LS3 Engine Rebuild
Thread Starter
Instructor
Joined: May 2013
Posts: 184
Likes: 2
LS3 Engine Rebuild
Head
Piston
I just rebuilt my engine about a week ago and when I went to crank it, it started smoking. I thought it was old debris burning off first at first but the smoke never left. Afraid that I would damage the engine I tore the heads back off and discovered that I had oil pooled on top of the pistons on the passenger side. My head gasket was completely saturated with oil please see picks. I'm hoping that I just simply didn't line the head gasket up right but if I'm wrong I'm thinking it's the piston rings. Please take a look at the pics that I've attached and provide some advise of other possible issues.
Last edited by tobb14; Jan 13, 2019 at 03:51 PM. Reason: Add pics
Le Mans Master
Joined: Dec 2005
Posts: 6,999
Likes: 1,684
From: Southeast TX
Head
Piston
I just rebuilt my engine about a week ago and when I went to crank it, it started smoking. I thought it was old debris burning off first at first but the smoke never left. Afraid that I would damage the engine I tore the heads back off and discovered that I had oil pooled on top of the pistons on the passenger side. My head gasket was completely saturated with oil please see picks. I'm hoping that I just simply didn't line the head gasket up right but if I'm wrong I'm thinking it's the piston rings. Please take a look at the pics that I've attached and provide some advise of other possible issues.
Race Director
Joined: Aug 2005
Posts: 13,592
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From: Hudson WI
NCM Sinkhole Donor
The head gasket being saturated, in my opinion, confirms a head gasket issue,
Safety Car
Joined: May 2016
Posts: 4,641
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From: Erlanger, Kentucky
Probably head gasket problem.
The only other thing I can think of is the rocker arm bolts. Some LS3 heads need sealant on the rocker arm bolts as they can protrude into the intake runner but that is usually only on ported heads.
Other possibilities are valve guides and/or valve seals.
The only other thing I can think of is the rocker arm bolts. Some LS3 heads need sealant on the rocker arm bolts as they can protrude into the intake runner but that is usually only on ported heads.
Other possibilities are valve guides and/or valve seals.
Le Mans Master
Joined: Mar 2006
Posts: 5,775
Likes: 585
From: Texas
Probably head gasket problem.
The only other thing I can think of is the rocker arm bolts. Some LS3 heads need sealant on the rocker arm bolts as they can protrude into the intake runner but that is usually only on ported heads.
Other possibilities are valve guides and/or valve seals.
The only other thing I can think of is the rocker arm bolts. Some LS3 heads need sealant on the rocker arm bolts as they can protrude into the intake runner but that is usually only on ported heads.
Other possibilities are valve guides and/or valve seals.
Thread Starter
Instructor
Joined: May 2013
Posts: 184
Likes: 2
I was thinking valve seals as well. You did check the gap on all your rings, didn't you? And you did clock the gaps away from each other, right
Please explain in a little more detail about the valve seals. I did gap and clock gaps away from one another. I haven't herd about the seals, not sure how it plays a role
Please explain in a little more detail about the valve seals. I did gap and clock gaps away from one another. I haven't herd about the seals, not sure how it plays a role
Safety Car
Joined: May 2016
Posts: 4,641
Likes: 1,823
From: Erlanger, Kentucky
Interesting. Easy to check that then. Just look in the intake ports of that head and see if there are any holes. If there are they need a sealant on the threads when you install the rocker arms.
That may be the problem but it may not be.
Out of curiosity what head bolts are you using? Factory or ARP?
That may be the problem but it may not be.
Out of curiosity what head bolts are you using? Factory or ARP?
Last edited by Spaceme1117; Jan 14, 2019 at 07:56 PM.
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Safety Car
Joined: May 2016
Posts: 4,641
Likes: 1,823
From: Erlanger, Kentucky
The valve seals go onto the valve under the spring. They are an oil seal to prevent oil getting past the guides into the cylinders. They are usually pretty cheap and are very easy to change. It’s never a bad idea to replace them during a rebuild or when you change valve springs. One of those “while you are in there” kind of things.
If I were you, I would replace the valve seals, check both the heads and the block for flatness, put a fresh set of GM MLS head gaskets, and go with ARP head bolts or even better ARP head studs. And make sure to use a sealant on the rocker arm bolts.
If I were you, I would replace the valve seals, check both the heads and the block for flatness, put a fresh set of GM MLS head gaskets, and go with ARP head bolts or even better ARP head studs. And make sure to use a sealant on the rocker arm bolts.
Thread Starter
Instructor
Joined: May 2013
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hey thanks for the input but during the rebuild I picked up a cam kit with the new cam. Springs, push rods, valve seals and ARP everything from bottom end to the top were all brand new. I ported the heads and I'm hoping oil got by through the rocker bolts and if that's the case, the only thing I need is some sealant. Fingers crossed. I would be pissed if I have to tear the engine down again. That would really suck! I will replace the head gasket and put sealant on the rocker arm bolts. If that doesn't work then I will have to tear down the engine again.
Le Mans Master
Joined: Apr 2013
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hey thanks for the input but during the rebuild I picked up a cam kit with the new cam. Springs, push rods, valve seals and ARP everything from bottom end to the top were all brand new. I ported the heads and I'm hoping oil got by through the rocker bolts and if that's the case, the only thing I need is some sealant. Fingers crossed. I would be pissed if I have to tear the engine down again. That would really suck! I will replace the head gasket and put sealant on the rocker arm bolts. If that doesn't work then I will have to tear down the engine again.