Head torn down, should I replace my rockers?

[Earendil]

What's the theory and/or superstition on rockers? Do they "wear out" and break, and thus should be replaced simply because they are old, or is it perhaps one of those "if they lasted this long they must be good ones!" and not replace them?

I don't want to throw $250 at a problem that doesn't exist, especially if getting a "bad" rocker is a possibility that'll break on my first track day of the year.

Any idea how to tell if a rocker is too worn? Thanks guys!

[Ether-D]

You can look at the part that rides on the cam. It should have a smooth uninterrupted arc to it. Also you could look for cracks. But idk about track cars.

[Earendil]

You can look at the part that rides on the cam. It should have a smooth uninterrupted arc to it. Also you could look for cracks. But idk about track cars.

So no flat spots allowed on the patch that contacts the valve at all? Where do cracks usually form?

[digger]

What's the theory and/or superstition on rockers? Do they "wear out" and break, and thus should be replaced simply because they are old, or is it perhaps one of those "if they lasted this long they must be good ones!" and not replace them?

I don't want to throw $250 at a problem that doesn't exist, especially if getting a "bad" rocker is a possibility that'll break on my first track day of the year.

Any idea how to tell if a rocker is too worn? Thanks guys!

if you can see wear on the foot other than a mirror finish from use then they should be replaced and probably needs a new cam to suit. if the cam has a groove it needs replacing

post some high res pics its hard to put into words

[SkiFree]

^^This

On the cam check by running your finger nail across the lobes and the journals, it should be smooth. If you feel bumps plan on replacing it. If you've got pitting/wear on the backside on the cam lobe, this is a sign that the valve lash was set way too tight.

As for the rocker, also check for pitting (a good sign of a lack of oiling) along with the curvature of the pad. The curve should be continuous in its arc.

Here's a worn rocker I pulled.

[MR 325]

Rockers definitely do wear!

[Northern]

If you plan on re-using them and you're worried about cracks, you could always LPI them with a dye penetrant. It may cost you $60 for the cleaner, penetrant dye, and developer, but if it is cracked it will be worth it.

This.

Top 3 items here. you should be able to find the same/similar stuff locally.

Some will say this is overkill, but it depends on your level of paranoia.

[Earendil]

Okay, based on what you guys have said it's likely that I should replace my rockers. I think my cam shaft looks good though, but I'll post pictures of everything for you and future readers consumption.

Clicking on the images will take you to a much higher resolution version.



This image shows the absolute worst pitting on the entire shaft by a very long shot. All contact surfaces basically look like what you see on the left lobe.


A different lobe, and another example of what all the contact areas look like.



I'm now of the mind that all these rockers should hit the trash bin.

[SkiFree]

Yep, I wouldn't reuse the rockers. Wouldn't run the cam either. As I mentioned earlier the pitting is a result of poor oiling, specifically oil not sticking to the rocker pad and cam lobe. This is a good example of how not running ZDDP with your oil will wear your valvetrain.

While you,re in there consider flushing or replacing your sprayer bar. That one cam lobe being worn more than others is a sign that the aligning hole in the sprayer bar is clogged.

[Earendil]

Yep, I wouldn't reuse the rockers. Wouldn't run the cam either. As I mentioned earlier the pitting is a result of poor oiling, specifically oil not sticking to the rocker pad and cam lobe. This is a good example of how not running ZDDP with your oil will wear your valvetrain.

While you,re in there consider flushing or replacing your sprayer bar. That one cam lobe being worn more than others is a sign that the aligning hole in the sprayer bar is clogged.

What's the failure case for a cam shaft with pitting? Is it increased wear on the rocker? Anything else? And I realize you may not know the answer, but are we talking decreasing rocker life from 100k to 50k or something? Because at some point paying $200 for a new camshaft just doesn't seem worth it... I dunno. bah! I Tore the head apart to get it pressure tested because of an unexpected gasket failure, I had not intended to put a lot of money into it right now.

Maybe trading a 2014 track day for a cam shaft is worth it...

That's a good note on the sprayer bar. I was going to clean it up anyway but I hadn't yet made the mental jump to assuming a single exit point might be clogged causing the pictured damage.

[SkiFree]

What's the failure case for a cam shaft with pitting? Is it increased wear on the rocker? Anything else? And I realize you may not know the answer, but are we talking decreasing rocker life from 100k to 50k or something?

There is no right answer. Its relative to the driver and the engine.

Example 1) I've had a guy who ran the Manaco Historic Rally in an E21 323i who absolutely destroy a set of brand new rockers over that weekend due to NO break in on new rockers/ used cam and NO ZDDP.

Example 2) I've also had a team running LeMons limp a worn cam/rocker setup for a season (doing due diligence on oil changes and valve lash adjustments).

As digger mentioned I would not change out the rockers while keeping the cam (then changing the cam down the line) they tend to wear together.

[digger]

bite the bullet since you are rebuilding, you be surprised how a completely freshened topend puts a smile on your face compared to a tired one

if i saw that on an engine i was adjusting valves on and nothing being taken out or disturbed id be inclined to let it go though and use a better oil

[digger]

most likely on a stock cam pitting would be caused by excessive sliding friction (poor lubrication) which could be wrong oil without sufficient zinc/phos (or contaminated oil) or not enough flow going to the head due to blockage?

[Earendil]

I don't have much history on the head, except that the chassis has over 300k and the inner and outter valve springs were replaced 4 years and maybe 30k miles ago. After which time she's had good oil, and good oil changes. But they could still be ancient.

Well, I have the parts ready to go. As soon as I hear back from te machine shop that my head is still good I'll bite the bullet. Hopefully I'll have an engine that will run the body into the ground :)

[TobyB]

Yep, and use either a designated break- in oil or an additive.
And then a high- ZDDP oil for at least a few changes after.

It takes a while for a cam and rockers to mate completely, and
before they do, the oil is pretty darned important.

t