Worrying engine noise!
 

Gents,

Today when I started my car I heard a new noise from the engine: sound clip
The noise is coming from the passenger side. In the clip I move the mic from the passenger side to the drivers side at 9s, then back to the passenger side at 12s. My first (uneducated) guess is a collapsed chain tensioner? It's got the updated hydraulic tensioners.

After a short run I shut the car down. I'd rather not restart it until I'm sure I won't cause (further) damage. Thanks for any help!

Adriano

Might be relevant to add that my idle fluctuated on startup for 30 seconds or so before settling. This was the first time this happened since getting the car several months ago and coincidental with the new tapping noise.

EDIT: I took a chance and restarted the engine. Using the "screwdriver as stethescope" method I couldn't locate the source. It seems to be coming from further inside the engine than the valve covers though... not too sure. The frequency is proportional to RPM.

I can't get the file to play.

Damn this iPhone. I will try to convert it when I get home. It's a loud "tap" "tap" "tap" coming only from the passenger side.

it sounds more like a valve clacking than a tensioner. try to use a long screwdriver placed on your ear and touch various places on the engine with the other end while the engine is running to locate the source of the noise, or use one of those fancy stethoscopes.

I was able to get the file to play with itunes, but couldn't discern what the problem might be. It's definitely noisy - and doesn't sound good.

http://www.amazon.com/MECHANICS-STETHOSCOPE-ENGINE-DIAGNOSTIC-AUTO/dp/B002A1IQ58

I would try this method, under 20$ @ any auto part store

I managed to convert it to mp3: sound clip

Sounds like a noisy rocker arm, pull the covers and check for a backed off tensioner.
eric

Broken valve spring? I only mention it because I had one let go earlier this summer and it sounded similar.

Safe to assume I probably shouldn't drive home?
Should I even start the engine again?

I will consult the bentley/101 projects re: rocker and valve springs, thanks all.

+1

Start at the rocker arms. When you find the loose one check the valve spring for breakage. If you can isolate the ticking to DS or PS you may only need to remove one valve cover to find the culprit.

I would check all of the rocker arms and adjust as needed.

When was the last time you adjusted the valves?

I haven't yet. I realize that should have been first on my to-do list. I've had the car for a couple thousand miles now.

I just read through the 101 projects valve adjust procedure -- by 'tensioner' you mean the retaining nut? Relative novice here so pardon my ignorance. And if it's just the tensioner and not a broken valve spring will this valve adjust set me straight?

That's correct, Mr. Scott.


The big question is why did the nut "back off", if it did. If a valve spring broke, there is no tension on the rocker arm, causing it to be loose.

I'm sure a Pelican is close and maybe could help you with this.EDIT: Just saw that you are in MY.

If you don't know what you are looking for, it will be hard to find. The good news is that it isn't catstrophic.

That IS good news, thanks.

I searched a bunch and from what I gather I shouldn't be able to compress the spring with hand pressure on the rocker.

It's not getting buttoned up until next week anyway since I need to order gaskets, nuts, etc. so I figure I'll go through the valve adjust procedure and if one rocker doesn't feel like the other I'll dig some more.

Solid?

Solid!!:D

:) Seems it would help to isolate the location with a stethoscope -- but is it safe to run the engine?
And thanks for the early morning help, I'm headed over to the parts store now for a 24mm socket.

Just listened to the noise...

It sounds like a broken valve spring to me.

But I can't be 100% sure because it's a recording and it's not in a 3d space.

Can you get to an experienced Porsche mechanic? I hate to be a drag but that may be the best solution.
The experienced Porsche mechanic should be able to tell exactly what it is...

I got part way into the valve adjustment yesterday, aiming to finish it today.

So far nothing seems out of whack:
- Axial play is similar on all rockers
- None can be depressed by hand
- The backside method rocks

I'll inspect all rockers to make sure they haven't wandered off their shafts but I suspect consistent axial play indicates they haven't.

On the driver's side half the exhaust cover nuts came off with the studs so before I did the passenger side I sprayed those nuts with PB blaster, all came off properly.

My exhaust gaskets were an unfamiliar green cardboard-like material.

Turning my fan didn't budge the cam pulley and the belt was already '5 shims' tight, thankfully the 6th shim did the trick but I've ordered a new belt to be safe.

I'll post some good closeup pics before the end of the day in case you all can spot something I can't.

I had an 'admit to your stupidity' moment when I went to remove the 2nd spark plug with the factory tool... thought a rubber boot on the plug itself was kind of odd when I removed the 1st, went to remove the 2nd, uh-oh! no boot! has it fallen?! I poked around with a mirror for a couple minutes before putting 2 and 2 together :)

http://forums.pelicanparts.com/porsche-autocross-track-racing/493886-valve-clearance-smaller-more-hp.html

I'll try to send you a pm w/ a video sound clip of my engine
I think your noise is excessive valve gap.

I couldn't upload the file.

It's amazing how quite a good valve adjustment will sound. Very quite cold, as the engine warms up you will get more sound from the tappets. Did you get a stethoscope? Cheap and a great way to monitor your valve adjustment.

Hi,

Since you didn't find anything out of whack at the valves, I would take off your chain covers and have a look before re-starting. If you lost your tensioner, you could end up with an expensive mess!

Rutager

1+

UPDATE:

Number 5 intake valve (on the passenger side where the noise was coming from) was very loose. I'd been rocking the rockers before setting the gap to get an idea of how off they were -- rocked it a little, felt fine, rocked it harder, whoa, too loose.

