The injector test for pressure build but not leak-down. It builds just over 30k psi. I will do a leak down tomorrow when I get to my receiver.
The noise sounds more like if a timing chain has slop in it and the lobes on the cam are making it slap around along with a thumping clunking banging noise. I talked to the shop Wednesday and they told me to just run it and if it gets worse bring it back. I just got the truck two weeks ago so I dang sure don’t need any down time at the moment.

I will attempt to get a recording of it the next time I’m in the hills. Although I was running 80-85 across Texas today so my Rs were around 1600 and I could hear it plain as day. Just no where close to as loud as when it’s up there in 8th.

[marek4792]

Cummins/Eaton do program their engines for low rpm but the problem is that Cummins didn't design it for low rpm like Paccar and even Volvo has!! Cummins engines have a mid stop liner design that is very notorious for fretting and blowing head gaskets due to low rpm high torque operation. Also I know Texas has got big speed limits and even I and some of us here like driving fast too but I'd back it down to 75 due to tire ratings if you gotta go fast but slower the better is the game here. Does the noise follow road speed or engine speed? Did you change tires recently are they mounted/balanced properly? Any vibrations when it "misses"? What's your average fuel economy? What terrain and equipment do you run? Sounds like you got 3.08s for rears? Usually you don't see that tall of gear unless it's a direct drive transmission like Paccar and Volvo which usually run 2.64 gears and that tall of rears paired with an overdrive trans is very detrimental to performance, fuel economy and your liners in high demand situations. What you have is a very poorly spec'd truck that is destined for failure!

[Waterloo]

(12-22-2019 )Jrloar Wrote:  The noise sounds more like if a timing chain has slop in it and the lobes on the cam are making it slap around along with a thumping clunking banging noise. I talked to the shop Wednesday and they told me to just run it and if it gets worse bring it back.

That sounds normal, the shop telling you to run it and bring it back when it breaks. Brother, shut that thing down and find out what is wrong with it! That auto transmission, it should be able to be adjusted in regards to shift points via software, that needs to be done before you blow a liner, if you haven't already.

Banging noises coming from the motor is not normal, and there are no timing chains, just gears. Have you looked at the camshaft? You, not this idiot telling you to run the truck.

What is the coolant level like? Is it fluctuating wildly or coming out of the coolant bottle? Have you had to add any?

Fuel pump, get that rebuilt ASAP.

SLOW DOWN! Learn how to manually shift the truck to keep those RPM's up over 1400. These motors are best run at 1600 RPM. You need to learn how to hold the truck at 1600 RPM at a more sensible speed, Running 80 mph will get you or someone else killed, hell the tires are only rated at 70 mph.

I would bet that nothing has been serviced on this truck, maybe a few oil changes and that is it. This sounds like another end of life truck in need of an in frame from neglect. I wonder what the rest of this truck looks like?

Brother, you need to shut that truck down and get it properly diagnosed. This is not a game, and these trucks are built to fail unless treated with kid gloves, and few if any are. Get a load to Atlanta and go see Mr Hagg. Me, I would call him Monday and get the truck in there to a real mechanic.

[Camstyn]

Yup, probably not what you wanted to hear but you are getting good advice here. Either get your transmission reprogrammed to keep above 1400rpm or use the manual mode on the shifter to do it yourself to avoid ruining the engine. Hopefully whatever you’re noticing with it now isn’t anything major, but running that engine hard at low RPM’s is going to cause you big problems.

My X15 starts to feel and sound unhappy at anything under 1400rpm, vibration and noises that are avoidable by keeping the RPM’s up out of that range.