Need help with engine noise
 

Hi. I have to apologize for the continuous engine noise threads but this is a little different than my last one.

Before I had a loud tick on bank 4,5,6 and found out the valve adjustment screw came loose. Fixed that and all was good.

Next day, bank 1,2,3 started making this awful knocking sound. (YouTube link below)

https://youtube.com/shorts/WjcJrKGx88s?feature=share

I have the valve covers off and I have to push really freaking hard with a piece of wood to push in the valve spring so I don’t think any is broken.

The rocker arm bushings are all good and none have walked. They’re all super tight.

All valves are adjusted properly (used SnapGap so I know the gaps are right).

Car smokes on start up, but not when decelerating from high RPMs

Question 1) if I had a broken valve spring, how hard would I have to push in to compress it?

Question 2) how can I check for worn valves guides without driving the car?

If you have any ideas please please let me know. The last shop never got back to me and I’m on a tight budget.
I just want to enjoy the car (lol)

https://uploads.tapatalk-cdn.com/202...932403f18a.jpg

Air-Cooled Porsche 911, slant nose modified no less, and a tight budget don't go together. That noise is bad. Check for exhaust leaks. You probably should localize the noise a little more using a hose or a stethoscope to see where the noise is coming from. Exhaust or intake. Which cylinder? Cam shaft, head, or cylinder. I think more diagnostic is needed.

Unfortunately, that’s how it is sometimes.
I used a long screw driver as a stethoscope and it really sounded like it was coming from either cylinder 2 or 3 exhaust side, but it’s really hard to narrow it down.

Is it a really bad idea to run the car for a few seconds with the valve covers off to narrow it down ?
I already have plastic on the heat exchangers to keep oil off them

I would give all the rockers s good shake when they are on tdc fire. I know you said they are adjusted properly though. The noise certainly seems 1/2 engine speed pointing towards valve train. You could also pull one plug wire at a time while it’s running to see if the noise changes on a particular cyl.

Would not recommend running it without valve covers but hey I’ve never done it. Let us know what you find.

Daniel

Need help with engine noise
 

Each rocker from each cylinder at tdc clack when moved side to side. It’s more of a click when pulled forwards and backwards which seems normal due to the valve gaps.
I’ve read on this forum that side to side play on the rocker arms usually have nothing to do with valve train noise unless they are super loose.

I’ll try the plug wire trick when I put it back together.

For now, I’m trying to do as much troubleshooting as I can with the valve covers off

Check all head studs and they’re all tight.

I rocked the valve stem in a vertical motion on cylinder 3 and there is some movement.
Worn valve guide may be the problem.

I’ll continue troubleshooting

https://uploads.tapatalk-cdn.com/202...4ba9790bd1.jpg

i hear broken valve spring...i would not
drive it...i just posted what could happen to you ..driving with one broken spring in Bohemia and 911.
If the engine is smoking cold or morning that would your valve guides.You should do a leakdown test..

Ivan

I see an engine drop and valve job disassembly in your future.

Are you absolutely 100 percent certain that you don't have one valve out of adjustment? In checking this, did you go around the firing order and make certain all of the valve clearances are correct?

All the valve springs seem super stiff. I have to push down on the rocker really hard with a piece of wood to compress the them, so there’s definitely no signs of a broken spring. Is there any other way to check?

It definitely smokes on start up so guides it may be

Yes. It’s really hard to get them wrong with the snapgap kit. To me, the noise is more clunky than a valve tap so I don’t think a loose valve would make this kind of noise

on the pic number 3 i cannot see the end of the rocker shaft?? is it in the right position ??it has to be on all of them to the thinner bore
http://forums.pelicanparts.com/uploa...1653062361.jpg
http://forums.pelicanparts.com/uploa...1653062421.jpg

if you certain about the springs, valve guides it is...
Ivan

Here’s a better picture. They all are flush-ish on the right side of the bore
https://uploads.tapatalk-cdn.com/202...8f2e0e71f3.jpg

ok good;-)
still be careful of high rpm if you drive it...
Ivan

This is what Tony had us looking for when setting the rocker shafts - just a hint of shaft at the thin side aperture.

http://forums.pelicanparts.com/uploa...1653082849.jpg

Like Ivan, I dont see that in the upper photo of the #3 exh, so maybe it did "walk," or is it just missing the nut? In the lower photo the angle can be deceiving, so leaving that speculation until further evidence.

Valve Spring Inspection.........
 

Winter,

You need to use the P7E and P7I tools to remove and inspect the valve springs with the motor installed in the car. It takes only a minute or two to remove the valve springs per valve. Inspect them and re-install them back. Go to the next valve. The procedure is like doing a valve adjustment @ TDC for each cylinder.

You can not guarantee that all your valve springs are good and intact without further inspection specially the smaller interior springs. PM me if you need to borrow the P7E/P7I tools.

Tony

P7E & P7I Tools.......
 

What year is the engine? Could one cyl head have lost it's air injection plug near the exhaust port?
Would make a similar sound. A loud tap that speeds up as engine speeds up
Just a thought.

Thank you to Tony, I really appreciate that. I put the car back together for now, but I may reach out in the near future for those tools.
Definitely before I drop the motor and rebuild the heads
Thanks again.

https://uploads.tapatalk-cdn.com/202...4c9847ef15.jpg
Mine are only flush of the right side (5mm) The 8mm is inside the bore


Sent from my iPhone using Tapatalk

It’s a 2.4 MFI from 1973

Yes, that photo better shows where the 5mm nut is and looks spot on...

