rocker noise question flipping it around?

[redstack]

I have an 84 3.2 ROW. The PO mentioned that some of the rocker noise was due to a problem with one of the rockers and that it could be fixed by flipping it around or over. What in the heck was he talking about?

I did a valve adjustment, that was a learning experience, but I can't say that the clicky clack has changed much since. It does seem to start out quiet but once warm I hear the normal valve train noise.

Anyone have any thoughts what he means by flipping the rocker around? Maybe move a exhaust to the intake side? I can't even tell which one he might have been told was the problem.

[mreid]

A noisy rocker that can't be adjusted should be replaced, period.

[Tippy]

Originally Posted by redstack

I have an 84 3.2 ROW. The PO mentioned that some of the rocker noise was due to a problem with one of the rockers and that it could be fixed by flipping it around or over. What in the heck was he talking about?

I did a valve adjustment, that was a learning experience, but I can't say that the clicky clack has changed much since. It does seem to start out quiet but once warm I hear the normal valve train noise.

Anyone have any thoughts what he means by flipping the rocker around? Maybe move a exhaust to the intake side? I can't even tell which one he might have been told was the problem.

I'm going to get flamed for this, but this is what I do. My rocker bushings are really worn. In the past, I'd adjust them repeatedly to 0.004", but could not get them quiet. I knew I was doing this correctly, so it dawned on me the slop did not reside in the rocker pad to cam lobe interface, rather the rocker bushing to rocker shaft interface.

So, I adjust them to 0.002". Quiet as can be afterwards.

Caveat - you have to make sure you don't over tighten causing valve to piston contact!

[Steve@Rennsport]

If I were you,....I'd remove the rockers and have them properly reconditioned.

Running .002 valve clearance will result in needing new exhaust valves before long and THAT is far more expensive than rebuilding your rockers.

[Tippy]

Why is that, Steve? Curious.

I noticed my valve faces were fairly white since I had my intake off.

3.2 (3.4) BTW.

[snbush67]

My guess is that Steve is going to say that the valve seat and edge of the valves will not dissapate heat properly and cracks may develop on the valve edges.

I could be wrong, just a SWAG.

[Steve@Rennsport]

Originally Posted by Tippy

Why is that, Steve? Curious.

I noticed my valve faces were fairly white since I had my intake off.

3.2 (3.4) BTW.

Because you will wind up with burned valves due to insufficient heat dissipation.

[Tippy]

So this occurs during warmup?

Doesn't the rocker gap widen once fully warmed?

[snbush67]

My guess is that Steve will write that no, the damage likely doesn't happen during warm up, but rather as the engine reaches higher temperatures. I think that he will also confirm that the gap widens as temperature increases.

[mreid]

I always thought the gap closed as components heated up. Learn something new all the time.

[fanaudical]

Gaps change as temperature increases, but there still needs to be a gap when hot. That is the only way that the valve completely seats in the head, which then allows the heat in the valve to conduct away into the cylinder head (thereby cooling the valve).

[redstack]

So that would explain why the noise increases as my engine warms up.

[dap930]

redstack,

My engine has done the same thing since I overhauled it several years ago. During the overhaul, I had the rockers rebuilt and installed new rocker shafts. Every valve adjustment produced the same results; a tick - tick - tick after the engine warmed up for a couple of minutes. I could not get rid of the tick - tick - tick. Then last year I had to pull the engine for a clutch job. I decided to remove the rockers and shafts from cylinders 1 & 2 where the noise was coming from to inspect for wear. Well the rockers and shafts looked and fit good with no noticeable wear. And the cam lobes looked good too, no uneven wear patterns. The only thing I could find was that a couple of the adjuster swivel cups were noticeably more loose than the others. So I replaced those with new ones. Also, I adjusted the valves using the backside method.

After reinstalling the engine, the tick-tick-tick is now gone. So I am not sure what corrected the problem, the replaced adjusters or the backside valve adjustment, or a combination of both, but at least the tick is gone.

