Loud ticking from Intake valve on cyl #1

[CorvallisBMW]

So i just finished my headgasket the other night (was leaking oil down the side of the block from the oil journal between 3 and 4), and yesterday morning it drove to work perfectly without issue. After a long day I got in to drive home and there's a loud ticking from the front of the engine, sounds like a wickedly out of clearance valve. I get home, pull the valve cover and check all the valves, and they're all perfect. So next I plug the breather hose and fire up the engine so I can look for the noise with the cover off. Using a stethoscope on the rocker retainer, I identify that it's the intake valve/rocker/assy on the #1 cylinder that's making all the noise. But the clearance is perfect. And idea what it could be? It's pretty loud and I'm concerned. Oh and it makes the noise whether the engine is hot or cold, doesn't seem to change. Any ideas? Thanks guys.

Darin

[CorvallisBMW]

This doesn't look right...

Could this have something to do with it?

[noke325]

Eww, not good. Sounds like something is is the cylinder. Something had to break the ceramic off the plug. Unless the ceramic is what causing the noise.

I would get a boroscope and look in that cylinder. Pronto.

[CorvallisBMW]

Spoke to the shop foreman at the dealership, he recommended checking the inner valve spring to see if it broke, and also checking the rocker arm for side-to-side play. If nothing looks out of the ordinary, we have a boroscope I can use to look inside the cylinder.

Update: I spoke with our 2 most senior techs, both of whom own m20 cars. Both pretty much ruled out the broken insulator, they say it would easily break up and blow out. I will take their recommendations and check all the #1 valve train parts for wear though. Underside of the rocker shaft, rocker arm where it hits the valve, etc. Only then, maybe, will I bother with the scope, but it is sounding like that may not help anything at this point.

[CorvallisBMW]

Now with video!!



BTW, checked for any play in the rocker assy an nothing seemed out of whack. Also compression was perfect.

[AndrewBird]

Any chance you could have bent a valve while the head was off? Maybe sitting it down on an open valve?

Does seem unlikely though as the compression figures are fine. If a valve was bent, it wouldn't seal correctly and would throw the compression figures off.

[LowR3V'in]

Hello.
A high mileage crab will have wear marks on the valves making it
impossible to get an accurate reading. It'll have stlight 'U" shape to it so the feeler will be measuring the high points instead of what the rocker is touching.

So.. that rocker tick won't ever go away since the clearance will be too large. You
have no way of knowing what it really is. Or keep getting smaller till it stops?

What people do on the m30 is they use the cam side since that's allot larger and flatter.. It works too. The m20 seems like a bitch to do that way since it's allot smaller but try it out.
Remember there's a ratio on the rockers.

PS. That's a dirty ass crab! j/k :)

[CorvallisBMW]

Ya the head is filthy, PO did not take good care of it. I've been running Mobil 1 for 5 years now, still hasnt cleared any of that varnish.

I anticipated the wear issue on the rocker, so while the engine was running I stuck a 0.003" feeler guage in there to see if the gap was to big. If it had been, that would have quited it down. But it made no difference, so I think the gap is correct. Plus the fact that it started suddenly out of the blue makes me wonder about a wear issue like that being the cause.

[SpecM]

wow that is loud!

if you take lowr3v's advice, make sure you use a plastic feeler gauge!

I would start by replaceing the eccentric

[CorvallisBMW]

So....I figured out what it is. It wasn't the valve at all :facepalm:, though i am surprised my stethoscope led me so far astray.

Turns out that after I did the cam seal and tightened everything down, I must not have gotten the bolt that holds the cam gear on tight enough because it backed out. Because it was loose, the rotor was also loose and was flopping around ever so slightly in the cap and making physical contact with the points on the inside of the cap. That's what was causing all the noise, the rotor was actually striking the points in the cap. I'm surprised the car was even getting spark, the contacts were fucked up! But that's one of the great parts of working at a dealership. I have a parts dept around the corner. So I threw a new cap and rotor on and it's running as good as new. Thank god I didn't have to rebuild a head or something like that.

[supernaughtIX]

holy shit i think this is whats happened to me, im going to check cam gear and rotor right now. I-fucking-dentical noise after a rebuild.

[supernaughtIX]

shit, my cam gear is tight and i put an indicator on it to see that it turns true. so now im looking at my rocker eccentrics and it also look like my fan pulley is rubbing a little on my toothed crank wheel, so ill be working on getting that figured

[Smatt90IS]

glad u figured it out that was the last thing i would have guessed