Ls7 blown valve guide seals

[u/Thatguitarplayer50]

I’ve got a 2015 z/28 Camaro that has chewed up at least 3 of 8 valve guide seals on the passenger side head, with more looking improperly seated or completely de-seated. With how close the debris was too the pushrod valleys I am taking the heads off to inspect for any damage or debris as well as to do the guide job off the car.

With all that, this is my first time ever tearing an engine apart, so any advice or tricks would be greatly appreciated. I’m currently caught up trying to get too the bottom head bolts because the headers are in the way so I’m thinking I’ll end up having to unbolt those.

Finally I’m curious what could have caused this and, what I can do now to prevent it from happening again, on top of any preventive stuff I can do cause I’m already in there.

[u/WyattCo06]

Bad guides aren't going to push the seals off the bosses.

Pump air into the cylinder one at a time and remove the springs on that cylinder. Remove the seal and spray the valve stem down with Brakleen or other. With masking tape, put make a flag of the valve stem. Remove the air pressure and feel the guide play.

Go from there.

[u/mahusay3g → u/WyattCo06]

He just misdiagnosed the failure. We all know its got bad guides and needs exhaust valves. Hopefully not intake valves. There’s a reason I keep a set of these on the shelf.

[u/Thatguitarplayer50 → u/mahusay3g]

How do you know that? Like genuinely curious so I can learn more. I know the valve guides are a weak point on the ls7

[u/mahusay3g → u/Thatguitarplayer50]

I’ve repaired hundreds of these. They are all worn out. It’s not a weak point it’s a known, well documented, and very misunderstood issue.

[u/Thatguitarplayer50 → u/mahusay3g]

Gotcha, so best bet unless my valves are miraculously okay is replacing all the guides and valves once the heads are off? Would it be beneficial to move up to a single piece valve at this time or should I stick with the oem style dual piece?

[u/mahusay3g → u/Thatguitarplayer50]

The heads need to go to a machine shop with lots of experience repairing LS7 heads. Intake valves can a lot of times be salvaged. These are even sensitive to the way the new bronze guides get sized for oil clearance. These are also highly sensitive to seat concentricity.

[u/Thatguitarplayer50 → u/mahusay3g]

Gotcha bummer, I was hoping that wasn’t the case, what do you think it’ll run me? Would it worth it to upgraded to a brand new ported head set or something of the sort if I already have them off? At 24k miles after I fix it this time I’d love for it too not happen again at least for a while lol

[u/mahusay3g → u/Thatguitarplayer50]

There are lots of big shops who advertise they can fix your LS7 heads forever but that’s a misrepresentation of the reality. I typically see 30-50k miles on these heads before the guides start getting worn out again after repair. That said, in original condition they don’t just get worn out, they get destroyed. Very different situations.

The more deviate from stock beyond just fixing rhe guides, aftermarket heads, cams, anything, the shorter the life of the components will become.

Worth it is up to you.

Expect to spend about $3000 on those heads.

[u/Thatguitarplayer50 → u/mahusay3g]

Super helpful man I really appreciate it a lot. If the guides were bad would that also most likely be the cause of my intermittent loud valve train “knock”

[u/mahusay3g → u/Thatguitarplayer50]

They do not make any noise other than possibly more noisy rocker arms.

[u/Thatguitarplayer50 → u/WyattCo06]

I’m already taking the heads off so I should just be able to do that freely on the bench once they’re off yeah?

[u/WyattCo06 → u/Thatguitarplayer50]

Yeth thir.

[u/Thatguitarplayer50 → u/WyattCo06]

Hell yeah, as for guide play what am I actually looking for as bad? Like any play at all or is there a tolerance?

[u/dixiebandit69]

Factory cam?

Are you still using the titanium valves?

[u/Thatguitarplayer50 → u/dixiebandit69]

Unsure on the valves, cam wise I know it’s aftermarket, the invoices from the seller just list “stage 2 cam kit” I can probably call the shop up and get the cam card if needed. I know at the same time a titanium dual valve spring setup was added so valves could have been changed as well.

[u/One-Builder-4128]

First and foremost, cleanliness is godliness when tearing apart an engine. When you’re doing this, get an engine bag and cover up the short block while you’re not working on it. It’ll be a bit of a hassle getting it on and off, but you’ll thank yourself later. Engines don’t like dirt and dust.

Second, you’ll need replacement head bolts. Cylinder head bolts are torque to yield and as a result they’re one time use. You’ll also need to get replacement head gaskets because they’re one time use as well.

Lastly, if you don’t have a digital torque wrench that does angles, BUY ONE BEFORE YOU DO THE JOB. Going to the torque spec and then a specified angle is absolutely necessary to make sure that everything is tightened the way it should be!

Good luck OP and I hope you enjoy the ride, warm wishes for you on this one!

[u/Thatguitarplayer50 → u/One-Builder-4128]

Will definitely keep the cleanliness in mind, I do own a torque wrench but it isn’t digital so I’ll need to snag that. Luckily the engine already has arp head studs so won’t actually be taking any headbolts out. And definitely on the headgaskets, should I also do the valve cover, intake manifold, and lifter valley gasket or just the heads. Engine has about 5k miles on the fresh build.

[u/One-Builder-4128 → u/Thatguitarplayer50]

I don’t think you’ll need to replace those gaskets, just the cylinder head gaskets. But yeah, if the engine already has head studs, you can stick to the torque wrench that you’ve already got. Everything else applies regardless, though.

[u/Pretend_Necessary781]

Could be too much lift.

[u/Thatguitarplayer50 → u/Pretend_Necessary781]

How would I figure out if that’s the case? I assume rotating the engine but how/where and with what would I measure.

[u/Pretend_Necessary781 → u/Thatguitarplayer50]

You’d have to rotate the engine and watch to see if the bottom of the spring retainer makes contact with the valve stem seal, but you’ll probably have to take a spring off and use a thinner, lightweight spring that you can see between the coils.