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gerard vaglio's Avatar
 
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Valve adjustment creep?

I want to coin a new phrase, Òvalve adjustment creep,Ó but first, I need to confirm itÕs actual existence.

Last week my engine developed a tapping sound on the passenger side.

No problem. I adjust the top, right side intake valves first hoping to catch the tapper without having to do the exhaust ones on the bottom, theyÕre more work. I button it back up but ...no joy, the tapper must be on the bottom.

No problem. This morning I jack up the right side of the car to let the oil run into the other side of the engine. This is a good trick if youÕve never tried it, it keeps you from having to drain the oil, a real time saver. A remarkably small amount of oil drips out with this shortcut by the way. Also, I donÕt take out the spark plugs either, itÕs easy enough to turn the engine clockwise with a common household garden variety ratchet attached to the fan nut.

So anyway, I carefully adjust those bottom three exhaust valves, button it up and ...TAPPING? Less tapping then before but tapping none the less. So the tapper is on the bottom after all.

But I have a larger question here.

Generally, I snug things up against the feeler gauge a little on the tight side to avoid tapping and adjusting on the tight side also gives a little more performance. I tend to go as tight as I can while still being able to wiggle the gauge out after the lock nut is tightened down. It takes some extra wiggling but itÕs worth it, who wants tapping. Of course I hold the adjustment in place with a screwdriver while locking down to avoid the lock nut tightening the adjustment further. Hey, who wants burnt valves.

I even double check my work by grabbing the rocker arm and pushing and pulling to see if there is any extra play. Push, pull, push, pull, push, pull trying to simulate a running engine while I listen and feel for any tapping. If my spider senses detect anything more then a barely noticeable bit of movement too small to tap, I readjust. If I get no movement at all, it feels solid for instance, thatÕs too tight and I readjust. If I feel a gap large enough to create sound, tapping, I also readjust. Before moving on to the next valve there has to be just the slightest amount of play up and down, the amount of space that should be left once the feeler gauge is removed. Since IÕm only adjusting three at a time I can afford to be lavish with my time.

But this raises the question of adjustment creep?

IÕm struck by the fact that even if my method is consistent and conservative the resulting adjustment seems to vary? Based on what IÕve just described the same meticulous procedure will result in adjustments raging from just a little too tight to just a little too loose. Before starting the engine I would have bet my entire collection of Miles Davis CDs that this engine WILL NOT TAP.

Yet it does?

My engine is a stock 3.0 with 150k on it. As engines get older are they just too worn to adjust perfectly? Has anybody else noticed Òvalve adjustment creepÓ while adjusting their valves or am I going to be exposed here as a valve adjustment poser?
Old 07-05-2005, 07:16 PM
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you can really adjust the valves on one side without draining the engine oil if you lift just that side?? how high to do you have to go? when you did this did you reuse the same gasket or do you have to always use a new one? i'm tempted to try this on the right side as well, as i have more tap there (it's been over 2 years since last adjusted)..i wonder if i break the gasket seal to quickly try this if i could get the old gasket to reseal? even if it leaked a hair it wouldn't matter much..it's already oily and i could replace all this winter when i change to winter oil.
ryan
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Old 07-05-2005, 07:22 PM
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Ha. I just did the same thing to my SC.
Unfortunately,I didn;t jack the car high enough to the right and made quite a mess. I narrowed my tapping to the driver's side exhaust. Adjusted them "tight" no more tapping. Well,maybe a little, but not as bad. My 3.0 has 150,000 as well. I have the silicone gaskets so I can reuse them. Just ran the car around 600 miles this weekend, nice and quiet.
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Old 07-05-2005, 07:51 PM
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All I do is raise one side untill the rear tire almost moves away from the ground, ten, twelve inches maybe. Leave it for twenty minutes while your collecting your tools. Almost all the oil will migrate to the other side and out of your way. I never drain the oil.

Put some newspaper over your exhaust pipes and under them as well to catch the few ounces of oil that drizzle out. You'll be shocked how little comes out.

Always use new gaskets nuts and washers.

That said, I don't. If the gasket isn't too old just carefully wipe the gasket with a paper towel before you close. If you do develope a leak it will be small and you can always order a fresh gasket later if this does happens. Don't try to remove the gasket if you think your going to reuse it, you might damage it in the process.

If your bored, take your valve cover into the living room and find a nice glass coffee table. Put a super fine grit black emory paper on the glass and place the valve cover on it and rotate in a circular motion. This will polish off the high ridges and make the valve cover seal better then it did before. Rinse off any grit, don't want that inside the engine.

