TraviZ

iTrader: (2)

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?

Empatho

iTrader: (16)

That is never a good sign

.boB

iTrader: (1)

That's a bad thing. Usually means a blown head gasket.

Go down to Autozone and borrow their coolant test kit. They'll charge you $80, but you get it back when you bring the kit back.

TraviZ

iTrader: (2)

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?

TraviZ

iTrader: (2)

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.

.boB

iTrader: (1)

Not really. Sometimes the leak only occurs under certain conditions, like when it's hot and cylinder pressures are high. Often a leak down test won't tell you anything.

This engine passed a compression test.



It depends on what you find when you pull the head off. It could a fluke, a cracked head, or even a bad gasket from the factory. Or, the other side is a ticking time bomb waiting to go off. You just need to figure out why that one went, and then decide what to do next.

TraviZ

iTrader: (2)

Thanks, I will post what I find when I get it off, hopefully tomorrow.

bbucropleyb

I got the intake off today along with the valvetrain and loosened all the exhaust manifold bolts.

TraviZ

iTrader: (2)

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.