During my PAC 1518 spring install today, I discovered a cracked OEM spring retainer on the Cyl #4 Exhaust valve. Did a quick visual check on the other retainers on the RH head and all look OK. Haven't looked at the LH head yet.

Looks like there might have been a large ding or flaw on the edge of this retainer that caused a stress riser. In the 2nd photo, you can see the crack running from the edge towards the center of the retainer.

Anyone else see anything like this with the OEM spring retainers when you did a spring swap?





So ... question is: Does anyone make a better quality, exact direct replacement retainer that will use the OEM split keepers and give me the same exact spring installed height? If so, then I'd probably replace them all with something aftermarket. Open to any suggestions.

If not, then I think I'll just get a new OEM retainer from the Chevy dealership. I'm hoping this was a freak occurrence due to a dinged or defective retainer during manufacturing. I'm the original owner of this Z06 (currently has 21K miles), and the motor has never been open until now.

 

Good CATCH! Just get another OEM retainer and keep everything the same.

 

I didn't need to see this! I put 1518's on stock retainers in my '02 Z last spring (broke an OE spring) and (crosses fingers and toes, knocks on wood) no issues yet. BUT, I just installed a .644" cam...

I realise your spring choice has nothing to do with this failure, but it's a bad coincidence for me, that's all. I don't think I looked that closely at my retainers, but I probably would have noticed an edge defect like that if there was one there.

Count yourself lucky! If a retainer fails it's new engine time! When my spring brke the keepers stayed in the retainer and held the valve up off the piston. I got real lucky.

 

That's what I'm thinking of doing. I'm not sure if there are any aftermarket direct OEM replacement retainers for the LS6 or not. I don't want to hassle with putting in new keepers with different retainers if that's the only route. If I could find a high quality aftermarket set that would drop in I'd think of that as an option.

I think this is probably a rare case ... looks like there was a flaw or ding in the edge that caused it to stress and crack over time.

 

Wow ... that's a big lift cam! Sounds like the 1518s will get a work out with that cam. I'm just installing 1518s for reliability over the stock OEM yellow springs ... mine is a 2002 also, and don't want a spring failure.

I actually found it when I was cleaning the retainer and felt that big gouge/crack in the edge. Then I looked at it really close under good light and saw the crack ... now I'm all over the other retainers looking for damage.

 

That's exactly why I used them as well, I wanted a spring that would last forever on the stock cam. Then about six weeks ago my cam and lifters went! Several here suggested the heat treated depth of the cam lobes flaked off, and sure enough that's what I found when I went in to fix it.

Hence the cam upgrade!

I think I'll have a look at my retainers very soon... with 120k miles on them I'm pretty sure they're OK, but you never know.

Great pics BTW! Do you have a macro lens on an SLR?

 

Decided to look at everything now ... even the split keepers. Well, look what else I found. One of the keepers on the same valve that had the cracked spring retainer is damaged! I'm thinking this could now be related to the damaged retainer. Looks like the keeper was forced in during assembly. Still going to inspect every last retainer and keeper now. Lucky, this was only the 2nd cylinder I did ... so will only have to go back and remove the retainers & keepers on Cyl #2.

See major material smear and crack on bottom lip of keeper. I inspected the tip of the valve where the keeper groove is, and there doesn't appear to be any damage.



The keeper on the right is the top of the damaged keeper. Looks like some kind of tool had impacted the top lip. Wonder if a machine puts these in at the factory? Had to be factory damage, as this engine has never been opened up since the day I bought this car new. No flash on this shot ... used reflecting flashlight to show the dimples in the keeper edge.

 

That sucks! ... maybe since you had so many miles it gave up on you. You don't think the stiffer valve springs had anything to do with that? - I would doubt it.

Yeah, surely wouldn't hurt to even just buy a new set of OEM retainers just to be safe. They can't be very expensive ... guess I'll find out tomorrow what a retainer and keepers cost (hope I can buy just one).

My digital camera is just an old 5 Megpixal Fuji E550 (5 yrs+ old now). I does have a close up mode and a decent flash, so get some pretty good photos out of it.

 

Have you ever had those removed at a machine shop while you weren't looking. They just pop them on top with a large socket and the keepers come loose. It would explain both damages. Just asking...

