Ugh!!! Car popped!!! Bent valve or popped headgasket OR ??

[The Darkside]

While driving the GN home last night, I accelerated to get on the freeway & heard a slight pop, a quick puff of light colored smoke came into the cockpit through the dash, but quickly disappeared... The car sounded as if I either popped a headgasket, bent a valve or something???
Exited freeway & coasted(car still running) into a parking lot...
Observations:
Could hear a tapping noise from under the hood...Took a 3 ft piece of garden hose I had in my trunk & with one end up to my ear & the other searching for where the tapping noise was coming from, it seemed to be right in the top center of the drivers side valve cover. Tapping speeds up when I gave it more throttle.
Couldn't really hear any exhaust leaks when searching around the headers or head..
no smoke out exhaust
Oil looks nice & clean
oil pressure normal (25psi)
engine temps normal(175)
BLM's went from 125 to 142... ???
Shut the car off & had it trailered home by a friend...
This morning I pulled the drivers valve cover & took off the rockershaft looking for cracks, but it looked fine
Pulled the pushrods to check for straightness...they all looked good
I don't see any headgasket material coming out from around the mating surface...
Could be a bent valve or collapsed lifter? Maybe still a headgasket?? Someting else??

The Darkside

 

[Major Nutz]

A compression test will tell you if it is a blown headgasket. Mine did that wits a broken rocker.

 

[king kong]

From my experience....I'll bet that you blew the head gasket Everything you described is the sam exact symtoms i had when i blew mine on my WH1....A pop sound....and then some white smoke out tailpipe and in the car.....Then the light tapping sound, which you cant really figure out where its coming from...let me no what u find...I no the feeling...

 

[The Darkside]

Head is coming off by this weekend & I'll let you know what I find....

 

[king kong]

okay koOL Darkside

 

[king kong]

Just so you no Darkside.....A bad Alky pump caused mine to blow.....Not Julio's fault tho....Probably had a bad pump when i purchased the car....When Otto tested the pump it was barely workimg....i had no clue...Boosted the car, and Boom...Popped HG.....I should have had Otto check the car out before i boosted it, but at the time of purchase i did not know Otto

 

[blackgn1]

Why not do a leakdown test before the head comes off? A compression test will not always show a blown headgasket.

 

[The Darkside]

The alchy pump was just rebuilt by Julio a few months ago & has been working great.... According to the scanmaster, my o2's at the time of the pop were around 765, but what ever it went out with a bang, cause it showed up as 24 degrees of knock!!!!!

 

[king kong]

keep me posted on what you find

 

[Nick Micale]

Why not do a leakdown test before the head comes off? A compression test will not always show a blown headgasket.

A leakdown test will take 10 times as long as a compression test, but it will isolate a bad cylinder if it is a head gasket or a bad valve. The leak down test can more closely isolate a potential problem, but chances are the heads must come off before the exact damage can be determined.

If the head gasket did let go even a little bit, it WILL show low compression on one, or maybe 2 adjacent cylinders.

But you are right, with the rockers removed, a leak down test is now a no-brainer.

On a production turbo Buick V-6 engine, the head gasket is the "fuse" that saves it from more serious damage.

 

[Razor]

The alchy pump was just rebuilt by Julio a few months ago & has been working great.... According to the scanmaster, my o2's at the time of the pop were around 765, but what ever it went out with a bang, cause it showed up as 24 degrees of knock!!!!!

Typical head gasket stuff.. puff puff out the valve cover breather. And oil everywhere.
Broken rocker.. heavy ticking sound.

If you have oil out the breathers then its a HG. If not.. pull the plugs and do a quick compression check.

The old saying.. When you mess with the Bull... you get the horns.. Its part of racing an engine. Just need to figure out what part exactly and then why. Go from there.

Good luck.