Engine knocking need help identifing

[dan filipi]

Hmm, I'm thinking what to try next.

Ideas guys?

 

[mcgovern61]

With the spark plug out, there is no compression, but lots of noise from the air escaping. Can you put the plug back in but only about 4 turns to restore compression, but not have so much noise from the air escaping?

What do we know at this point:

*Plug wire off, rockers off, still making noise at higher RPM - eliminates electrical and valve issues
*No noise at idle with rockers removed and valves stationary, plug still in - still has compression
*plug out, appears noise stops (hard to tell from video because of the noise of the air escaping) - no compression, no load on piston or bearings

 

[Jalvarez]

to all: Here is the latest vid. Here again I could not make out the tapping clearly because of the compression from piston 4. I placed a stethoscope and could hear tapping although greatly reduced.

https://youtu.be/xPcUAcC2XWM

 

[89-300ce]

Never mind. I didn't notice the rocker was off.

 

[Jalvarez]

Here is the lastest vid This one with the plug in and as mentioned noise clearly on piston #2
https://youtu.be/vo7CghF1KpY

 

[Jalvarez]

To all: Please disregard post#60 I could not hear the noise because of the compression noise but the tapping was definatively there 83 Knocking with no rockers or spark plug on cyl#2. Noise not present was not correct noise was present

 

[slabghost]

put your thumb on each of the disconnected valves and see if you feel movement. I'm thinking you may have compressed or weak valve springs allowing the valves off seat without rocker push. Then compression even if released through plug hole will still slam the valve seated.

 

[joedrum]

dang ...id take the belts off ...fined the nuetral spot on both heads where cam is free and not on rockers....measure valves spring hieght if they all seem the same if they are ...take all the plugs out and spin it with the starter and listen for noise...might need dowel rod or a listening device to hear it placeing it where you think the noise is ...dont run starter long though ...almost a two person job ...let me refraise that it is a two person job ....

 

[Jalvarez]

slabghost: Remember problem was present before heads were taken of. New machined heads with new valves installed and head verified did the same thing. Different rockers same thing. No rockers on Piston #2 no noise. No rockers on piston #4 noise on piston #3 rockers.

 

[slabghost]

I'm totally out of suggestions now.

 

[joedrum]

i read the whole thread again i think dan might hav nailed it ...sometime the exhast headers will seperate and will flap around like a baseball card on bicycle spooks ...i would still do as i said with the belts off ....slab been listening to the noise and intrurpeting it to me ...if its speratic like he saying that good and probably not lower end ...this is not common on seperating header pipes but it dose happen

 

[Jalvarez]

well this vid after I put everything back after removing the rockers on each side of the head and the noise still there although much less than before.

https://youtu.be/6gt8HlCdPt4

Unless anyone disagrees I will have to pull the engine which was what I wanted to avoid if possible. I guess it not

Thanks to everyone for thier suggestions which were very good and helped me learn much of new ground for me.

I will send you all a message after I pull the block and check the engine.h all of your help I feel more confidwent that it is probably a loose rod. Unless you guys disagree

Let me know your thoughts

Thanks again

 

[Jalvarez]

Joedrum: I already checked the headers and they were good

 

[mcgovern61]

well this vid after I put everything back after removing the rockers on each side of the head and the noise still there although much less than before.

https://youtu.be/6gt8HlCdPt4

Unless anyone disagrees I will have to pull the engine which was what I wanted to avoid if possible. I guess it not

Thanks to everyone for thier suggestions which were very good and helped me learn much of new ground for me.

I will send you all a message after I pull the block and check the engine.h all of your help I feel more confidwent that it is probably a loose rod. Unless you guys disagree

Let me know your thoughts

Thanks again

Before pulling the engine, why not drop the head and check the piston crown for shiney spots? Ya know, I think this sound is very similar to what my '81 engine went through! Bottom line, we think it ultimately was weak springs with the valves floating! The springs measured out of spec and the inner springs were really out.

 

[slabghost]

At this point or probably earlier. If it were mine I'd just run it with the noise.

 

[Jalvarez]

mcgovern61: I can again drop the head and see if the problem is apparent on the back side. However remember this is another head that was put in when the problem first developed. I do have another head that I just got back from the shop.

 

[dan filipi]

well this vid after I put everything back after removing the rockers on each side of the head and the noise still there although much less than before.

https://youtu.be/6gt8HlCdPt4

Unless anyone disagrees I will have to pull the engine which was what I wanted to avoid if possible. I guess it not

Thanks to everyone for thier suggestions which were very good and helped me learn much of new ground for me.

I will send you all a message after I pull the block and check the engine.h all of your help I feel more confidwent that it is probably a loose rod. Unless you guys disagree

Let me know your thoughts

Thanks again

I'd hate for you to split the case only to find nothing is wrong.
I would give it a couple days to think about it and try out any other suggestions that come along. Sometimes ideas will pop into my head in the middle of the night.

 

[mcgovern61]

Simple things to check.....could the timing belt tensioner be bad?? (Just trying to narrow down to simple things). 50K miles on a wing motor is just about the broken in point....not normally bottom end stuff! We must be missing something simple!

 

[dan filipi]

Yeah maybe if it had 200k miles on it, not 50.
True something can come loose of course.

What about while its in gear, still noise?
The trans gears are on the left side, thinkin maybe different gears spin when shifted.

Were all thinking about it and going in deeper with ideas what to look at is always better than not.

 

[mcgovern61]

I listened and watched the video with #2 rockers off, plugs in again. When the tapping begins, it sounds like it is stopped suddenly at idle...as if being closed off??

My '81 exhaust valves were worn down pretty thin, but the inner springs on the exhaust valves were way out of spec (loose/weak/compressed). It might be possible that the inner springs are weak and when you pop the throttle in that video, there is enough vacuum from the piston to pull the exhaust valve in a bit (from the weak spring?). Idle is 950 RPM. At the higher RPMs there is a lot more vacuum and the tapping increases with engine rpm.

(I know this is way out there :shock: ) Maybe try with the #2 rockers off again, spark plug in and see if you can feel movement or tapping on the #1 exhaust valve. (Watch your fingers :shock: )

Just running out of ideas otherwise because everything else points to bigger issues.