Need help: noisy engine after over-rev Options

[DC_neun_vierzehn]

Did you recheck the clearances?

Apologies for the stupid question, but what do you mean? Dumb it down for me pls.

[mepstein]

Just drop the engine and trans.

[930cabman]

Just drop the engine and trans.

(IMG:style_emoticons/default/agree.gif)

[emerygt350]

Did you recheck the clearances?

Apologies for the stupid question, but what do you mean? Dumb it down for me pls.

Valve clearances.

[DC_neun_vierzehn]

Did you recheck the clearances?

Apologies for the stupid question, but what do you mean? Dumb it down for me pls.

Valve clearances.

Thanks for clarifying. Was dealing with a few “clearances” when lowering the engine. Yes, when I put the rocker arm back on C4 I checked/adjusted the valves again.

[emerygt350]

Are you doing .008 and .006?

[DC_neun_vierzehn]

Are you doing .008 and .006?

Correct.

[emerygt350]

When the valves on four are completely compressed does the relationship between them look the same as the relationship on the other cylinders? Does one look less compressed than compared to other cylinders?

[emerygt350]

Truthfully if you have valve train damage you should see that on a vacuum gauge.

https://m.roadkillcustoms.com/diagnose-comm...s-vacuum-gauge/

[DC_neun_vierzehn]

When the valves on four are completely compressed does the relationship between them look the same as the relationship on the other cylinders? Does one look less compressed than compared to other cylinders?

I'll take a look next time I can dive back in. "Completely compressed" = TDC, correct?

[DC_neun_vierzehn]

Truthfully if you have valve train damage you should see that on a vacuum gauge.

https://m.roadkillcustoms.com/diagnose-comm...s-vacuum-gauge/

Thanks for sharing the link. I'll watch those vids to understand the concept. What would be the best place for the vac gauge to connect on my engine (2.0 D-jet) for this test?

[Jack Standz]

You've already got the valve cover off and the rocker arms too. That's the hardest part of removing a pushrod tube with the motor still in the car. Absolutely would not remove the motor and transmission just to check one pushrod. (IMG:style_emoticons/default/smile.gif)

Use whatever version of needle nose pliers you have or these that are currently $4.99 (if you're not liking the possibility of scratching the tube, wrap some electrical tape on the pliers' teeth:

https://www.harborfreight.com/11-in-long-re...iers-64089.html

Where to get pushrod tube o-rings, currently$14.85 for a set of 16 o-rings:

https://914rubber.com/viton-push-rod-seal-kit

[emerygt350]

Truthfully if you have valve train damage you should see that on a vacuum gauge.

https://m.roadkillcustoms.com/diagnose-comm...s-vacuum-gauge/

Thanks for sharing the link. I'll watch those vids to understand the concept. What would be the best place for the vac gauge to connect on my engine (2.0 D-jet) for this test?

I use the vacuum line to the decel.

[rjames]

If you can’t get the pushrod out, it looks to me like you may have enough of it showing to put a short straight edge of some sort against it that would allow you to see if it was bent.

Regarding the difficulty of removing the pushrod tubes, l had to destroy mine with a pair of vice grips to remove them. However, I found new ones pretty cheap at a VW shop so it wasn’t a big deal.

[DC_neun_vierzehn]

So I thought before I attempt to remove the pushrod tubes to pull and inspect the pushrods for bends, I put each cylinder at TDC to remeasure clearance and rock them back and forth by hand to see if they all felt the same. After ensuring all were in spec (.008 for exhaust and .006 for intake) and rocked them by hand, I noticed that the exhaust rocker on C4 felt like it had more play than other rockers despite all being in spec.

So I took a peek at what I wrote down for the clearance measurements when I first dove into this project several weeks ago:

C1 was in spec (.008 exhaust and .006 intake)
C2 was in spec (.008 exhaust and .006 intake)
C3 was out of spec (.004 exhaust and .004 intake)
C4 was the most out of spec (.002 exhaust and .009 intake)

Also, when initially tried to adjust the clearance several weeks ago on the exhaust rocker for C4, it didn't want to budge. I didn't want to break anything so I took the C4 rocker assembly off. I was able to loosen the nut on the adjuster screw with the rocker assembly off, but it took some force to do so. I reinstalled the assembly and adjusted the clearance on that screw to spec (.008).

I removed the assembly again last week while attempting to inspect the push rods, and noticed the adjuster screw on C4 exhaust valve was all the way out from when I adjusted it to be in spec (.008). See pic below.

So my questions are ...

1. Why would the C4 exhaust valve adjuster screw need to be all the way out to get it in spec (.008)?

2. Look at the face of that adjustment screw end - does it look damaged to you (mushroomed or pitted)? Could it be that when I run a flat feeler gauge in there it's measuring in spec, but because it's pitted (from the over-revs?) the clearance is actually greater than what its measuring because of where it's actually making contact?

3. Is this likely cause of the noisy valves since the over-revs?

[Jack Standz]

Looks like a likely suspect. Maybe the valve/seat has sunken in the head?

So, yeah, that's where to invest some time figuring out what might have happened to that part of the valvetrain.

Since you have the rocker arms off and testing is easier, what's the leak down look like on that cylinder?

We run 911 adjusters with modified rocker arms. If you don't want to do that, probably best to invest in some new adjusters too.

[emerygt350]

Interesting! Valve stems stretch but that's a bit much. If it's still out can you remove it and compare to the other one? Compression and vacuum is where I would go if you have it all back together. It's starting to feel like a partial tear down though.... Not at all hard but I would rather not if I didn't have to.

And I don't think the shroom or pits would meaningfully affect your measurements for clearance. Unless it mushroomed after you set it

And... If that is mushroomed, I would be even more inclined to see that pushrod. Those rods are beefy but still....

[tomeric914]

Kris,

The cam in that motor is a Webcam 73 grind. Cam card shows the intake/exhaust clearance is .006" for both. The looser the clearance, the noisier the valve train will be.

I set the clearances using the factory method, which is one cylinder at a time.

Cylinder heads were brand new AA/LNEngineering 914 2.0 3 stud intake heads with 42x36 stainless valves and chromoly retainers

[DC_neun_vierzehn]

Kris,

The cam in that motor is a Webcam 73 grind. Cam card shows the intake/exhaust clearance is .006" for both. The looser the clearance, the noisier the valve train will be.

I set the clearances using the factory method, which is one cylinder at a time.

Cylinder heads were brand new AA/LNEngineering 914 2.0 3 stud intake heads with 42x36 stainless valves and chromoly retainers

Hi Tom. Didn't realize you were on 914 World. Thanks for this info (and the info you relayed to me via Eric on texts and calls over the last month). Per your instructions, I adjusted all valves to .006 (so much easier adjusting both the intake and exhaust at once with the same feeler gauge).

I took it for a short spin and the valves definitely sound less chattery now. I also ordered new adjustment screws and will replace all that look worn once they arrive. It could be paranoia, but I feel like there may still be noise that wasn't there before the over-revs. Could be in my head. I need a fresh set of ears and eyes so I'm going to drive over Rob's place ( @BeatNavy ) sometime soon and let him have a look and listen.

Thanks again to everyone helping me. I'm learning a lot (thanks to my absentmindedness of forgetting to reinstall the damn throttle body spring last Nov).

[Jack Standz]

Would still perform a leak down test, especially on #4 where that suspect adjuster was.

Another possibility is that the adjuster was set with way too much valve lash. If there was too much on that adjuster, it will cause more noise. Also, it might cause the marks on the adjuster face from the excessive pounding.

What's the end of the valve look like for that adjuster?