Idle stumble when cold...And other stuff

[dhirocz]

Just came in from swapping my doser and turbo actuator. Got a few questions.

Actuator was installed with insite. New one works well. My VG ring has one hell of a notch in it but still moves OK otherwise. Was a good bit of soot under the actuator. I have a newer spare turbo that has a somewhat stiffer VG ring but moves smoothly. Would you swap it?

Replaced my doser...It was leaking coolant. I noticed I had NO fuel come out of the doser fuel line when I swapped it...Is that a sign of a faulty shut off valve?

Behind the Delta P there are two sensors on the block. The one at the top is leaking oil...And for whatever reason, I cannot find what it is. I'm assuming it an oil temp sensor...? I already changed the pressure sensor for the same thing.

Recently, the truck has developed somewhat of a stumble that resembles an intermittent misfire when warming up, at idle. When it's warm, I don't notice this. I have no codes right now. Insite is not failing any tests. During prime, I can hear what sounds like the lift pump changing pitch like the load through the pump is changing. I also hear a change of pitch at the moment it stumbles though I'm not sure that's where it's coming from. Lift pump puts out 26 while pumping, holds 14 with the key on, engine/pump off. FRP at idle is 250. I have not monitored any fuel pressure fluctuations during the stumble, but it's very brief and insite might not be refreshing fast enough to pick it up.

I plan on pulling the actuators and cleaning/inspecting them next, but could that pump cause that? As far as I'm aware the gear pump and lift pump are original.

2010 CM871 685k miles

[Rawze]

do an injector leak test ...




If the VG is hard to move, it is bad. If there is a catch in it, it is bad. Both will wear out your new turbo actuator prematurely running it like that. Go to a stealership and ask to see a turbo. Compare the movement with the new one to get a feel for how it should be.

The 2 connectors behind the delta-p sensor are the cam position sensor and the engine brake harness. They will only leak if you have high crank case pressure. Here is a solution that most people do to relieve this pressure...

http://rawze.com/forums/showthread.php?t...376#pid376

[dhirocz]

New turbo it is, then.
Interesting, I was actually thinking that my crankcase filter was about due and going to the maintenance free model so it can breathe better.

[dhirocz]

...This thing is gonna kill me. Called it early today since now I have a full ticking noise from the top end. Ex fleet trucks man, I swear. I'm about to go do a top end inspection now and see if I can locate this noise.

My truck sounds like a grandfather clock.

[Magard]

Check cam rollers I've heard it before.

[dhirocz]

Got a bearing failure on #1 exhaust. I'll finish disassembly tomorrow, clean out the oil passages and take a micrometer to them. I'll probably swap crossheads on that cylinder too, they've looked better.

Haven't noticed any damage on the cam. I think I might have caught it just in time. I'll take a closer look when the sun is out and the skeeters are gone.

[Rawze]

this may be of use...

The excess cam wear mystery revealed

[dhirocz]

OK so I need a new cam. Rocker was on its way out on #1 exhaust but hadn't scarred up the cam yet. But when I rolled the engine over, I found the same on the #5 intake...Which started to eat the cam.

With 685k on it I need to decide what direction to take. I'm fairly disappointed, seeing as I've made sure to change oil every 15k or less, have done multiple oil analysis done which all came back clean, run a filter mag, and run a bypass filter and this still happened. At least I caught it earlier rather than later. Had the truck since 607k.

Cam lost about .030" off the lobe.

If I decide to replace, I suppose I should plan for a new cam, rocker arms, drop and flush the pan, inspect/ replace the oil pump and replace the oil cooler...? I would also pull a couple caps and check the bearings while the pan was off.

[Nilao]

depending on your budget I'd consider a new head as well as cams. With that many miles your head is close to being worn out. I would also replace the rods and mains and do the harmonic balancer as its lifespan is 500k.