What are the signs of a blown head gasket
 

I done a compression check and it read lower on the whole passenger side (145-150psi) compared to the driver side (175-180 psi) its also making a loud tapping/knocking sound and I thought I heard some grinding noises to :eek2: I'm thinking the engine is done.I also pulled the valve covers off and didn't find anything visually wrong with the valvetrain
P.S. the car has 110,000 mi on it and it made the noise after a hard high speed nitrous run.Thanx in advance

Sounds like you may have torched either pistons or at least some valves. Signs of blown head gaskets are overfull overflow bottle or overflow out vent hose from hi pressure, coolant in your oil, external coolant leakage. Leak down test will diagnose your condition.

:judge: Hate'n the price of nitrous:bomb:

Yeah no shit it only takes a little mistake to mess things up :bang: :eek2:

If you're getting coolant into the engine, a scantool will tell the story. Look for LTFTs being off for one bank...the one w/ the cylinder swallowing antifreeze will have poisoned its O2 sensor and will think it's running rich. This causes LTFTs to drop into negative range, even tho the engine's really running lean.

So you're saying the LTFT's should be reasonably close to each other? I'm having a leakdown test done this month but because of your post I started looking at logs from September and October ( ATAP ). I see 2.1's on one bank, -1.6 on another, or else like 5.5 and 3.1. Is this within normal range?

While the guys have the plugs out for leakdown, make sure they inspect them for color variation. Cylinders eating coolant will have very clean plugs compared to the ones on the opposite bank.

Not sure what's normal for your particular engine, but removing the front O2 sensors for visual inspection would be a good next step given the variation.

If one sensor (the one for the bank w/ the negative LTFT) has white crystalline deposits on it, you have a winner.

Spun bearing: knocking, sounds like it's coming from the middle of the engine, higher pitched tapping then an old school SBC, oil pressure fluctuates at idle; metal in the oil

Blown headgasket: white sweet exhaust, chocolate milk in the valve covers, pressurize overflow, radiator is down 2-3 quarts when cold - It all is pretty obvious after an hour of this

Just changed all 8 last week, looked very good ( from comaring at http://www.densoiridium.com/howtoreadusedplugs.php ) with one being a HAIR whiter compared to the rest. The O2's look good as well , so hopefully I'm good. The leakdown will be the ultimate test.