I am not sure if this is a big issue yet. It is a costly fix.
My wallet does not like this one!!!

Mine sheared then took a couple of spins around the cam.
How about you?



WAIT............Where'd my wallet go!!!!!!!!!!!!!!!!!!!!!!

It's becoming more common every day. Eric has a fix for it and just recently Guy came out with a neat fix too. How much power are you running through your motor?

Nick

Just Edge. I run 30psi max. I tow with the truck every day on Level 1 and sometimes 2. I have a call in to Eric I'm waiting on a call back.

Looks like I'll be doing some engine repair, and might aswell do the tranny while its out.

Is this motor an "interferance motor"? Meaning, what all hits and destroys itself when the pin shears? I did a rebuild at 164k and mine looked fine. Seems these are like injectors, some go and some don't. I have had plenty of injectors though.

What kind of miles you have on it? I know this really does not play a factor, since Eric has a 505,000 miler with the cam pin looking AOK, but I am just courious...

148,000

Here are some pics
http://www.dieselplace.com/forum/showthread.php?t=140375&page=4

148,000

Here are some pics
http://www.dieselplace.com/forum/showthread.php?t=140375&page=4
:drop_mout Thats gotta hurt. Good luck on the build.

Is this motor an "interferance motor"? Meaning, what all hits and destroys itself when the pin shears? I did a rebuild at 164k and mine looked fine. Seems these are like injectors, some go and some don't. I have had plenty of injectors though.

The heads are basically flat in the combustion area, and the piston protrudes into the head gasket, so yes...its an interference motor.


I do not care what all the "experts" say....that little pin acts like the key, not just a "locator", and its the thing keeping the cam gear in the proper spot. Too darn much force acting on it, and its not up to the task. Doesn't matter how many ft/lbs of torque are on that darn bolt, it will not hold the cam gear in one spot against the rotational force.

I know I'm gonna get flamed hard for that, but thats what I believe.

My valves / heads appear to be ok, but they will be sent out and checked aswell.

As it looks now, I could extract the bolts and replace the retainer. Better safe than sorry though.

The heads are basically flat in the combustion area, and the piston protrudes into the head gasket, so yes...its an interference motor.


I do not care what all the "experts" say....that little pin acts like the key, not just a "locator", and its the thing keeping the cam gear in the proper spot. Too darn much force acting on it, and its not up to the task. Doesn't matter how many ft/lbs of torque are on that darn bolt, it will not hold the cam gear in one spot against the rotational force.

I know I'm gonna get flamed hard for that, but thats what I believe.
If you were wrong then the bolt should've prevented this from happening. I'd say your statement is fact.

At stock power levels the bolt in the camshaft does it's job just fine, and the pin is a locater only for the cam gear. When you start upping the power the bolt can no longer do its job due to the changes in harmonics and vibrations generated in the engine so the pin begins to act like a drive key and it cannot take it, that's why it breaks! It was never intended to be a drive pin.

Has this ever happend to a stock truck?

Yes, or at least close.:(

90% of the time my truck see's Level's 1 and 2. Clearly less than hp ratings on the new motors with the same "pin". I don't see why this happend considering's it sees level 5 rarely.

My valves / heads appear to be ok, but they will be sent out and checked aswell.

By the looks of the pic with the piston, the valves came into contact. My motor looked the same way with the valve marks on the piston. Heads and valves seemed ok, but ended up having 18 bent:eek: . I am sure you will find the same. Let me know if you need pushrods, I have a new OEM set that I did not use.

One quick question...why didnt you pull the motor? My back hurts looking at all that work:D

Doing that tomorrow. I have two bad disc's in my back. I'm lucky that I get done what I do in a day.

I wanted to see how bad it was before I made any decisions.

At stock power levels the bolt in the camshaft does it's job just fine, and the pin is a locater only for the cam gear. When you start upping the power the bolt can no longer do its job due to the changes in harmonics and vibrations generated in the engine so the pin begins to act like a drive key and it cannot take it, that's why it breaks! It was never intended to be a drive pin.

