Is my engine shot?
Safety Car
Joined: Mar 2016
Posts: 3,534
Likes: 432
From: Atlantic Beach FL.
I'm not sure if you understand how the PCV is supposed to work but it is fairly simple. When the engine is running there is combustion pressure in the cylinder. A small amount of pressure makes it past the piston rings and builds up in the crank case. If the gas isn't vented then it will find it's way through the seals or gaskets. Back in the day they would just put a breather cap on the valve cover. Now they feed it back into the intake where vacuum pulls it back into the engine to be burnt again. The valve protects the crank-case in case of backfire.
It your case you don't always have vacuum at the throttle body but at higher RPM's you actually have pressure. You don't want pressure getting into the crank case. You need a valve to keep that from happening. You can find a generic PCV valve that you can put into that line if you need it.
I would take the line coming from the valve cover and put it on the filter side of the supercharger so that when you have boost and the check valve closes the crank case gasses have another place to escape.
Hope this helps.
It your case you don't always have vacuum at the throttle body but at higher RPM's you actually have pressure. You don't want pressure getting into the crank case. You need a valve to keep that from happening. You can find a generic PCV valve that you can put into that line if you need it.
I would take the line coming from the valve cover and put it on the filter side of the supercharger so that when you have boost and the check valve closes the crank case gasses have another place to escape.
Hope this helps.
Last edited by Rob 02; Jun 9, 2017 at 12:02 PM.
Safety Car
Joined: Mar 2016
Posts: 3,534
Likes: 432
From: Atlantic Beach FL.
You may want to check compression. Even if it is bad news you may be able to salvage the block if you don't run it much more. If it is bad news then you could use it as an excuse to upgrade to a stroker with forged internals.
Thread Starter
Racer
Joined: Nov 2015
Posts: 408
Likes: 5
From: New York
Yeah I get the idea of the pcv but definitely do not completely understand it. This helps alot. So im gonna go from valve cover to the intake before the MAF and then from the valley cover to a check valve to the manifold?
Safety Car
Joined: Mar 2016
Posts: 3,534
Likes: 432
From: Atlantic Beach FL.
I pretty sure there is a check valve in the LS6 valley cover. If you can't blow air in it then there already is one.
I regret not using the LS6 valley cover when I assembled my engine so I don't know for sure if there is one in there.
I regret not using the LS6 valley cover when I assembled my engine so I don't know for sure if there is one in there.
Last edited by Rob 02; Jun 9, 2017 at 12:16 PM.
Thread Starter
Racer
Joined: Nov 2015
Posts: 408
Likes: 5
From: New York
So I took the T off and had the hose from passenger header go to an open ended catch can and then I had the hose from the valley cover just hanging out. At idle there was no smoke. Then when I hit the gas some smoke started coming out. Very very little oil if any this time. Now if I close the loop and have the hose from head go to one opening in catch can then the other end goi g to throttle body and the hose from valley go to manifold where does the excess pressure escape?
Thread Starter
Racer
Joined: Nov 2015
Posts: 408
Likes: 5
From: New York
So I used two catch cans and tested it out. One from valley cover to catch can and then from that can to check valve to intake manifold. Then a hose from head to vented can. Smoke coming out of vented can immediately.
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Burning Brakes
Joined: Jul 2011
Posts: 1,096
Likes: 110
From: Fredericksburg Virginia
Compression check # 7. I was pushing oil mist and smoke on mine and was missing oil control rings and second compression ring along with ringnlands between them. New motor runs much better and doesn't push dipstick out 
Chris
Chris
Thread Starter
Racer
Joined: Nov 2015
Posts: 408
Likes: 5
From: New York
Thanks. Tomorrow I'm gonna do a cylinder balance test with my hp tuners and see what that shows new then I'll go by a compression tester and do that as well. Really hope it's not a cylinder.
Thread Starter
Racer
Joined: Nov 2015
Posts: 408
Likes: 5
From: New York
Safety Car
Joined: Mar 2016
Posts: 3,534
Likes: 432
From: Atlantic Beach FL.
