bad rocker?

slyguy · 08-10-2009, 01:55 PM

Just putting the motor back together, assembling the rockers shafts and doing the valves when I came across this... Can anyone tell me whats responsible for a wear pattern like this? Unfortunately I don't know which cylinder it came off of. Are other rockers at risk? Can it be salvaged or reconditioned or replaced altogether? Anything I need to look at? Outwardly the cam lobes are all in good condition, should I be looking deeper? This was a total suprise, motor was running great when I pulled it apart for the head swap.... Thanks

4sd911 · 08-10-2009, 02:15 PM

Definitely replace it. All cams lobes are good? No marks. Were cam lobes checked by a cam shop? Did you remove the oil tube in the cam housing? You should make sure the holes aren't clogged.

rvanderpyl · rvanderpyl's Garage

If you aren't reconditioning the rockers and cams they are supposed to go back in, in the same position they came out as the cams and rockers wear to each other in the break-end phase of a new build. Mixing them up wil produce accelerated wear in the future. As for that particular rocker looks like it had an issue with hardening.

slyguy · 08-10-2009, 02:37 PM

further inspection shows the lubricating holes in the rocker and bushing are misaligned... spray bar clog perhaps?

Flat6pac · 08-10-2009, 02:55 PM

When you have a rocker that looks like that you will have a cam lobe to match...I guarantee it
Your spray bar has a plugged hole for oiling that lobe
Bruce

cgarr · cgarr's Garage

Was the rocker bushing frozen up? you said there were no oiling holes in it or at least not lined up? Otherwise if the rocker was resurfaced past the hard surface and not retreated it could have caused this too.

slyguy · 08-10-2009, 06:14 PM

Bruce,
I'll be pulling the cams and spray bars tomorrow, new rockers on the way, hopefully the cam is not carved up although I'm not holding my breath. Thanks!

Craig, The bushing is actually slipped and the holes no longer line up. Whether it slipped first and starved or was starved and slipped as a result I don't know yet. I suspect the spray bars will shed a little light when I yank them. Thanks!

Tom

Steve@Rennsport · 08-10-2009, 11:29 PM

What oil have you been using?

slyguy · 08-11-2009, 05:03 AM

Quote:

Originally Posted by Steve@Rennsport

What oil have you been using?

I'm guessing you've seen this before... Was running castrol gtx 20-50 on 2500/3000 change cycle. I don't throw that many miles on the car comparatively and allow the turbo to cool with easy driving and idle when I do. Could coking of the non-synthetic be responsible for something this?

Flat6pac · 08-11-2009, 06:47 AM

You had a piece of lint through the oil system and it just happened to stop at that hole
Bruce

slyguy · 08-11-2009, 07:46 AM

smoked the cam and another rocker. Looks like spray bar on number 6 is culprit... Can this be re-ground? It's dug into the lobe about .4 mm. Do the lobes in the last photo look suspect as well?

milspam · 08-11-2009, 09:08 AM

slyguy:
Yep, thats tosted pretty good. Cams could probably be salvaged by Web cams or some of the other cam grinders. Check 9xauto for rocker arms which are currently 39.00 each, which is cheaper than getting them reworked. Just a suggestion, I'm not an expert by any means. Good thing you caught this before startup, I can just imagine the racket this engine would have made.

JFairman · 08-11-2009, 09:15 AM

Quote:

Originally Posted by slyguy

I'm guessing you've seen this before... Was running castrol gtx 20-50 on 2500/3000 change cycle. I don't throw that many miles on the car comparatively and allow the turbo to cool with easy driving and idle when I do. Could coking of the non-synthetic be responsible for something this?

Yes, I've been there and experienced the exact same thing and it was carbon particals in the oil from the turbo that clogged the cam spray bars.
The cooked and aerated oil from the turbo goes back to the oil tank unfiltered in a 930.

What really sucks is the stuff is everywhere throughout your engine, oil lines, and coolers now and you can only hope none of the piston squirters are also clogged.

camgrinder · 08-11-2009, 11:17 AM

From the looks of the cam lobe, I would say it cannot be repaired unless you weld it up. Typically its the spray bar that causes this.

I have a core r/b SC I could grind to 964 specs for you, assuming from your sig this was a 964 cam.
John

Steve@Rennsport · 08-11-2009, 01:01 PM

Quote:

Originally Posted by slyguy

I'm guessing you've seen this before... Was running castrol gtx 20-50 on 2500/3000 change cycle. I don't throw that many miles on the car comparatively and allow the turbo to cool with easy driving and idle when I do. Could coking of the non-synthetic be responsible for something this?

Yessir, I've seen more than my share of that problem.

I'm no fan of Castrol oils based on wear and dirt issues such as what you are experiencing. Further, coking is a problem with that oil in a 930.

Just as Mr. Laifman said, you likely have such material in the rest of the engine based on what I've seen with engines running Castrol GTX as it makes quite a mess. At the very least, I'd be inclined to clean the spraybars on both sides of the engine.

We send such cams to Webcam to be repaired and I always use new rocker arms. Its also very critical to break in the new or repaired cams properly otherwise the problem will recurr.

slyguy · 08-11-2009, 01:04 PM

Quote:

Originally Posted by camgrinder

From the looks of the cam lobe, I would say it cannot be repaired unless you weld it up. Typically its the spray bar that causes this.

I have a core r/b SC I could grind to 964 specs for you, assuming from your sig this was a 964 cam.
John

John,
Work up a price and time frame for me if you could, I'm at slivan@verizon.net Thanks!
Tom

slyguy · 01:13 PM

Quote:

Originally Posted by Steve@Rennsport

Yessir, I've seen more than my share of that problem.

I'm no fan of Castrol oils based on wear and dirt issues such as what you are experiencing. Further, coking is a problem with that oil in a 930.

Just as Mr. Laifman said, you likely have such material in the rest of the engine based on what I've seen with engines running Castrol GTX as it makes quite a mess. At the very least, I'd be inclined to clean the spraybars on both sides of the engine.

We send such cams to Webcam to be repaired and I always use new rocker arms. Its also very critical to break in the new or repaired cams properly otherwise the problem will recurr.

Thanks Steve for the insight. I'll be focusing on some spray bar cleansing for the next little bit, perhaps adding an inline filter for the oil return and making the swithch to full synthetic. I have a set of rockers on the way and am looking into having the cam repaired. Fortunately the heads are new to the engine and I've cleansed everything to the top of the pistons already. I'm hoping not to have to split the case, what in addition to the spray bars should be pulled apart?

Steve@Rennsport · 08-11-2009, 01:22 PM

Quote:

Originally Posted by slyguy

......what in addition to the spray bars should be pulled apart?

This is kind of an all-or-nothing proposition. Beyond pulling the spray bar galley plugs and cleaning those out, the only other thing would be to split the case, disassemble everything, remove the oil galley plugs and scrub out all the passages, followed by a half hour in the parts washer.

We always remove the oil galley plugs in the crankshaft and scrub out all those passages, as well followed by ultrasonic cleaning. Do the oil coolers, too.

camgrinder · 08-11-2009, 01:32 PM

Quote:

Originally Posted by slyguy

John,
Work up a price and time frame for me if you could, I'm at slivan@verizon.net Thanks!
Tom

Done!

slyguy · 08-11-2009, 04:48 PM

from the right side spray bar, lodged in the spray openings. left side was no better...