Help my silverado is eating my money

[calebhopper17]

Hey guys, I'm new to the site here, but i see you guys really help each other out and i need some wisdom.

I have a silverado with and LQ4 in it. This spring I found that 6 out of 12 exhaust manifold bolts were broken off and i had a wicked leak. I decide if i was gonna go through the trouble to drill out bolts i might as well treat myself to a set off edelbrock shorties. In the process of the unsuccessfull manifold removal I decided this was an opportune time to replace the heads and begin an engine build a couple parts at a time. I bought a set of Performer RPM Xtreme cylinder heads from edelbrock. Now with my new parts ready to go on I mounted my heads with mls gaskets and an ARP head bolt kit. I put my stock push rods and rocker arms back on reassemble the intake and made all proper connections and fired it up..... there was an incredible knocking that i took to be a couple flat lifters, so i tore it back down and replace all the lifters with parts from GM performance. I also check to make sure nothing else looked out of place. I reassambled again and there was no change. the lifters were workin fine and the knocking hadn't change. I'm stumped here and I would apreciate any and all input. thanks guys

[0rion]

Few questions....Are you soaking the lifters prior to installing them? Did you change the cam or is it the stock cam and check pushrod length? Rotate the engine as you torque down the rockers? Heads have bigger valves and did you verify piston to valve clearance? Stock thickness on the gaskets? Just some upfront questions to make sure you're not missing something basic.

[calebhopper17]

yeah i lube the lifters with comp cam lube. I rotated the engine while tightening the lifters. I checked piston to valve cleareance. I didn't check the push rod length, because i left the stock cam in, i figure it shouldn't change. am i mistaken on that?

[0rion]

but did you soak those lifters in oil prior to installing them?
if stock cam then pushrods should be fine but probably still should've checked them. From the sounds of it I'm thinking you didn't soak the lifters so they're not pumped up. Need to soak them for a couple of hours in oil...some say less but I made sure to give them a good soak.

[calebhopper17]

The pushrod length occured to me after i put in new lifters, but they don't have any slop in them so i didn't see how they could knock. I guess i'm not even sure how to check for proper length. I'm pretty new at this

[0rion]

if you're using the stock cam with stock base circle then the stock rods should be ok. You buy a pushrod length checker ( cheap) and use that to verify length. Not only could they be too short but they can be too long also and hold the valves open. I still feel like maybe you're not soaking those lifters in oil and that's your problem. So did you soak them in oil for a while? Have to get oil in those lifters so they pump up.

[calebhopper17]

The lifters were oiling through the tubes and everthing. I ran it for half an hour and they didn't quit knocking so I took the valve cover off and it was definitely pushing oil. can they be unprimed and still push oil up?

[calebhopper17]

I didn't soak them. I'll give that a try i guess.

[0rion]

let me move this thread to the internal section. Maybe I'm missing something that some of these guys have ran into. I would think in the length of time you ran it those lifters should've pumped up anyhow and if you're getting oil through the pushrods then that might not be your problem. Not sure how they act when you don't prime them.
With them not primed I'm also not sure what could've happened on that first start. I would imagine something was hitting something else somewhere.

[0rion]

did some quick reading and it seems the general consensus is it doesn't matter if you don't soak them as they'll pump anyhow. I've never not soaked them so I wasn't sure what would happen if you didn't. I'd move on to the pushrod length and verify that length.

[Hi-Po]

Stock cam correct?

Did you remove the cam?

Excuse my ignorance on those cylinder heads. Are they a stock casting that have been ported? Stock rockers? How did you install the rockers? TQ down to spec, then you should turn the motor over a few (4-5) times and recheck the TQ. The cheapest check you can do right now is to buy a pushrod checker. Have you been able to pin point the noise to any certain area? Also, I dont think it truely matters if you soak the lifters, but I would for peace of mind honestly.

[calebhopper17]

Yeah i torqued the rockers to spec. I have the haynes rebuild manual, and i've been doin things by the book, and they are stock rockers
The heads are all aluminum with partial cnc porting, and larger valves. I bought them from summit racing part number 61949
The noise is hard to track down location wise. it just sounds all over.
The push rod length is the only thing i haven't checked. They didn't seem loose and the valves weren't staying open, as when it ran it idled fine and ran normal other than the noise.