 

I bought this Z06 brand new, and the engine has never been opened up until now, by me. I think something must have went wrong during the assembly of this particular valve at the factory. I'm lucky something didn't let go, and lucky I opened it up now instead of much later.

 

Perhaps PAC has a recommendation.

 

I'm telling myself that it's all coincidence... but if it IS, it's one heck of a coincidence. I replaced the springs last spring, now ~10k later the cam/lifters are shot. Coincidence? Maybe. Not likely, but maybe.

I have a feeling that the cam did indeed fail, taking out the lifters... a couple of lobes showed some surface "flaking" and the coresponding lifter roller still looked pretty good.

The PAC 1518 will increase open force by only 3% or so compared to the LS6 springs on the LS6 cam (this is a major reason I went with these springs), BUT the seat load goes up considerably which may or may not have caused a significant increase in the lifter roller and cam lobe temps. Which may or may not have caused/accelerated this issue.

Peak wear on the cam lobes was at the tip of the lobe at max lift, theoretically where the change in spring force would be the least.

The Engineering side of me says there's a much greater likelihood of lobe-to-lobe variations in heat treating on the cam than there would be on roller to roller heat treat in the lifters. That's only a likelihood, though.

My "opinion" is that my cam and lifters would have likely failed at some point regardless of whether I upgraded the springs or not. This is based on my belief that the cam was not heat treated properly, and this belief is based on a lot of fedback from other members who've said heat treating is a common problem on camshafts.

Who knows... had I upgraded my springs at a much earlier mileage as you are doing now, my cam and lifters may have lasted exactly the same amount of time. This is a long winded way of saying I don't know.

 

Looking at your (excellent!) pictures of your damaged keeper, I'm going to throw out a theory:

I think your keeper was damaged during manufacturing, was not caught during QC inspections, did not seat properly in the retainer and caused excessive strain on the retainer as a result.

The flaw in the edge of the retainer may/may not have been there from the start. If it was, it provided a "strees riser" from which the crack formed. If it was not, the flaw could be missing material that broke away as the broken edges of the retainer moved relative to each other.

The keeper definitely looks like it was damaged during manufacture, not during assembly. If it were assembly damage the valve and/or retainer would show damage as well as they would have had to apply the damaging forces to the keeper.

I'm going to go with the keeper damage being the culprit and the retainer damage (including the edge material missing) the victim. Whatever the case, you are one seriously lucky Corvette owner!

 

That's why I went with the PAC 1518s too ... because the open load was essentially the same as the OEM spring at max valve lift. Yes, the closed valve's seat load is supposed to be about 130 lbs vs. 90 with the OEM spring, but I don't think that should have any effect on the cam or lifters since the valve is closed and there's no load on the cam lobe during that time.

Based on the other things you said, I agree your cam failure was probably just caused by a cam with a few lobes that weren't heat treated very well. Since the force on the peak of the lobes is essentially the same with the OEM springs and the PAC 1518 springs, that tells me it wasn't due to the new springs.

 

I think you're right that the keeper was damaged during manufacturing ... I say that because I don't see any corresponding damage on the valve stem or on the inside surface of the retainer where the keepers mate up. The damage on the keeper doesn't seem to protrude outside the normal plane of the keeper walls (inside or outside wall), and doesn't seem to interfere with anything the keeper mates with in that area. However, it's possible the keeper's shape might be slightly out or round near the bottom due to the impact there, and maybe that caused excess load on the retainer somehow to stress it out. All I know is that it's something that happened during the factory building the engine.

In any case, yes ... I'm lucky to have found this and will inspect every last retainer and keeper now. I found a local Chevy dealer who has these parts in stock, so will just replace the damaged parts with OEM ... should be fine.

 

I'm sure you will be. All of my OE retainers and keepers are perfect after a year with the 1518s, 120k miles total on the retainers (original) and ~10k on the keepers (replaced them with new OE parts same time as my springs), and now with a high lift cam they seem to be doing well also.

Let's hope you have better luck with the cam than I did! If you ever hear a ticking/rattle coming from the engine check out your lifters right away! And if the cam/lifters ever grind each other up, make sure you replace your oil pump - mine was all chewed up inside from pumping cam lobe shavings.