LLY - Cracked piston

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
18,206
440
83
Phoenix Az
cant get to those bolts without taking the front cover off. its a very very slight chance a long enough boxed end wrench with the right angle can reach in there and get one but you will be looking blind and run the risk of dropping the wrench in there.

can you put a mic on the diameter? ill measure the cam pins on my old front gear when i get home.

fyi, the pin doesnt have to stay in the gear. its strictly there to align the reluctor correctly and the bolts do the rest. it may have just been on its way out and you didnt catch it?
 
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NevadaLLY

Adam B
Feb 24, 2019
305
27
28
Reno, NV
cant get to those bolts without taking the front cover off. its a very very slight chance a long enough boxed end wrench with the right angle can reach in there and get one but you will be looking blind and run the risk of dropping the wrench in there.

can you put a mic on the diameter? ill measure the cam pins on my old front gear when i get home.

fyi, the pin doesnt have to stay in the gear. its strictly there to align the reluctor correctly and the bolts do the rest. it may have just been on its way out and you didnt catch it?
I hope that’s the case - I can see a little scoring directionally on the pins which look like press in marks - very faint. I left my tools at the shop but see if I can get a measurement on it somehow. Would be great to compare as they visually look too small to be those pins but I’m not sure where else it could come from.
 

NevadaLLY

Adam B
Feb 24, 2019
305
27
28
Reno, NV
literally nothing else i can think of. all the dowels in these engines are hollow.
Good news, I got a scope in there and I can see at least 5 of the bolts still look seated. I couldn’t get a good angle to see the pins or the last bolt, but I think I saw at least 1. The angle of the camera was difficult to fish though the oil fill tube and around the CP3 gear and nut. I ended up taking the oil fill tube out to get better control. At least I know the bolts still look seated and the reluctor isn’t loose. The fact I couldn’t see a pin might mean this is one of them… still reviewing my videos and photos the pin I have looks smaller.
 

NevadaLLY

Adam B
Feb 24, 2019
305
27
28
Reno, NV
Good news, I got a scope in there and I can see at least 5 of the bolts still look seated. I couldn’t get a good angle to see the pins or the last bolt, but I think I saw at least 1. The angle of the camera was difficult to fish though the oil fill tube and around the CP3 gear and nut. I ended up taking the oil fill tube out to get better control. At least I know the bolts still look seated and the reluctor isn’t loose. The fact I couldn’t see a pin might mean this is one of them… still reviewing my videos and photos the pin I have looks smaller.
I also took the cam sensor out to look that way. The sensor is too close to the reluctor to do anything from a camera view. Now the trick to get that 10mm back in blind… ☠image.jpg
image.jpg
 

Bdsankey

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Feb 1, 2018
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There are no smaller pins inside the engine. The smallest pin I know of that is "removable" is the reluctor. If you're confident that's not it then your guess is as good as anyone's.
 

NevadaLLY

Adam B
Feb 24, 2019
305
27
28
Reno, NV
There are no smaller pins inside the engine. The smallest pin I know of that is "removable" is the reluctor. If you're confident that's not it then your guess is as good as anyone's.
Are there pins in any other oil based parts? Turbo (S475 or valley), oil cooler, valvetrain? I cant remember any in/around the valves/lifters/rockers. I don't think the turbo's have anything like this but I haven't torn these models down before.
 

Bdsankey

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Reread my comment.

I don't know where something that small would've come from other than the reluctor or possibly the pinned oil pump (which you stated is present). The other dowels inside the engine are hollow like @Chevy1925 stated. It's not part of a lifter, not an oil cooling nozzle part, nothing from the oil cooler, nothing I can think of from the valvetrain, certainly nothing from the turbo etc.
 
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NevadaLLY

Adam B
Feb 24, 2019
305
27
28
Reno, NV
Reread my comment.

I don't know where something that small would've come from other than the reluctor or possibly the pinned oil pump (which you stated is present). The other dowels inside the engine are hollow like @Chevy1925 stated. It's not part of a lifter, not an oil cooling nozzle part, nothing from the oil cooler, nothing I can think of from the valvetrain, certainly nothing from the turbo etc.
That's the same conclusion I have.... I'm really starting to think something got trapped in one of the oil galleys during the hot tank process at the machine shop (unrelated to my engine all together). As that pin is so small, it could have been blown into the block during that process and no one would be the wiser.
 

rcr1978

Member
Apr 1, 2007
771
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Spring Creek, NV
If it was in one of the oil galleys you would have worse issues :oops:. Guess you have two choices, tear it apart or go on about your day and hope for the best if there is no obvious reason not to. Did you cut the first filter open to see if there was any suprizes in there?
 