Sorry Steve, but I've seen stock cams at Merchant's with worn cam pins. The Isuzu engineers should have been intelligent enough to realize that pin would become a drive key, and should have machined the cam accordingly.....cost be damned. Heck, I'm not an engineer and I can see it.
+50hp isnt the root cause of it. Poor design is.

Sorry Steve, but I've seen stock cams at Merchant's with worn cam pins. The Isuzu engineers should have been intelligent enough to realize that pin would become a drive key, and should have machined the cam accordingly.....cost be damned. Heck, I'm not an engineer and I can see it.
+50hp isnt the root cause of it. Poor design is.

i agree, this is a more logical explanation to it, especially when you look into people running high hp on a stock motor without issues. its more "hit and miss" so to speak. hopefully more miss for the bulk of us though:D

i agree, this is a more logical explanation to it, especially when you look into people running high hp on a stock motor without issues. its more "hit and miss" so to speak. hopefully more miss for the bulk of us though:D

Amen to that. We do not need this to become our "Killer Dowel Pin" like some Dodge guys found in their Cummins.

Amen to that. We do not need this to become our "Killer Dowel Pin" like some Dodge guys found in their Cummins.

That is true, but Cummins did a redesign GM hasn't.
They can't admit that the LLY is a overheater why would they ever own up to the cam pin being anything other than what it really is, A piece of junk.

Merle

how is the rebuild coming?

Sorry Steve, but I've seen stock cams at Merchant's with worn cam pins. The Isuzu engineers should have been intelligent enough to realize that pin would become a drive key, and should have machined the cam accordingly.....cost be damned. Heck, I'm not an engineer and I can see it.
+50hp isnt the root cause of it. Poor design is.

If you look at the amount of failures of the camshaft pin in stock motors where nothing else has gone wrong in the engine the numbers are almost 0. All motor have some failures that's just part of life. That said it could always be better, you have to draw the line somewhere. This type design is nothing new nor is the Duramax the only engine to use it. The truck in this thread has an aftermarket turbo, exhaust and tuner so that's a far cry from stock anyway you cut it. If you plan to play you need to be ready to pay.

If you look at the amount of failures of the camshaft pin in stock motors where nothing else has gone wrong in the engine the numbers are almost 0. All motor have some failures that's just part of life. That said it could always be better, you have to draw the line somewhere. This type design is nothing new nor is the Duramax the only engine to use it. The truck in this thread has an aftermarket turbo, exhaust and tuner so that's a far cry from stock anyway you cut it. If you plan to play you need to be ready to pay.
With that being said what do you feel is the actual cause or should I ask do you think maybe making more hp and reving the motor quicker by which I mean the ability to reach peak hp or a given rpm quicker from the extra hp is causing strees to the cam pin? Hope I'm making sense with my question.

It is a NVH problem caused by many things not the least being the cylinder firing pressure pulses that get transmitted back into the camshaft nose where the pin is. Most people do not understand that and engine fires 1 cylinder and that puts a sudden forward motion into the crankshaft which in-turn does the same thing to the camshaft, then it begins to slow and then the next cylinder fires again. This sudden acceleration plays havoc on the parts and when you increase these pulses the jarring motion goes through the roof. The harmonic balancer is there to help soften/dampen the pulses at the stock power levels but that's what it was tuned for. When power is stepped up the tuning of the damping effect maybe all wrong in the balancer. From there you move on to effects of the valves opening and closing and those vibrations back into the camshaft nose/pin. One of the most common things is to raise the boost levels and again this changes the motion from the valve train which can have ill effects on the camshaft nose/pin. As you can begin to see many things all play into it and I cannot tell you which one causing it or it maybe all of them combined, but to say it's a bad design is just wrong. It does it's job at the power levels it was designed for and like I said you have to draw the line somewhere.

Makes sense to me. Definatly seeing high boost causing a valve to try and hang open longer than it's supposed to.

I luckly caught mine pin early before it could do any damage. I agree that a 5 cent pin should not be liable for $thousand in possible damages.

From the info here I just joined the club. 02 66,000 miles all stock
Well my warrenty was up on 11-26-06 so im a little upset right now. I guess I'll contact GM to see if there is any good will floating around.I called thelocal dealership fri ,first question did you buy it here. I guess this is a test to see if I can stay smoke free, 5 months so far.