C-15 MXS valvetrain issues

Are the correct parts getting put in it? Cat has updated rocker arm studs and exhaust rockers, that on some serial numbers also need software and IAT sensors. But, the small IVA housing studs (ones with the spacers built in) are updated too. Ive put the updated studs in engines from 475-625 hp and never have had one come back. Maybe you could tell me some part numbers?

 

I have a MXS. The only problem I have had are the intake Act going out. With the 13 speed I shift at 1500/1550 and lug it down to 1250 or down to 1150 if I'm almost to the top of a hill. Are you takin your truck to a Dealer or to a Cat shop? Sounds like who ever is setting the value train up is not setting it right. The Cat shop I deal with has told me the MXS and NXS are the better of the Acert engines

 

Yeah, it can be difficult to set the overhead up right if they dont know what they are doing. In my opinion BXS and NXS C-15s are the most trouble free just because of the studs breaking on the MXS engines. If I had my choice Id rather have a BXS just because I never see them in the shop though. But if you decide to put new parts in yourself, let me know your s/n and I can get you the right info.

 

LOL... my truck is in the shop # Doonan Peterbilt in Wichita, KS because of this issue right now.... had to get towed in.... on the intake side .... they said "rocker arm bolt backed off" and "they're replacing the rocker arm" ... it is a c-15 acert engine which is a MXS if I am correct - LOL - looks like I am going to be in the shop again in the future according to y'all. I bought a CAT and a Pete as my first truck combo b/c for 10 years as a company driver that's what I heard was the VERY BEST and least amount of breakdowns... Funny, as a company driver I never was in the shop for drivetrain or valvetrain issues ... and all I ever drove was the evil freightshakers.

 

I am in an '08 Pete with the Acert Cat C-15 with about 280,000 miles on it.(I don't know the difference between MXS and NXS, never heard that till now).

All 3 bolts that hold down the rocker assembly on #3/#4 cylinders broke on me, I had to run it about 35 miles to get to safety. As of this moment I am waiting for the Cat rep to tell the mechanics if the head needs to come off or not

My shop mechanic told me that there is no service bulletin on this, but they have a "notice" out that says if a broken bolt is found, all the bolts should be replaced. That tells me that Cat put faulty bolts in there to begin with, but if they issued a bulletin then there could be a recall.

And I too have been told to lug down to as far as 1000 rpm, from a Cat rep too. "Keep your rpm's low, you can lug it down to 1100, and even 1000 if you are topping the hill. Stay under 1500." I have an 18 speed behind this motor.

Fuel mileage is terrible, abut 5.5 average. When it wants to, it will pull but that is about a 50/50 thing. 1 hill it pulls, the next hill it doesn't.

I was a Cat man until I got this one. Looking at the Cummins now.

 

pullingtrucker u sure your head is ok and not wore from the bolts breaking

 

You're allowed 19 thou (0.5mm) wear in the rocker saddles before you you have to replace the head. There is a TIB about it from cat.