Hey guys,
I recently had an issue with my LS6 that was in my 2002 C5 Z06.
I was told by a local "corvette expert" shop that at least 1 rocker arm was broken, and that there was a good chance my cam broke and did damage to the bottom end.

Fast forward 5 months to today. A brand new LS6 is completely installed in my z06 now and i have the old LS6 sitting in my garage on a nice engine mount. Ready to tinker away.

I removed the "broken" rocker arm last night and see that it's definitely not broken at all. However, the tension was lost on this one rocker arm because the pushrod and valve are not in sync to hold it tight. I am not an expert with motors but I'm wondering if maybe the cam is broken and because of that is no longer pushing on the push rod that holds the rocker arm in place? Does that even make sense?

I'm now wondering if this is as simple as replacing the cam to get this motor back to where it should be.

For what it's worth, here are the list of mods on this motor we are discussing:
-World Warhawk LS1X aluminum heads (11:1 / 62cc chambers / 235mm runners) (135lb on seat / 390lb open pressure)
-REV SS valves (2.08 intake / 1.6 exhaust / 45deg seat / 30deg back angle cut)
-REV Vanadi-Coil Xtreme Endurance Dual Valve Springs (OD 1.34" & rated up to .65 lift)
-REV Seat Locators
-REV Titanium Retainers
-Custom Xtreme Energy RPM (XER) Comp Cam (238/244deg duration / 114deg LSA)
-Comp Magnum Pushrods (7.8inch)


Thanks,
Alex

 

It's very unlikely that the cam broke. It's possible that the lifter broke and chewed up the cam. If the lifer broke then that would make the valve not open up properly.

 

Well after looking at a few diagrams of how engines work and reading what you said, i have a new question. Is the pushrod supposed to be secured to the lifter? I am able to just remove the push rod right now (rocker arm removed) without anything holding it into its hole.

 

Normal, if I understand what you are saying.


Mr. Sam

 

Ok so if the push rod is supposed to be loose like that, then the valve is doing a lot of the "pushing" to hold the pressure against the rocker arm onto the push rod?

Maybe the valve is broken.

 

sounds like a bad lifter to me... the pushrod should not be loose with the rocker arm installed, if the rocker arm is removed then yes it will be loose and can be removed freely... I agree with the above post, if the lifter collapsed or rotated in it's bore then it most likely took the cam with it and quite possibly the rocker arm too

 

So in your opinion, good chance the cam got thrashed too, right?
The rocker arm is 100% good. Removed it and it looks perfect. I actually bought an entire set of rocker arms to use for replacements, compared the one i just pulled and they are cosmetically identical, no broken parts whatsoever.

 

Also what is the proper procedure for getting to a lifter? Do i remove the whole head? I'm not a qualified technician by any means but like to try things myself. Anyone know where i can find a guide to something like this?

 

if the lifter collapsed or rotated then yes, most likely it took out the cam lobe(s) on the affected lifter(s)... check the rocker arm where it meets the valve stem, usually in these cases that area will be marred up and can damage the end of the valve stem as well... this is due to the pushrod being loose and recklessly banging up and down on the rocker arm... you will need to remove the head and that will give you access to the lifters and trays and go from there... if this is what happened the block is usually salvageable and can be rebuilt, whether or not it's worth it is up to you

 

Turn engine over a couple times and see if all the other pushrods do their job except the one in question.If so you have a collapsed lifter and need to replace all to do the job right.

 

Replace all the lifters?

 

Since the engine is on a stand and easy to work on,you might as well pull cam and check for damage,thus replacing whatever it needs while you are in there.All depends how many miles are on the valve train pieces.Might as well do it right while it is easy to get to.If you have a damaged lobe and/or lifter then there is likely metal debris in engine that will mean a tear down to clean up.

 

Guys, he said the pushrod was able to be easily moved with the rocker arm REMOVED.


Mr. Sam

 

Hey Sam, does that change what you mentioned earlier? Was the push rod not supposed to be able to be removed while the rocker arm is removed?

 

With the Rocker removed the push rod will be loose as a goose. Remove the head, lifter trays and lifters if you can and you will see exactly whats going on. If the lifter doesnt come out then remove the cam. Then take it out the bottom. That should tell you your issue.

What was the car doing that you replaced the motor?

 

made a loud squeeling sound, a clanking sound, and oil pressure dropped to zero. I think that the oil pump may have died, which could have caused the problem, but im not really sure.

 

Here are some LS6 disassembly picts for you to explore:

LIFTERS IN LIFTER RETAINER BUCKETS:



HEADS REMOVED EXPOSING LIFTER /BUCKETS

 

Thanks Bill!

 

Well got the head off today...really not as bad as i thought it would be. Took about 20-30min by myself, and i had no idea what i was doing.

The lifter on the problem area is definitely stuck. I tried some needlenose pliers with no luck. Read online there is a specific tool for the job that i can rent from autozone.

From what ive seen so far, the cam actually appears to be fine. My mechanic told me he's pretty sure the cam is fine or it would not have ran at all while it was still in the car (i guess he turned it on while i wasnt there). I have not seen any broken parts anywhere whatsoever, and i have the oil pan off the bottom of the block, nothing strange or unusual.

I'm honestly thinking this is as simple as replace the lifter and done deal. Hope im right. At the same time, it'd be extremely annoying if it was that simple and i just dropped $10k on a new motor + install.

I have all the front accessories off the motor, how do i manually turn it?

 

Since nobody else mentioned this and since you are asking fundamental engine questions. These are hydraulic lifters which means they need to be filled with oil to work properly. The question is, did this lifter fail and cause the engine oil pressure to drop or did the oil pressure drop causing the lifter to collapse? Not sure about the squealing sound you heard, but the clanking sound was probably the pushrod hitting the bottom of the lifter. Not sure why some here were so sure the cam was ruined. A collapsed lifter will ride up and down the cam lobe with no problem. Now if it rotated, being a roller lifter, that's a different story.

Before replacing any lifters, they need to be filled with oil or you will hear a lot of clanking. In fact, there are quite a few things you need to do properly before even thinking about starting this engine. Taking this engine apart without a service manual is 1 thing, putting it back together is another. Get a factory service manual.

Disclaimer: I have had enough experience ripping into the engines of my earlier corvettes (350, 427) and knew them inside out. However, other than pulling the plenum to replace my oil pressure sensor, I have yet to dig into my LS1. So, I am no expert on LSx engines. Wish you lived closer. I would of loved to come over and help you out.