Hey Ya'All
Need some help. I recently had my 2002 LS1 upgraded with Ported AI Heads, custom Cam, ported Fast 92 intake, NW TB, new LS7 litters, new springs, all new gaskets, etc... With three tunes to finally get her right by a reputable shop that is a sponsor here. Frustration to get her right, and to add to that, the First time I took her out to enjoy the new found power at a local autocross track (Roebling Road) she took a crap on me on my third run around the track. She started violently backfiring, and a pronounced ticking/clicking started coming from what appears to be under the drivers side (under the gas pedal) area. When I opened the hood at the track, there was a small amount of a white/clear spray under the hood. I was able to limp home with violent backfiring. Oil pressure and temp was fine, with no SES light on.
My mechanic friend with some engine knowledge opened her up to find that #5 and #7 plugs (new set of NGK55 plugs) were slammed shut wit no gap left! Hence the backfire. No debris in the cylinders, lifters, pushrods, springs all good. Only thing we can think of is violent combustion casing the gaps to close being that the plugs were too hot or the tune too rich? We changed the plugs to NGK6's tapped at .35, and she runs fine w/o backfire, and power seems fine and oil pressure at 40. Yet that loud clicking exists still. Clicks loud on idle from somewhere lower back driver side. If you rev her slightly in park, the clicking goes away. But in drive, the clicking is there and increases with increased engine RPMs. It is fairly loud, and lower than lifter or roller rocker knock....and since visual inspection is fine. There is no true coolant mixing in my oil, so with the fact that i just had a new head seal installed with rebuild upgrade I don't think it is a bad head gasket. The engine has only 60k on the block, and I didn't overheat at the track, so I can't imagine a cracked block. The only thing I can think of is a broken flex plate, or maybe insufficient oil to the back cylinders...maybe a failing oil pump? Exhaust seems tight, and header bolts are good...thinking that maybe I blew something loose on the exhaust with backfiring?

So, what do you think it is? What caused the plugs to be smashed? The tune could be too rich? It does real of gas and my gas mileage sucks now after all the upgrades....maybe too rich and too much combustion closed the gaps?

What is that clicking/clunking? A busted flex plate? Would that cause an increase in clicking as the engine revs go up? And not so much while revving in park vs in drive? Maybe not enough oil getting to the back cylindesrs.

With our limited shop tools and no lift, I'm leaning to take it to a transmission mechanic first.
1. Check Flexplate 2. Check oil pump,maybe upgrade to LS6 pump? 3. Busted bearing?

Anything else that you think it could be?

Thanks guys

 

Video would be great. Buy a stethoscope and try to trace it, see where is sounds louder.

 

Try to listen to the bottom closly and the top as well. See what sounds louder.

 

OP, you may check your O2 sensors, due to all the backfire's they may have blown out. I had that issue with my 5.3 about 32k miles ago when I blew a couple spark plugs romping through too much mud and water. Also, check the weld points on the exhaust, they may have cracked. Flex plate might also be a problem but you'd likely get more vibration than a ticking noise. Like mannyman84 said, go get a stethascope and try and pin point where the noise is coming from. Also, vids don't hurt, I'm sure a more experienced tech would love to see what the problem is on here.

 

You either sucked something into those cylinders OR you broke a few pistons. I would be using a inspection camera through spark plug holes to check for broken ring lands.

violent combustion AKA DETONATION causes BROKEN PISTONS....it doesn't close spark plug gaps. Broken piston pieces cause closed spark plug gap.

 

We tried the stethoscope thing, not on top end. Mechanic was pretty sure that the engine was good, but then again we didn't get down into her deep. I'll try and post a video of the tick. Darn loud tick at that. Would a flex plate cause that?

 

Did you pull the valve covers? Valve springs and rocker arms look good?

 

This. If those look good, I'd bite the bullet and pull the heads to inspect for damage.

 

You need to pull the heads. That is the only way to know for sure.

 

Pulled valve covers, all good on lifters, springs etc... He didn't want to pull the heads on likely chance it was the flex plate, as no power loss or oil pressure changes.

 

I'd definitely pull the heads just to make sure. Could have a bent pushrod in there.

The only thing I can think of is an injector dumping fuel or stuck open to damage/foul the plugs like that.

 

Here us the link for a video I made for the sound coming from inside the car, where it is really heard best. Loins clanking from lower drivers side, likely cyl#7. Could here it good inside the car and behind front driver side tire. Increases with RPM's. Any guesses?

https://i

 

Video aint werkin guy. I'm telling ya if the spark plug gap was closed the piston broken a ring land and as it exited the cylinder it whacked the plug. Number 7 cylinder is notorious for this.

 

I'd do a compression test on it.

 

Compression was good, I'm checking the lifters tomorrow. It sounds exactly like a 05 GTO with a bent lifter on YouTube. Like a hammer hitting metal, loud clank, clank, clank. Brand new hardened lifters were just installed, along with everything else on the top end was replaced...and the first time out, Kablam! Could they have been measured wrong when they were installed, and that inturn would cause it to bend? What bends a lifter, revs too high? Can too long of lifters help close the gap on the plug or make it a bitch to tune? They had to tune her three times tonged her not to stall out.

 

Here is the video link that should work

 

So what was it?

 

Diagnosed as a cracked block between cylinder 5 and 7 at water jackets, broken piston ring lands to go with it. They are thinking the head gasket went first, then the ring lands then the block. what makes no sense to me was that there was a new head gasket installed just two months prior when the heads and cam and tune were done. I never overheated the car before, nor during the beginners autocross session, learning the track where she blew. Thought a car with 60k miles and a new top end could handle 60-80mph turns for twenty minutes....guess not!
Time for a whole new engine block after dumping 5k into the old one that lasted two months and about 200 miles on it. The ported AI heads were salvaged and the custom AI cam along with the new springs, Manley rods, etc.. I'm going 383 Stroker with forged internals now.
Bum luck or what else would cause a block to crack? It makes no sense to me!

 

ouch

 

Guess you just learnt what oil surge is!
Fit an Accusump if you are going to continue autocross or road race.