Cam replacement cm2350

[Rawze]

(12-10-2020 )SemiSweet Wrote:  Hi everyone,
Recently picked up a 2015 Peterbilt with a CM 2350 in it. Sent an oil sample in for analysis after doing a full service on the truck and it came back with Iron @ 63ppm and Chromium @ 4ppm. After doing some research on this site it was clear I needed to investigate even though it was my first oil sample from the motor. As simple as it is, I removed the valve cover to inspect the cam and cam followers. I found exactly what I was dreading.....One of the cam lobes was destroyed.

I decided to dig right into it knowing that it will not get better and it will destroy the motor if not taken care of asap.

The base timing was aligned and pinned before removing the cam.

The question I have is do I need to go through the lash adjustment process with the cam Idler gear if I did not remove or disturb it? The only gear removed was the cam gear along with loosing the scissor gear as described in the service manual. Reviewing the procedure for installing the cam gear, there is no room for error in the 15 min window allotted for the Loctite to set.

Essentially re-installing the cam gear should keep the lash to where it was before removal? The service manual does state that removing only one gear requires that you verify the lash after reassembly.

Also, I do think remember reading somewhere on here that the factory lash spec is unnecessarily tight and could be adjusted for less gear noise and wear?

(no rockers in place yet) ... Make sure the engine is pinned and cam is wedged with the proper wedge.

Follow specific cleaning and prep procedures for preventing the cam gear slippage later on when installing that cam gear. Installing it properly is talked about in this post along with showing how to ensure it does not slip later on in a video ... http://rawze.com/forums/showthread.php?t...2#pid60202

Don't worry about the amount of lash in the cam idler gear until you have the cam gear fully installed, set, and torqued down.

After the cam gear is back in place, there is no real need to re-adjust the idler gear if only the cam gear was removed and the idler was not loosened. - (some humour here) -The same gear was used, it did not change size or grow new metal on it while sitting on a bench, the new cam is in exactly the same place in the head as the old one was, and nothing changed to make the clearance change. However, if you want to re-adjust it so open up the clearances, then I like to set it to 0.008" - 0.010" (between idler and cam gear) and 0.011" clearance to the other gear.

- Re-adjust all valve lash after re-installing the rockers according to quickserv.

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Ensure it does not fail again ....

* Ensure there is no way that crank case fumes can build pressure in the engine. Not replacing the crank case filter often enough causes premature cam failure because higher than normal CC pressures it starves the top end of oil. Many people switch over and use a maintenence free CC filter and this helps prevent this. Here is a maint. free one: http://rawze.com/forums/showthread.php?t...50#pid8950

* Ensure the overhead valves are adjusted every 250k miles.

* The ISX does not like extended oil changes and a lot of failed cams have happened when people use those bypass systems and extend their oil changes.

* Based your oil changes on fuel mileage (or equivalent engine hours). -- (At the bottom of post in this link - http://rawze.com/forums/showthread.php?t...617#pid617 ). The general rule of thumb for oil changes on the ISX is ...

Rawze Wrote:If your average fuel mileage every 10,000 miles is ...

less than 5 MG -- Change your oil every 8,000 miles or so.

5 - 6 MPG -- Change your oil every 10,000 - 12,000 miles or so.

6 - 7 MPG -- Change your oil every 12,000 - 15,000 miles or so.

7 - 8 MPG -- Change your oil every 15,000 - 18,000 miles or so.

8 - 9 MPG -- Change your oil every 18,000 - 22,000 miles or so.

above 9 MPG -- Change your oil every 22,000 - 28,000 miles or so.

Last but not least, if your fuel pump has more than 400k miles of run time on it, then it needs its guts replaced to prevent total engine destruction without any warning.