[Hi-Po]

Honestly, I dont think checking the pushrod length to going to help with stock base circle camshaft and rockers. But it cant hurt and is easy. I seriously doubt your having any PTV contact with that LQ4's dished piston even with larger valves.

[0rion]

Honestly, I dont think checking the pushrod length to going to help with stock base circle camshaft and rockers. But it cant hurt and is easy. I seriously doubt your having any PTV contact with that LQ4's dished piston even with larger valves.

that's kinda what I was thinking too but how close is it? What about the larger valves combined with the MLS gasket? He never said if that was stock thickness...what if it's a thinner gasket?

[Hi-Po]

that's kinda what I was thinking too but how close is it? What about the larger valves combined with the MLS gasket? He never said if that was stock thickness...what if it's a thinner gasket?

Even with a thinner gasket, I think it would be a long shot to have PTV problems. Not saying he shouldn't check PTV, that should have been done during installation. With my 57CC head, 230/236 .573 .578 camshaft and the LQ4's -8cc dished piston(IIRC), I had over .100" on both intake and exhaust if memory serves. Either way, my setup is going fine for 8,000 miles at least. I'm stumped on what this could be. I would ask for a video, but they hard to diagnose through video recorded sound, to me.

Everything to me seems like it should work, but there might be something being overlooked. How bad is the knock/noise OP?

[calebhopper17]

If there was piston to valve issues wouldn't i have a bent/broke pushrod or a nick in my piston or valve after running it for that long?
the steel gasket is a little thinner but like you said the stock cam is not aggressive at all.
191/190 0.457/0.466 I believe.
The noise is quiete loud. I'd describe it as a diesel noise, I ran it with the valve covers off(one at a time) and the noise didn't seem to be from the upper valvetrain.

[Hi-Po]

Hey guys, I'm new to the site here, but i see you guys really help each other out and i need some wisdom.

I have a silverado with and LQ4 in it. This spring I found that 6 out of 12 exhaust manifold bolts were broken off and i had a wicked leak. I decide if i was gonna go through the trouble to drill out bolts i might as well treat myself to a set off edelbrock shorties. In the process of the unsuccessfull manifold removal I decided this was an opportune time to replace the heads and begin an engine build a couple parts at a time. I bought a set of Performer RPM Xtreme cylinder heads from edelbrock. Now with my new parts ready to go on I mounted my heads with mls gaskets and an ARP head bolt kit. I put my stock push rods and rocker arms back on reassemble the intake and made all proper connections and fired it up..... there was an incredible knocking that i took to be a couple flat lifters, so i tore it back down and replace all the lifters with parts from GM performance. I also check to make sure nothing else looked out of place. I reassambled again and there was no change. the lifters were workin fine and the knocking hadn't change. I'm stumped here and I would apreciate any and all input. thanks guys

If there was piston to valve issues wouldn't i have a bent/broke pushrod or a nick in my piston or valve after running it for that long?
the steel gasket is a little thinner but like you said the stock cam is not aggressive at all.
191/190 0.457/0.466 I believe.
The noise is quiete loud. I'd describe it as a diesel noise, I ran it with the valve covers off(one at a time) and the noise didn't seem to be from the upper valvetrain.

Well, its something that was in this recent install, that we know. If you tore it down after the first time the noise was discovered and didn't see anything blatantly obvious then it doesn't seem to be the lower end either. Did this noise start right after you drilled out the broken manifold bolts? Nothing got dropped into cylinder right? Its not the aftermarket shorty headers banging on something is it? Compression test might be something to look into, then a leakdown test also. Just trying to give you other options then tearing it down yet again.

[calebhopper17]

I changed the heads because drilling out the bolts didn't work. nothing got dropped in.
The headers were fine too.
is it possible that the lifters were bad on the first install and when i ran it the cam was damage because of the heavier valve springs?

[joejenkinsglass]

Sounds like a bad exhaust leak to me. I'm going to assume you put oil in the engine.

[calebhopper17]

penzoil platnium full synthetic. and brand new exhaust gaskets, and headers torqued to spec