I don't know because the only way that I can think of smoke getting into the crank case is through the cylinder. An engine is pretty simple really. That is probably not good news.
When you do your test you may want to number the spark plugs and look at the wear and color of the deposits on the tip.
When you do your test you may want to number the spark plugs and look at the wear and color of the deposits on the tip.
Thread Starter
Racer
Joined: Nov 2015
Posts: 408
Likes: 5
From: New York
So finally yesterday i day I did a compression test and 4 cylinders were at 90psi. 2 were at 155ish and 2 around 170. Tried a wet test on one cylinder and no change. Not sure if I got enough oil in though. So I might buy a leakdown tester today and try that tonight. I'm hoping it's a head gasket
Safety Car
Joined: Mar 2016
Posts: 3,534
Likes: 432
From: Atlantic Beach FL.
I doubt you would have a cracked piston with four of them @ 50% and the wet test would rule out leaky rings.
I would only do a leak down test if the standard compression test measured good. You already know that the 90psi cylinders are not going to pass leak-down.
Unless you had an oil starvation issue or over revved the engine during a down-shift I wouldn't suspect bad cylinders or rings as the culprit.
I'm kind of thinking head gasket especially if all four of the bad measurements were on the same side. In that case I would assume that your cylinder pressure is so high that it stretched the head bolts enough to leak in winch case may have warped the head slightly. If you have to remove the head it would be a good idea to get some ARP head bolts or something stronger than stock.
If you disassemble the heads you can have them rebuilt by a competent shop for $150-$250. That would include valve and seat refacing (triple grind) and resurfacing the deck. At that point you may want to consider any other mods to the top end.
I would only do a leak down test if the standard compression test measured good. You already know that the 90psi cylinders are not going to pass leak-down.
Unless you had an oil starvation issue or over revved the engine during a down-shift I wouldn't suspect bad cylinders or rings as the culprit.
I'm kind of thinking head gasket especially if all four of the bad measurements were on the same side. In that case I would assume that your cylinder pressure is so high that it stretched the head bolts enough to leak in winch case may have warped the head slightly. If you have to remove the head it would be a good idea to get some ARP head bolts or something stronger than stock.
If you disassemble the heads you can have them rebuilt by a competent shop for $150-$250. That would include valve and seat refacing (triple grind) and resurfacing the deck. At that point you may want to consider any other mods to the top end.
Last edited by Rob 02; Jun 14, 2017 at 09:16 AM.
Thread Starter
Racer
Joined: Nov 2015
Posts: 408
Likes: 5
From: New York
Yeah I was hoping that I can just take the heads off and get them machined. The bad cylinders are on opposite sides of the engines but they are adjacent to each other making me think its the head gasket. I just hope that I dont do all that work and then it be pistons and have to rip it all apart and pull the engine again but it is a way cheaper option for now.
Not sure I understand what you mean the cylinder is high? How does that happen? I will begin taking the heads out tonight. At least I dont have to take the steering rack out again.
I will get them bored and replace everything in the heads if they are salvageable.
Thanks for all the help/.
Not sure I understand what you mean the cylinder is high? How does that happen? I will begin taking the heads out tonight. At least I dont have to take the steering rack out again.
I will get them bored and replace everything in the heads if they are salvageable.
Thanks for all the help/.
Safety Car
Joined: Mar 2016
Posts: 3,534
Likes: 432
From: Atlantic Beach FL.
"Not sure I understand what you mean the cylinder is high? How does that happen?"
Sorry, that was a typo. I meant cylinder pressure, from your performance mods.
As far as head porting. I wouldn't trust just any shop unless they have a lot of LS engine experience. You could do a search or start a new thread on that topic alone. I'm not sure what is best for supercharged engines as far as head work goes.
A little porting and polishing can't hurt flow though.
Sorry, that was a typo. I meant cylinder pressure, from your performance mods.
As far as head porting. I wouldn't trust just any shop unless they have a lot of LS engine experience. You could do a search or start a new thread on that topic alone. I'm not sure what is best for supercharged engines as far as head work goes.
A little porting and polishing can't hurt flow though.
Last edited by Rob 02; Jun 14, 2017 at 09:28 AM.