NevadaLLY

Adam B
Feb 24, 2019
305
27
28
Reno, NV
If it was in one of the oil galleys you would have worse issues :oops:. Guess you have two choices, tear it apart or go on about your day and hope for the best if there is no obvious reason not to. Did you cut the first filter open to see if there was any suprizes in there?
Plan right now is to go on about my day.... oil pressure is good, temps are good, injector balance rates are good, fuel press is good. I'm still getting a lot of smoke so tuning still needs to be calmed down. I'm having some blow by (I think normal) out of the PCV and a little haze at the oil filler cap. It doesn't blow off the oil fill tube or even really move around so I'm not concerned about compression being an issue at the moment. If I can't get tuning in line, I'll do a compression check just for peace of mind. Engine runs smooth and has plenty of power so my gut is that compression is good. I am running the lower CH pistons in the Mahle performance cast but the tuning should account for that. I was also on the loose end of the tolerance for my PH clearance and am running Grade A HG's. All this could be playing into the smoke issue.

I have the oil filters from change 1 and 2 - will be poking into them this week. I didn't have metal on either my oil pan drain plug or my oil cooler drain plug (except this damn pin!) so I don't suspect any issues there either. It's really this pin that has be wondering what the hell it is and where it came from.
 

NevadaLLY

Adam B
Feb 24, 2019
305
27
28
Reno, NV
76D0F22B-7E2B-468C-AB37-D53445E26289.jpeg
well after scratching my head on the smoke problem for days now, I started poking around the exhaust side to double check. All the bolts were torqued to spec and none were loose by any means. However, I found an identical leak on both up pipes between the manifold and up pipe. These were new gaskets and they were the correct orientation and all bolts torqued correctly. In fact they were a pain in the a** to get back out even with antisieze I put on them during install. These pipes never leaked before… the gaskets were Mahle. I just picked up new GM oem which look a tiny bit thicker, but could just be crush depth. I’m puzzled why both would leak like this. No leaks at the turbo. Having so much smoke, the soot marks on my fresh clean block and heads helped me locate.
 

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
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Phoenix Az
ive always re-used factory up pipe gaskets if they are in good shape. Seen too many people have issues with aftermarket ones but i think someone was using a specific aftermarket gasket with real good luck. may have been @JoshH?

being you are on ppe cast manifolds and up pipes, if the stock gaskets go, you need to look into the flatness of the flanges. i seem to recall warping happening over time but dont take my word for it. It was from long ago when ppe split from buying profab
 

JoshH

Daggum farm truck
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Feb 14, 2007
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I've used the Mahle/Victor Reinz gaskets a bunch of times with no problems. I've also used the ProFab embossed gaskets and never had a problem with them leaking either. Lately I've been using factory gaskets because its so hard getting aftermarket gasket sets. The Mahle and factory gaskets I've used look identical to me, but I've never put anything on them to measure the thickness. The way that gasket is showing wear and leaking, it looks like it may be a flatness issue.
 

S Phinney

Active member
Aug 15, 2008
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Quncy, Fl
The noise you hear from the motor is three things. Too much rail pressure at idle, timing and probably will need some pilot pulse changes. LLY trucks have the loudest injectors of all version Duramax engines. My 200 overs I only have to run 42 Mia at idle to not have hazing. I have never had to run more than 45 MPa at idle in any one that I have tuned to date. One Mia us equal to approximately 145 psi for reference.


Sent from my iPhone using Tapatalk
 

NevadaLLY

Adam B
Feb 24, 2019
305
27
28
Reno, NV
I've used the Mahle/Victor Reinz gaskets a bunch of times with no problems. I've also used the ProFab embossed gaskets and never had a problem with them leaking either. Lately I've been using factory gaskets because its so hard getting aftermarket gasket sets. The Mahle and factory gaskets I've used look identical to me, but I've never put anything on them to measure the thickness. The way that gasket is showing wear and leaking, it looks like it may be a flatness issue.
Flatness potentially.. they were slightly “curved” before install but looked like a stack up normal thing to me. The new GM ones do a little of the same but not as severe. I’m wishing I kept the ones PPE sent and I had on as there were no leaks. Only replaced them because I was there and thought the Mahle would be great.
 

juddski88

Freedom Diesel
Jul 1, 2008
4,429
21
38
Chesterfield, Mass.
Flatness potentially.. they were slightly “curved” before install but looked like a stack up normal thing to me. The new GM ones do a little of the same but not as severe. I’m wishing I kept the ones PPE sent and I had on as there were no leaks. Only replaced them because I was there and thought the Mahle would be great.
He meant your flanges, not the gaskets
 

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