[Tippy]

Originally Posted by fanaudical

Gaps change as temperature increases, but there still needs to be a gap when hot. That is the only way that the valve completely seats in the head, which then allows the heat in the valve to conduct away into the cylinder head (thereby cooling the valve).

Right, so if I do 0.002" at cold, it should be greater as it heats up and not be an issue.

Someone here posted years ago that the gap increased to like 0.008" when tell engine fully hot discovered by a reputable mechanic/Porsche crew member.

I would think there would only be a problem if you had the rocker lash adjusted to the point the valves were lifted from the seats at 0.001" or more?

To Steve's point, the face of my valves (opposite side of stem) looks white. This might explain it, but I'm trying to figure how if I in fact have a gap.

Sorry for thinking out loud here....

[Ronnie's.930]

Tip, Steve W. has a lot more knowledge and experience than I do with these engines, but one interesting thing about the .002" gap is that it falls within the factory valve lash specifications (.004, plus or minus .002 - aka the cold engine lash range is .002-.006).

Of course, there is a long list of poor judgements made by the designers of these cars (dilivar studs, ****ty wiring practices, a steering wheel used in the 1980s that looks like it belongs in a station wagon or bread delivery truck, etc., etc.) so the factory did not always know best.

[Tippy]

Originally Posted by Ronnie's.930

Tip, Steve W. has a lot more knowledge and experience than I do with these engines, but one interesting thing about the .002" gap is that it falls within the factory valve lash specifications (.004, plus or minus .002 - aka the cold engine lash range is .002-.006).

Of course, there is a long list of poor judgements made by the designers of these cars (dilivar studs, ****ty wiring practices, a steering wheel used in the 1980s that looks like it belongs in a station wagon or bread delivery truck, etc., etc.) so the factory did not always know best.

Ronnie, you know what? You're right, I forgot about that spec and was the reason I tried it.

Thanks for jogging memory.

[KTL]

Nope you can't flip a rocker arm around to combat noise or wear. It can only be installed in one direction. And swapping rockers around on the engine is foolish because you're mixing up wear patterns between the cam lobe and the rocker pad.

Speaking of wear patterns, i'm of the opinion that a lot of folks complain about improperly refinished rockers by their own fault. They do a good thing by having their rockers reconditioned, but they decide to leave the cams as-is in their worn/looks-good-to-the-naked-eye condition. I'm not saying the cams are necessarily bad. Just saying that you shouldn't refinish one surface and not the other. When they see uneven wear on their "new" rockers? They assume the shop who reconditioned them didn't do it right.

I think a lot of the valvetrain noise people experience after adjusting the valves is due to adjustment error. The error they make is being too deliberate in following the often recommended description of "light drag" on of the feeler gauge. You usually have to bend the feeler gauge to get it in the cam housing and wiggle it in between the valve and the foot. That slightly bent feeler gauge is automatically going to add some light drag to the feeling of the clearance and therefore make the gap much larger than desired. I think the sensation of drag needs to be recognized as being much more firm in order to get a good clearance measurement with the bent feeler gauge.

[cgarr]

You can also develop a ridge or wear pattern in both the adjuster foot and valve stem which makes setting them with a feeler gauge almost impossible because the gauge will ride on the ridges but when pulled out the valve and foot set back into the wear area, and it only takes a few thousands. That is why I like to use the 8x1.0 adjuster screw like a micrometer to set gap.

[Tippy]

Originally Posted by cgarr

You can also develop a ridge or wear pattern in both the adjuster foot and valve stem which makes setting them with a feeler gauge almost impossible because the gauge will ride on the ridges but when pulled out the valve and foot set back into the wear area, and it only takes a few thousands. That is why I like to use the 8x1.0 adjuster screw like a micrometer to set gap.

Interesting observation Craig! Never thought of that. Right on.

[hcoles]

+1 Craig re. "like a micrometer" - does this imply the back side method could be used instead?