Luck of the draw.

I bought a very good condition anniversary Z06 in electron blue. It's a beast of a car and shall return to that glory. But for now, two days after registering it and just beginning to get to know the car and how it is set up I was stranded.

Putting part time into it over two nights I finally discovered tonight that the #6 exhaust valve lifter appears to have failed. By hand, I was able to tip the rocker back maybe a 1/4 to 1/2 inch off the top of the spring before hitting the pushrod. Pulling the rod out, it appears to still be fully straight. Rolling it on a granite counter, it had no wobble.

Walk me through next steps, if you will, to make sure I'm jumping in the right direction.

When I was stranded, what happened is that I left a light to turn right onto a ramp in traffic. The car began to clunk, cyclical with rpm, but seemingly not in direct correlation to rpm.... so a single lifter failure now makes sense. I immediately shut the car off and had it towed home, where I did turn it on for all of 3 seconds again to bump it quickly up into the garage. (No help pushing) I checked the plugs - all seemed good, but a little rich on #6. I opened the valve covers and checked rockers, springs rods etc visually. No damage, breakage, no pieces of metal or any flakes. I checked and changed the oil. Again, no parts, no metal or flakes etc. I went back tonight finally to play with the rods and turn to check for bends and when I got to the passenger side I realized the several of the rockers are, compared to the driver side, loose. At rest (no opening sequence on a given cylinder) two or three of the rockers can, if pressed, ever so slightly unseat their pushrod. It remains localized, just not firmly pressed in. But exhaust on #6 was different. I spun it in place fine and realized when I checked the rocker that it had a MILE of play.

SO - tomorrow I will pull the intake and check the valley. I haven't built an engine in 20 years - just bolt-on projects mostly - but I presume with the LS6 that pulling the cover will give me visual and physical access to the lifters, right? Or do I need to pull the head? I'm REALLY hoping I don't need to pull the head. I presume the lifter has failed / collapsed. When I placed the pushrod back in and tried to press in, there was no give on the lifter end.

Overall, I could kick myself now. I thought I heard a heavier tick in the idle, but I chalked it up to aftermarket valvetrain, a big cam, and the typical sewing machine LS sounds. This also makes more sense to me now how the car had such HORRIBLE time trying to idle and wanting to stall out. I bought it in a poor state of tune, uncompleted. Day 2 I had not yet looked at what's on the ECM and presumed, since it had been done by e-mail, that it was just a junk tune or hard to do by distance with EFI Live.

My general thoughts are that the lifter has likely failed. It may have gouged the cam lobe to hell. Maybe it didn't. I expect I will probably have to replace the cam and that opens up a whole can of worms trying to figure out which cam to go with and how I want to build the car - decisions I have not made yet.

My PRIMARY CONCERN is ensuring that the rest of the engine is not at risk of being skunked.

Existing longblock parts:
LS6 shortblock
PRC 225 heads
PAC dual springs
Tick Polluter v2 cam
LS6 rockers
Texas Speed pushrods
lifters unknown - likely Texas Speed?

This raises questions of product trust. I have used BTR and Straub on my current blown 99 coupe and the car is flawless. Can I trust the parts on this car and replace what has failed? Or do I scrap the PAC / TSP parts and go with what I know?

Any guidance from experience you guys can offer is much appreciated.



1,3,5,7 are left top to bottom. 2,4,6,8 are right top to bottom. And a fresh BR7ef replacement at the bottom for these tired TR6's.

 

Are you sure it's not a bent/broken pushrod? First thing I'd do, is pull that rocker and inspect both it, and the pushrod....

 

Yeah, above I say I pulled it and rolled it on a granite counter top. No wobble. Since granite is cut and polished smooth, it is the truest surface you could look for. For the rocker to have as much travel as it did, the pushrod would have to be very visibly bent.

I am thinking that because the valve lash may not have been set correctly, the pushrod has been slapping home at both ends having just enough travel to do so but to stay on the rocker. With this extra abuse, the lifter appears to have finally collapsed. This would make sense why I took the car in and it would not even hold idle. That cylinder was not operating as efficiently or correctly as the others. Oddly, that issue would reduce as the car got warmer.

 

You can see a few of the lifters with the intake and valley cover off, not enough to really inspect. The heads have to come off to change them out

 

Consider changing all the lifters. Is it possible the pushrod length is incorrect? How long has the engine been running after mods (before you bought it)?

 

Gotcha', apparently I skipped over that.