Cam replacement cm2350

[SemiSweet]

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?

[Coronado126]

Since you put a new cam in, the wear surface on it will be new, and that means all the measurements will more than likely be off.

I would skip checking lash and readjust all the valves to Cummins spec using the T handle torque wrench method listed on QuickServe. That is if you have that torque wrench.

I never noticed excess wear or noise on the fleet of 2250 and 2350s I maintained using this method but I would have to ask Rawze about that.

{part of post removed. Bad information}.

[SemiSweet]

Thanks, yes the overhead will surely be set as per the service manual. The way I worded my question is a bit confusing now that I read it again. What I was implying was the gear MESH (lash) between the cam gear and the cam idler gear.

[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.

========

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.

[SemiSweet]

Good information, thanks.

The cam gear/Cam idler mesh was in spec. before removing so good to know I can focus on getting the timing gear seated and torqued correctly.

Fuel pump head is coming off for inspection and rebuilding the air compressor head as well since I have good access at the moment and the coolant is drained. Also, while I am at it may as well drop the pan and shim the oil pump.

I am having so much fun working on this motor...Thankfully this is not my first line of income and the truck is paid for.

[Waterloo]

Don't waste your time rebuilding the air compressor, for a couple hundred more get a quality reman, I found a good one at FleetPride, Haldex Genuine Cummins reman in the USA. $900 at the time, just bring in your old one as the core deposit is around $600. And make sure you remove ALL of the fittings off of the old compressor.

The reason I say skip the new head rebuild, been there and done that, it lasted around 70,000 miles and I was putting on that new compressor. I would also install a new air dryer when you do the compressor, they have them reman or new, and the prices on most aren't much more than a new dryer cartridge.

[Rawze]

(12-10-2020 )Waterloo Wrote:  ... I would also install a new air dryer when you do the compressor, they have them reman or new, and the prices on most aren't much more than a new dryer cartridge.

Some places will not warranty the air compressor unless you also install a new air dryer unit to go with it. - At least, that is my own experience last time I purchased one.