When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
So we were in the process of replacing the valve springs on my ‘03 Z. Once we got the rockers off this is what I found.
Pretty severe looking wear to the tips of the valves where the rockers ride. All of the valves are showing similar wear. Some worse than others. My friend whose a master level professional technician, is STRONGLY recommending that I replace the valves. I was definitely not expecting anything like this because the car only has 31,xxx miles. I really don’t want to pull the heads but certainly will if necessary. Opinions from the group as always are much appreciated!!
Hard to tell how bad they are from the photo because photos tend to make things look worse than they are. Not sure if you could use lash caps or if they would even fit. You may need to shim the rockers and increase pushrod length with lash caps. As I recall, valves are 8mm diameter but don't trust my feeble memory >>>> 8mm Lash Caps
Other issue is that I'm not sure the LS6 valve are still available from GM, which means heavier valves and stronger springs to control them at the higher LS6 RPM capability.
what I would look for is what caused it so it didn't happen again ?
My guess as to what caused it is too many start ups after the car had been sitting for extended periods of time. Considering it’s an ‘03 with only 31,xxx miles it has spent a lot of its 15 years sitting around. After sitting awhile the valve train dries out. Then maybe on start up the car is not even driven or allowed to warm up properly. Wear over time. PITA now!
That's one of the biggest reasons to go to a full roller rocker..
I know that the stock ones work fine... But there are advantages to
a full roller (with roller tip too)..
Why can’t a machine shop resurface the end of the stem?
Don't think the hardened surface thickness is enough to allow this.
A photo will really magnify things so not sure how bad they are. I took pictures of an issue I had with a cam several years ago. The lobes definitely had some morkes on them but when I took the photos they looked like they were totally destroyed and the surface of the moon.
Thats what happens when the roller rockers flex from bent pushrods/improper clearance/loose roller rockers/defective valve guides. Check your pushrods and make sure they are all straight, also check the geometry of each. You do that by taking off the rockers and applying a dye to the tip and then turn over the motor by hand and that will show you the wear pattern. if it is not centered you may need new rockers and/or pushrods
Have you checked the roller tip for excessive wear? Replacing the valves does not fix the underlying problem. Valve stems usually have wear its an abused part of the valvetrain.
Thats what happens when the roller rockers flex from bent pushrods/improper clearance/loose roller rockers/defective valve guides. Check your pushrods and make sure they are all straight, also check the geometry of each. You do that by taking off the rockers and applying a dye to the tip and then turn over the motor by hand and that will show you the wear pattern. if it is not centered you may need new rockers and/or pushrods
Have you checked the roller tip for excessive wear? Replacing the valves does not fix the underlying problem. Valve stems usually have wear its an abused part of the valvetrain.
Your friend is giving you good advice. That's 16 wear surfaces creating metal shavings, not to mention if it's causing excessive wear on the 16 rockers. It's the highest PSI pressure in the motor, and the surfaces are too rough for the oil film to protect, sorry to say.
Your friend is giving you good advice. That's 16 wear surfaces creating metal shavings, not to mention if it's causing excessive wear on the 16 rockers. It's the highest PSI pressure in the motor, and the surfaces are too rough for the oil film to protect, sorry to say.
Thanks Apex. That’s an explanation my pea brain can understand. Looks like I’ll be pulling the heads this weekend. I’m a little intimidated but will have some help and will soldier through. I really wasn’t planning to do many mods to the motor but now that I’m gonna be in there anyway.....
With that level of wear -- too much to ignore, but not beyond hope -- why not try the lash caps first? Not terribly cheap, since it would seem likely you will need new push rods too, but significantly less work and time.
03-12-2018, 12:02 AM
Do I Need to Replace My Valves?!?!
