L5P will barely start, then die Please Help

[NC-smokinlmm]

L5p lifter failure

Wondering if any of you l5p gurus have some failure analysis input for me.So this truck came to me with a miss on one cylinder and a pop out of the intake,pulled the valve cover and found the valve lash extremely loose across the board,so loose one of the valve bridges had come out.Tore the...

www.duramaxdiesels.com

 

[JoshH]

The keyway on the cam won't cause a cam/crank correlation code because the sensor reads the gear rather than the cam itself. It can't see the position of the cam has moved in relation to the gear. It can cause cam timing issues, but it won't set a code. The code that is set says the cam and crank are more than +/- 10 degrees out of time. The reluctor wheel on the crank can't really move on these motors like they could on the earlier motors which makes me thing there's something going on with the cam especially since it was worked on after the accident, and you're having problems that sound like valvetrain related issues. What's really odd about it is how the popping noise is intermittent.

 

[Rdomeck]

I would agree that the intermittent is odd. I only first heard it on this last start up after having the DOC of the back of the engine. I'm also getting compression readings above the minimum required by GM.

I did see lower fuel rail pressures when the idle was above 700 leading me to believe that the high fuel rail pressure is the ECM trying to overcome the bad running.

What does the mm3 reading tell you guys?

I have verified from my old cam gear and reluctor ring that it can only go on one way. I can see readings from both the cam and the crank sensors. What else can I verify to prove those are reading and reading correctly? I do believe chasing down that code would be smart, but I'm at a loss of what else to check.

I do really appreciate all the input. I am learning a lot about this thing.

 

[JoshH]

Are you 100% certain the gear on the crank did not spin?

 

[Rdomeck]

I am 100% certain of that. I had the oil/water pump drive gear off. I could see the pin sticking up in the slot on the crank timing gear.....

But I just looked at photos and this looks suspect to me. I know I looked hard at this, but I did not pull the timing gears off.

Looks like I need to dig back in to the front of the engine.

 

[JoshH]

Yeah, something definitely looks off there.

 

[JoshH]

The easiest way to tell if the gear has spun is make sure the key slot in the gear is still in line with the pin for the balancer.

 

[Rdomeck]

The bad thing? I noticed this when I first did the repair. I thought it was supposed to be this way. The good news is that it hasn't moved anymore. I'm optimistic that I have no bent valves.

Now to figure out how to get this gear off with a sheared pin in place.

 

[2004LB7]

That doesn't look right

 

[NC-smokinlmm]

Damit…

 

[Rdomeck]

I can not get this gear off. I have about .045" behind the gear and the block. I made a puller, but not able to get this gear to budge. I'm either going to cut it off carefully or weld some bolts to the front of it and pull against those.

 

[Ron Nielson]

Heat it up, then pull.

 

[TheBac]

Well, at least you finally found the issue.

 

[Rdomeck]

So, what are my chances I have bent valves? I drove this with the crank gear in this position or very close to it. This does explain why it was very sluggish, but I didn't get on it much being a fresh build. I would guess that the cam is about 25-30° retarded.

I'll try some heat, then pull.

 

[2004LB7]

Drill and tap two holes opposite sides on the front and put all thread rods in them. Then with a plate with two holes in it at the end of the crank , tighten nuts on the all thread to pull it forward

 

[Rdomeck]

The gear is hardened. I already tried to drill and tap.

 

[2004LB7]

Instead of drilling. Maybe welding on nut couplers?

 

[Rdomeck]

I'll probably use some 5" long bolts and weld the head on the gear. Gives me more surface area. Then use a piece of angle with two holes. Let the angle touch the front of the crank and tighten nuts on the bolts.

Then apply some heat.

 

[JoshH]

You can get it off if you heat the gear. I've done it before.

Being that the valves are perpendicular to the piston, it is more likely that you bent push rods than bent valves if it was far enough out for valve to piston contact. I would pull the valve covers and check valve clearance before you put it all back together.

 

[Rdomeck]

Back together.... certainly have some noise in the heads. I'll pull valve covers to take a look.

I got lucky and the gear had stopped in a position that was at the right spot to skip 5 teeth.... So 40°. Not sure how it would even fire up. So, the crank gear is remarked and it is welded.

But, I have no codes shown!

I'll have a hard time believing it doesn't have bent valves. But only way to know is to dig in to it. Will probably do a compression test first. That will tell me if the valves are bent or not.