Help on LS6 trouble
#1
On The Tree
Thread Starter
iTrader: (2)
Join Date: Feb 2006
Posts: 118
Likes: 0
Received 0 Likes
on
0 Posts
Help on LS6 trouble
I had my vette dyno'd on saturday and it put down 505hp/430tq but on the last pull it started a ticking sound after they let off. It sounded like upper engine noise and it was similar to a valve train tick that I am familiar with. Unfortunately , after I pulled the valve covers, I found no valvetrain damage, the springs are still one piece and the rockers/pushrods are all tight and undamaged. However, my oil changed to milkshake.
I was thinking of pulling spark plugs next to look for a specific cylinder with a bad (wet) plug? Also since this is my first LS motor I have opened up, any particular ideas that would cause the noise? It is too high pitched for a lower-end knock. When I drove it home the 30 miles from the dyno shop, the tick went away at about 2000-2500 rpm if that matters at all?
I also suppose a compression test would not be a bad idea?
I was thinking of pulling spark plugs next to look for a specific cylinder with a bad (wet) plug? Also since this is my first LS motor I have opened up, any particular ideas that would cause the noise? It is too high pitched for a lower-end knock. When I drove it home the 30 miles from the dyno shop, the tick went away at about 2000-2500 rpm if that matters at all?
I also suppose a compression test would not be a bad idea?
#2
TECH Fanatic
iTrader: (16)
Join Date: Aug 2006
Location: Internet
Posts: 1,078
Likes: 0
Received 0 Likes
on
0 Posts
I had my vette dyno'd on saturday and it put down 505hp/430tq but on the last pull it started a ticking sound after they let off. It sounded like upper engine noise and it was similar to a valve train tick that I am familiar with. Unfortunately , after I pulled the valve covers, I found no valvetrain damage, the springs are still one piece and the rockers/pushrods are all tight and undamaged. However, my oil changed to milkshake.
I was thinking of pulling spark plugs next to look for a specific cylinder with a bad (wet) plug? Also since this is my first LS motor I have opened up, any particular ideas that would cause the noise? It is too high pitched for a lower-end knock. When I drove it home the 30 miles from the dyno shop, the tick went away at about 2000-2500 rpm if that matters at all?
I also suppose a compression test would not be a bad idea?
I was thinking of pulling spark plugs next to look for a specific cylinder with a bad (wet) plug? Also since this is my first LS motor I have opened up, any particular ideas that would cause the noise? It is too high pitched for a lower-end knock. When I drove it home the 30 miles from the dyno shop, the tick went away at about 2000-2500 rpm if that matters at all?
I also suppose a compression test would not be a bad idea?
#4
On The Tree
Thread Starter
iTrader: (2)
Join Date: Feb 2006
Posts: 118
Likes: 0
Received 0 Likes
on
0 Posts
I understand a coolant tester will detect exhaust gas in the coolant but would a compression test be better to narrow down which cylinder it is if the spark plugs don't or do indicate as well?
#5
On The Tree
Thread Starter
iTrader: (2)
Join Date: Feb 2006
Posts: 118
Likes: 0
Received 0 Likes
on
0 Posts
On other news, I pulled the plugs and cylinder #7 looked grimey and wet, no doubt this is the cylinder with the head gasket breach.
I went ahead and skipped all the tests and started tearing down the motor. I got the intake off today along with the valvetrain and loosened all the exhaust manifold bolts.
I have the vortech supercharger and I need to look at the instructions on how this dumb bracket is best removed from the drivers side head.
Lastly, Since the passenger plugs looked all normal, should I bother switching out that head gasket as well or is this drivers side head gasket blowing out potentially a fluke? If I have to pull both heads I might as well look at swapping to 317 heads with LS9 gaskets, eh? If I can just get away safely with removing and replacing the drivers side head gasket only, that will save me a lot of time and a bit of money, but mostly time.
I went ahead and skipped all the tests and started tearing down the motor. I got the intake off today along with the valvetrain and loosened all the exhaust manifold bolts.
I have the vortech supercharger and I need to look at the instructions on how this dumb bracket is best removed from the drivers side head.
Lastly, Since the passenger plugs looked all normal, should I bother switching out that head gasket as well or is this drivers side head gasket blowing out potentially a fluke? If I have to pull both heads I might as well look at swapping to 317 heads with LS9 gaskets, eh? If I can just get away safely with removing and replacing the drivers side head gasket only, that will save me a lot of time and a bit of money, but mostly time.
#6
TECH Resident
iTrader: (1)
This engine passed a compression test.
Lastly, Since the passenger plugs looked all normal, should I bother switching out that head gasket as well or is this drivers side head gasket blowing out potentially a fluke? If I have to pull both heads I might as well look at swapping to 317 heads with LS9 gaskets, eh? If I can just get away safely with removing and replacing the drivers side head gasket only, that will save me a lot of time and a bit of money, but mostly time.
Trending Topics
#9
On The Tree
Thread Starter
iTrader: (2)
Join Date: Feb 2006
Posts: 118
Likes: 0
Received 0 Likes
on
0 Posts
I think I am going for a stock rebuild and have the tune looked over. My tuner said the afr was perfect. The timing showed no detonation but the max retard was moved from -10 to -3 degrees.
He also mentioned that it appears my duty cycle was at 100% and my MAF was maxed as well.
Any input on this information? Could the maxed duty cycle and maxed maf give false information and somehow cause detonation without knock sensors picking it up?
It appears my intake is bent as well. I removed the spring and spinning the valve by hand I can see a slight wobble to it against the valve seat.
The drill method looked fine on the intake valve. The exhaust valve had an obvious wobble to the naked eye and even more so on the drill.
Both will get replaced as well.