UPDATE:
Okay… the noise continues and at this point it’s getting unbearable. I took the intake valve covers back apart and the rocker arm on #3 at TDC makes quite a loud metal sound when rocking it side to side. Here’s a video:

https://youtube.com/shorts/2kfM0LkDcSY?feature=share

Could this be the culprit? I checked the rocker bushing bolts and they are FREAKING TIGHT.. so I don’t think it’s loose. Valve clearance seems just right also.

Is this noise normal? Too loud?
If the bushing bolts are tight, how else can I tighten the rocker arm?

Here are few pictures:

https://uploads.tapatalk-cdn.com/202...818a19b37c.jpg
https://uploads.tapatalk-cdn.com/202...e36031362e.jpg

From that latest video it appears that the rocker arm bushing has failed, or the shaft has. There shouldn't be that much rotational movement.

There should be a detail in the spec book indicating the limit of side to side movement.

at this point you should remove the no 3 rocker shaft and inspect it for crack.
ivan

Update:
The search still continues... Noise is still there.
The side to side movement on the rocker has nothing to do with the noise I'm hearing.

Can a worn valve guide really make this kind of noise? Car doesn't really smoke and I'm unsure on how much oil it burns.

Someone suggested it could an exhaust leak but it sounds more like a metal to metal noise.
I will take it the valve covers off once again to see.
I did narrow it down to either cylinder 3 or cylinder 2.

do the valve adjustment again. It's easy to screw up as you turn the engine looking for TDC on each cylinder.

A few things that have already been suggested First of all, go around and check all the valve gaps again, then I would pull each spark plug in order to determine whether the noise gets less, as for smoke on start up, this is often down to oil collecting in the crankcase from the oil tank over a period of time, seeping past the piston rings...Valve guides and valve stem oil seal issues usually show up on the over run, as oil from the rocker cases gets drawn past the worn valve guide seals and into the cylinders via the valves.
Someone else mentioned the noise could be coming from an exhaust manifold problem, or could be a broken head stud, its a possibility, but it does sound more like a mechanical noise, I also wonder if you may have a valve that is sticking, this could be caused by over revving the engine at some point, and a valve is slightly bent.
There are quite a few thoughts on this thread already, and you seem to have checked most of them, just a few thoughts of my own added.
A...:)

Any update on this ???SmileWavy

My thought as well. I've done dozens of valve adjustments on many types of engines and still managed to screw up my 911 adjustment once, must have been at the wrong TDC. Noise was exactly as your first video.

I dont think it's the gap, its the side to side limit; either the rocker arm bushing is worn out, or the pin is, or both. In the video the click is most prominent when sliding back and forth, not up and down https://youtube.com/shorts/2kfM0LkDcSY?feature=share

Just check the rocker arm by turning the engine to TDC take out the shaft and then the rocker! check to see inside the bushing to see what it looks like !..I checked mine and i had to replace a shaft!..

while you have the shaft and rocker off place the shaft inside the bushing and try and move it back and forth while holding the rocker and shaft!..if theirs play then that's your answer!

I have same issue with the side by side rocker movement!..But i'm pretty sure its the bushings!

I will be taking my rockers off and sending them to the shop soon but i just want to make sure first!

Need help with engine noise
 

Update:

Hi all, I appreciate all the recommendations.

I pulled the valve covers yesterday and adjusted the valves once again. Re-Adjusted them all with the backside method and with the .004 clearance.
The valves should be dialed in.

I also pulled each spark plug wire to isolate the noise to a cylinder and the noise did not go away.

Here are the unfortunate news. The noise is still there..
Car runs good and no smoke.
Can an injector make a noise like this? I’ve read several people talking about loud injectors.
I put my stethoscope to injector #3 and it’s definitely really loud… louder than the others.
It’s hard to tell if that’s the source of the problem

I’ve never heard of a rocker bushing shaft getting worn out, or making this noise.
It’s a really good possibility since I didn’t consider it.

I guess I’ll have to take out the valve covers once again (lol). These silicone gaskets are really not having a good time.

Can this be done with the motor still in the car?
Noise is near cylinder number 3 and I’m not sure if the bushing can be removed without tapping it out with something.

Was yours making a similar noise before you took it apart?

The rocker and shaft can be removed with the engine in but clearance will be a headache. From the looks of it your biggest enemy might end up being corrosion in the shaft bores. The shaft might take some wallops for you to get it out and the angle will be difficult engine in.

Yes, they do, which is why when folks rebuild their engines the rocker arms often get rebushed. There will be a Porsche spec on this for max. wear diameter before needing to be machined and bushed.

One of the joys of our passion....

@Winter911

Did it end up being the rocker bushing?

@LBEEMING I honestly never figured it out. I adjusted the valves once again and it did get just slightly quieter but that dreading noise was still there.

An porsche engine guru told me that side to side movements on the rocker arm is normal (up to a point) and would not cause that kind of sound.

I did a leak down test and i got less than 5% on all cylinders so no loose valves or broken rings.

I did put a stethoscope to each MFI fuel line and it almost sounds like it might be an injector getting old... and since these things are mechanical they're super clicky and loud. Car pulls super strong and doesn't smoke.