Generation V Internal Engine 2013-20xx LT1

What the hell is this?

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Old Mar 12, 2022 | 01:58 PM
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Default What the hell is this?

In removing the factory came I rotated the short block a few times on the stand.
One rotation I heard a tink-tink-tink and a little dowel fell on the floor!

What is it? Where do it pop out of?

It is 8mm in diameter and 12mm long - looks to be mild steel, not hardened.
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Old Mar 12, 2022 | 02:33 PM
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See if any head-to-block dowels are missing, though I thought they were tubular. Only other dowels are in the trans mounting face, directly across from each other a little ways from the oil pan mounting surface.
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Old Mar 12, 2022 | 04:14 PM
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mnnh - I am 99% sure I found the issue. They are much too small to be the trans locating dowels; those are 5/8" in diameter.

But your idea had me examine the oil pan rail itself, and there they were. evidently unlike earlier GM engines I worked with the pan is a structural part, and must be in a certain spot not located by screws.

That gives me the green light to proceed and button up the engine.
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Old Mar 12, 2022 | 06:07 PM
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The oil pan on all LS type engines IS a structural part. I wasn't aware dowels were used for the pan. Live and learn...
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Old Mar 12, 2022 | 06:14 PM
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Makes sense - the dowels locate the pan allowing looser tolerances on the bolt holes for quicker install.
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Old Mar 13, 2022 | 10:17 AM
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I’ve never encountered a pan on an LS platform that has dowels to locate the pan. Either aftermarket or OEM pans. You have to align the pan yourself, which is a critical step on putting the pan on. If pan alignment is off, you’ll have a bellhousing alignment issue. Oil pan is structural on the LS platform, in this regard.
Now…being as how this is Gen5 section, perhaps the Gen5 oil pans have the dowels? I haven’t messed with a Gen5 myself, so I can’t speak on that one.
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Old Mar 13, 2022 | 11:29 AM
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Originally Posted by Scarebird
In removing the factory came I rotated the short block a few times on the stand.
One rotation I heard a tink-tink-tink and a little dowel fell on the floor!

What is it? Where do it pop out of?

It is 8mm in diameter and 12mm long - looks to be mild steel, not hardened.

Is it the pin that's in the back of the crankshaft seen in this picture? After some further reading it looks as though Gen V LT's have camshaft dowel pins.

Last edited by 01CamaroSSTx; Mar 13, 2022 at 11:59 AM.
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Old Mar 13, 2022 | 08:14 PM
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Got a pic comparing the 2 pans, note where the pins go.

As stated, this is a simple and quick way to maintain positional accuracy yet allow quick assemble - think 2014-18 oil pump v. 2019 and up.

Holley Gen V pan on the right.

Crank has 8 bolts, and only goes on one way, ala Pontiac Strato V8 and others.



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Old Apr 5, 2022 | 06:30 PM
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Can one of you smart guys PLEASE explain to me why on the Gen III & IV engines there are no dowel pins for the oil pan/ timing cover/ rear cover?

"OIL PAN ALIGNMENT/ TORQUE CRITICAL" is literally cast into the pans on those engines, but GM didn't add dowel pins to anything.

Whenever I ask this question, I get crickets chirping.

They finally did it for Gen V, but why not for the previous generations? It's not an expensive addition, and almost every other manufacturer uses them.
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Old Apr 5, 2022 | 07:14 PM
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Old Apr 5, 2022 | 07:23 PM
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I’ll give it a go…oil pan alignment is super critical, as you said. But it’s also super easy to do with a straight edge on the back of the block. There are lots of guys that miss the alignment deal and really louse things up, even cracking their bellhousing on install, because they missed the alignment step. It’s just that however, a very important step. Every bit as important as setting up lifter preload, etc. Now as to WHY GM didn’t put the dowels in the Gen1/2/3/4 engines? I believe that they figured that experienced folks would be taking the pans off and on, or at least folks with common sense, or mechanical fortitude. I mean, they stamped it on most pans, as you mentioned. For me, it’s kinda like how our culture has evolved through the years. For instance….70 years ago, a cars owners manual would explain to you in detail on how to adjust the valve lash, and what tools to use while doing so. Todays owners manuals tell you to not drink the battery acid.
The Gen5 dowels take the setup and adjustment out of the equation, for likely the same principles. GM realized that our culture is going away from actually having to think for themselves, or to have any mechanical know-how involving this simple yet important step. That’s my take on it…
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Old Apr 5, 2022 | 07:26 PM
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Nailed it, Scott!
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Old Apr 5, 2022 | 07:41 PM
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Blaming it on the kids is kinda weak here.

We have first hand experience with old mechanics who can't be told a damn thing - let alone info literally cast in as to how to install the pump correctly. One of our criteria in our brake stuff is to try to make it idiot-proof as possible, but there are some who refuse to read the guide as they have been wrenching 40+ years quack quack quack...

I bet GM got tired of warranty claims and put the pins in so dealership mechanics can't **** it up.
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Old Apr 5, 2022 | 08:35 PM
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Originally Posted by Scarebird
Blaming it on the kids is kinda weak here.

We have first hand experience with old mechanics who can't be told a damn thing - let alone info literally cast in as to how to install the pump correctly. One of our criteria in our brake stuff is to try to make it idiot-proof as possible, but there are some who refuse to read the guide as they have been wrenching 40+ years quack quack quack...

I bet GM got tired of warranty claims and put the pins in so dealership mechanics can't **** it up.
Every dealership service bay I’ve been in during the past 10 years was nothing but kids working there…jus sayin.
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Old Apr 6, 2022 | 08:36 AM
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Originally Posted by Che70velle
Every dealership service bay I’ve been in during the past 10 years was nothing but kids working there…jus sayin.
True, in the last decade or so there has been a shift.

Last edited by Scarebird; Apr 6, 2022 at 09:23 AM.
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Old Apr 10, 2022 | 06:21 PM
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80 % of those kids starve to death working flat rate because of no common sense. I've worked with them, if the book said to stand on your head before putting this bolt in, that's what they would do. I had one that was given a fuel pump job, it took him 9 1/2 hours but only paid 3. I could put one in in less than an hour. Most of them can't think ahead and end up doing 3 times the work.
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