If your only going to do one side of the engine at a time, which is much, much easier, be certain of what valve your adjusting because your adjusting slightly out of sequence. You'll be skipping so you'll have to rotate 120 degrees + 120 degrees to get to your next valve. Sounds harder then it is.

To make it even less likely that I'll make a mistake I used nail polish, paint Z1 red, rotate 120 degrees paint white, rotate 120 degrees paint white.

Using these short cuts makes valve adjustment more like part of a simple tune up instead of the bear it was the first time I did it.

Watch out for the valve creep.
Old 07-05-2005, 08:14 PM
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thanks, gerard..i see how giving it a little time to flow over probably helps reduce the dripping. good tips. i will try this soon.
ryan
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Old 07-05-2005, 08:21 PM
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Well at least it is good to see I'm not the only person getting some tapping. I'm not too sure I adjusted mine right. I made sure the feeler guage could be held in and the rocker could not be moved with the guage in. I think I'm going to pay to have mine adjusted to see if it will quieten down.
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Old 07-05-2005, 08:42 PM
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It is my opinion based on experiance that the exhaust ones do get tappier than the intake. I have assumed that is is due to the higher heat handled by the exhaust side of the head. But I also asumed that the extra heat meant extra expansion and therfore less room to go tight on the adjsut than the intake. Several years back after adjusting and readjsuting my buddy at andial told me the tapping I was chasing was the rockers side to side not the valve lash. So now I just deal with it. But I Also found that I was not adjusting properly. I found that if I ran them down too tight then backed it off to get proper adjustment I got a better longer lasting adjustment. Seems like when they lossen up they get more oil built up in the swivil foot. I needed to squeeze out the excess. Worked for me.
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Old 07-05-2005, 09:02 PM
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If your valveguides are worn, adjustment will be very tough. They may be getting there at 150k miles, even though the SCs generally hold up longer than the 3.2 Carreras. An even tapping on all cylinders is normal on the flat six and music in my ears!

George
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Old 07-05-2005, 09:09 PM
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Is loud tapping a sign that the valves need adjusting?

Mine are overdue for an adjustment, but they sound smooth as silk and the car runs great...
Old 07-05-2005, 09:32 PM
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Quote:
Is loud tapping a sign that the valves need adjusting?
absolutely..
ryan
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Old 07-05-2005, 09:34 PM
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and quiet ones mean not ready for adjusting?

(probably not)
Old 07-05-2005, 09:36 PM
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i think they're recommended to be adjusted every 12-15,000 miles, but i tend to go by the sound..when i hear that tapping..
ryan
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Old 07-05-2005, 09:40 PM
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Its too tight valves that you should worry about. They will be nice & quiet until they burn & break apart due to excess heat buildup
Old 07-05-2005, 09:41 PM
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Yup, ubiquity0 is right. And with time the lash gets smaller! The valve seats wear the most in the valve train, so the valves practically sink into the heads over time. A lot of people think things get loose over time, but it ain't. Things tighten up and if you wait it out, you'll have burnt exhaust valves ...

George
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Old 07-05-2005, 09:48 PM
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Thanks aigel, my valve guides may be worn at 150k.

Yup, ubiquity is right, tapping just means their loose but the quiet ones are potentailly too tight, big problem.

Adjusting every 10,000-12,000 miles was a good suggestion.

A few years ago I gave the car to a "Porsche mechanic" to do the valve adjustment. When he finished he said one valve still taps.
Old 07-05-2005, 10:52 PM
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Light tapping is not unusual or anything to worry about, imho.

Adjusting them "tight" is not correct (again imho) but that's your choice.

12k between adjustments is correct i believe.
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Old 07-05-2005, 11:11 PM
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GUys I adjustred my valves and it sounds like a "sewing machine" not to crazy but you can hear it a little. Cheers james


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Old 07-06-2005, 04:18 AM
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There is mechanical noise to the rockers. If it is even across all of them and not very loud, it is normal. Best is if you go see other 911 owners and listen to their engine. You'll get a feel for it.

George
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Old 07-06-2005, 08:45 AM
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I'll try not to let my tappy valve bother me too much right now, I'll open my lower right valve cover, AGAIN, this weekend and look for the unhappy valve. Hey, there are only three in there so how hard can it be.

And now for some back peddling. I didn't mean to suggest that valves should actually be adjusted tight in my earlier post, they shouldn't.

With my motor I've come to think of tight as more drag on the feeler guage as opposed to less. I've learned to do this over time to help compensate for my valves tendencies to tap only AFTER I close everything up.
Old 07-06-2005, 08:08 PM
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