Is this indicative of anything? I could have sworn I read that if you can rotate the valve the spring is broken -- can't find the thread though. I can rotate #5 valve but I can rotate the others I've tried as well...

I'm not ignoring the advice about the chain covers but I'd like to take one thing at a time.

I'm going to go through again and check all the gaps, rocker play and valve rotation.

EDIT:
Forgot to mention I realized my feeler gauge was metric. Did some math the convert the backside method:

Gap: .002857" = .07257mm
So GO is .07, NO GO is .08

I compared tolerances in millimeters with the two methods:

.0025" - .003" -> .0635mm - .0762mm -> .0091 (too thin) - .0036 (too thick)
.07mm - .08mm -> .0026 (too thin) - .0074 (too thick)

Seems the metric feeler's more accurate but getting the GO gauge in took some wiggling.

Sounds like you found the problem. I'm suprised you can turn the valve. The clearance on these is very stable so something changed. Could be something stuck under the lip of the vavle holding it open? Could be a bent valve? If you just tighten it and it's staying open you will burn the valve.

-Andy

Andy, That bent valve reminds me of the sound I had several years ago right after a complete rebuild. The machine shop screwed up but the shop that did the rebuild (SC Repair in Houston) made it right and took care of it. 3 years later still runs great and no leaks!

Dug into it some more. Re: valve turning, might not be the valve I'm turning as the rest are just like it, so that seems fine.

I am getting a 'clanging' when I rock the #5 intake rocker that I don't get on the others. I'll upload a sound clip later. Also, I went through all the valves a 2nd time - a few had to be readjusted, so it could be my mistake, but #5 might have been more out of spec than the others.

Would a bent or stuck valve cause the noise in my first post? If not I figure I'll button it up and start it, if the noise is still there I'll have it towed to a mechanic -- if not I'll drive it .

Before you take it to someone else - get a little bit more data. Run a compression check on the engine (I don't show how to do this in the 101 book, but it's in my Engine Rebuild book). There's also an article on the site, I believe (under "Time to Rebuild?").

Valve train noise is generally pretty easy to fix. I wouldn't panic yet. But yes, if there is something that "feels" different about #5, then most likely there is some type of problem with that valve.

It would be my guess that perhaps one of the two springs is broken, and it's not closing all the way. This would cause a leak, and would show up in a compression test. In general, you can't see the inner valve spring, so even if everything looks intact, there may be a problem inside.

-Wayne

Clip of #5 rocker as I rock it back and forth: sound clip
And for reference, the original clip I posted with the engine running: engine noise

They sound similar, so I think I've found my problem.

The 'clanging' happens when the rocker touches the cam, not the valve so does that rule out valve spring and valve trouble? Or must I be mistaken (it was getting late and I was getting tired and I don't have the car with me now.)

Wayne, thanks for the advice. I'll check that article.
And thanks again to all who replied.

EDIT: I just read the tech article, specifically the part about oily plugs -- from what I remember my 4, 5 and 6 plugs were oily indicating "valve guide or piston ring wear" ... Engine had leakdown under 6% cold on all cylinders when I got it a few months ago, maybe some catastrophic failure on that side. Man.

I know it's hard to see the valve springs but can you use a mirror and a flashlight to check them. It should be quite easily to spot one, if any are broken. yeah, the backside method described in tech article is in fractions not metric. Double check the valve lash on # 5

I peeked around with a mirror but I didn't see any valve springs, broken or otherwise. Tried to search for a pic of what I should be looking for, no luck. I'll try again with more light.

Again though, I'm pretty sure the 'clanging' occurs on rocker to cam contact.

that's good, look at the tech article there's pictures of the valve springs, just click on them to enlarge

MrScott,
Did you remove the plugs prior to your valve adjustment?
If so you may have dislodged some crud that may be holding a valve open, throwing
off your valve adustment.
Possibly why #5 was looser then the rest.

I did. Just read that warning in the tech article.
Any suggestions on how to dislodge the crud?

My Bentley doesn't cover crud removal, don't have Waynes book yet, maybe he has a crud removal chapter.
Hopefully someone else will enlighten us.
It's quite possible that #5 is just out of adjustment, as i had one on mine that was out more than the others when i bought it.
Quited things down considerable.
Hope all goes well.

Btw MrScott, where in NY are you? Would be helpful for us to know.

Certainly. I'm in Manhattan -- the car is in Queens.
Having to take a train to your garage slows the process significantly, especially when you forget your keys at home!! :)

UPDATE:

With a mirror I peered into the #5 valve, tough to get my head in the right position with the engine lid in the way but I counted 3 maybe 4 coils which jibes w/the factory spring pelican lists. Top coil was tight against -- whatever it's supposed to be tight against -- valve hat?

I managed to get the suspect valve adjusted consistently; it seemed to me the swivel foot sometimes didn't seat well -- sticking my fingers down and fiddling with it gave consistent readings. This is my first valve adjustment so it could just be a lack of technique. Anyway, play feels normal and movement sounds normal now.

I ordered the gaskets, nuts, etc. from pelican. Going to pick up a compression gauge, button it up and test. Everything seems fine now but a valve going so out of adjustment so quickly doesn't make sense.

Makes sense, but if that's the case I'm no closer to finding the source of the original noise...

fire that bad boy up!!!