Knocking...What to do?

[nebulous123]

I think I have some knocking...sounds like it might be coming from the water pump area from a quick checking. I can hear it best leaning over the top of the driver side fender sticking my ear towards the fan.

I can barely hear it standing in front of the car with the hood up and I almost can't hear it at all from the passenger side (sewing machine is going at it).

When I increase the revs all you can hear is the sewing machine doing its thing.

It a very subtle knock, almost like you would tap on a window and its inconsistent in rhythm, meaning the knock pattern.

The engine idles fine minus the noise, just wondering if this is the beginning of the end or it there is something I can do to prevent it from ruining the engine.

Running 91 octant and this is an ETA motor. Just changed all the belts, entire coolant system and did valve adjustment.

I never got to hear the motor before all the work I did to it because it wasn't running and I didn't notice the knocking till about 3 weeks after I had been driving it around. Its my DD right now and no issues at all just wanted to know what to look out for, ways to prevent problems, etc.

Thanks.

[lateracer]

5 speed? Might be transmission layshaft bearing assembly. That makes a knocking noise

[jlevie]

From your description I'd have to say that you haven't the experience or epertise to be able to diagnose this. And I can't do that without being next to the car. Take the car to a shop and have a pro diagnose the noise.

[CW325]

if it goes away when you press the clutch pedal than it could be the throwout bearing

[nebulous123]

5 speed? Might be transmission layshaft bearing assembly. That makes a knocking noise

would the noise be more prevalent coming from the front of the engine or right near the transmission?

From your description I'd have to say that you haven't the experience or epertise to be able to diagnose this. And I can't do that without being next to the car. Take the car to a shop and have a pro diagnose the noise.

I agree but I figured it wouldn't hurt to ask. I have a guy thats down the street that could give it a listen.

if it goes away when you press the clutch pedal than it could be the throwout bearing

I know that sound you are speaking of, and I have that too. This is separate. Another project another day.

[Cabriolet]

poorly adjusted valves will make the eta sound like a sewing machine.
much worse: timing tension going bad.
pretty bad: broken rocker arm
SOL: rod bearing gone bad. (lower pitched knock)

[nebulous123]

poorly adjusted valves will make the eta sound like a sewing machine.
much worse: timing tension going bad.
pretty bad: broken rocker arm
SOL: rod bearing gone bad. (lower pitched knock)

I did the valve adjustment not too long ago, wouldn't I have seen the broken rocker arm? I just replaced the tensioner. And rod bearing is what I have been reading about and most likely expect it to be. You have any idea the life left?

Just wondering how fast I should be putting together an m50/2 swap for my shell. Have about 8 or 9 months left on the registration. Might ride it out till the end of the that then part it. I will see.

Thanks.

[lateracer]

Layshaft rattle can sorta' sound like it's coming from the engine - my WILD guess is because of the megaphone shape of the trans tunnel and/or the fact that it's mechanically connected to the crankshaft.

I've heard two M20s with rod knocks. They both sounded a little higher pitched than a layshaft bearing rattle (but not as bad as in this video). They also rose/fell with engine speed. Layshaft noise usually goes away off idle.

If it is a rod bearing knock, you can replace the rod bearing without pulling the motor. Might not buy you a whole lot more time on the motor...or it might just go away. Internet diagnosis is spotty at best. Rod bearings make more and more noise as they get worse. Eventually they let go completely. When they do, you're in the market for new everything.

[nebulous123]

Layshaft rattle can sorta' sound like it's coming from the engine - my WILD guess is because of the megaphone shape of the trans tunnel and/or the fact that it's mechanically connected to the crankshaft.

I've heard two M20s with rod knocks. They both sounded a little higher pitched than a layshaft bearing rattle (but not as bad as in this video). They also rose/fell with engine speed. Layshaft noise usually goes away off idle.

If it is a rod bearing knock, you can replace the rod bearing without pulling the motor. Might not buy you a whole lot more time on the motor...or it might just go away. Internet diagnosis is spotty at best. Rod bearings make more and more noise as they get worse. Eventually they let go completely. When they do, you're in the market for new everything.

that video you linked to sounds nothing like what i got going on. that sounds like metal on metal and is very loud and high pitched. this is a low thud that is hard to hear over the engine noise. I am going to make a recording of it and report back.

http://www.youtube.com/watch?v=_qnVA9a-PmM

in case that embed doesn't work.

[lateracer]

An ideal list of video to shoot for interwebz diagnosis:
1) Shot of the car starting from dead-cold (i.e. sitting all night) and warming up at idle. Move camera from top to bottom trying to get good clean audio of the problem if possible. Not too close or the audio will be too loud and distorted.

2) Shot with hood open where car is warmed up and making problem noise. Slowly rev motor to see if knock follows along with RPM range. Same rules for audio.

3) Same shot as above, but with helper pushing clutch pedal.

Good luck

[nebulous123]

An ideal list of video to shoot for interwebz diagnosis:
1) Shot of the car starting from dead-cold (i.e. sitting all night) and warming up at idle. Move camera from top to bottom trying to get good clean audio of the problem if possible. Not too close or the audio will be too loud and distorted.

2) Shot with hood open where car is warmed up and making problem noise. Slowly rev motor to see if knock follows along with RPM range. Same rules for audio.

3) Same shot as above, but with helper pushing clutch pedal.

Good luck

thanks. I uploaded a video for now. but it doesn't seem to be working embedded. I will make another one like you suggested later on this evening. or tomorrow morning.

[PNWDan]

if it goes away when you press the clutch pedal than it could be the throwout bearing

Input shaft bearing not throwout. Throwout would rattle with clutch pressed. If you can hear it under the car and it goes away when the clutch is depressed then its your getrag. Do a search for getrag rattle

[lateracer]

Hmmmm. That might be your water pump or one of the other accessories up front.

As a next step, I might start pulling belts off and then running the motor to see if it's still there.

[E30_fiend]

He said he just did a full cooling system overhaul. Im guessing the waterpump was one of the things that he replaced.

OP, I would start checking the easy things first. Maybe your fan is tapping the shroud or maybe your plastic cover for the distributor cap. Look for any contact points. Pry the fan shroud in the corners and see if you can make the noise worse. Also, you never answered the question as to whether or not the noise changes with the raise of RPMs. Does it get louder, quieter, faster, slower? These are the things we will need to know in order to help you out.


Taylor

[nebulous123]

He said he just did a full cooling system overhaul. Im guessing the waterpump was one of the things that he replaced.

OP, I would start checking the easy things first. Maybe your fan is tapping the shroud or maybe your plastic cover for the distributor cap. Look for any contact points. Pry the fan shroud in the corners and see if you can make the noise worse. Also, you never answered the question as to whether or not the noise changes with the raise of RPMs. Does it get louder, quieter, faster, slower? These are the things we will need to know in order to help you out.


Taylor

sorry about that. gonna go make another video real quick. the noise seems to go away after the revs go up. and whats also weird is when the car is completely cold, i get a little squeal from the belts and I just did them. the PS pulley i have has a minor ding (from PO accident) so it has a minor wobble (looks like it, but is bolted tight) so i thought that might have had something to do with it. However the sound is almost like the water pump is stopping or something causing the belt to squeal then after the engine runs for 5 seconds it stops and never makes the sound again.

VIDEO included... so i noticed some hunting when i was gradually pressing the throttle and I think the knocking was more noticeable after it came down from the revs. also note that the beginning idle and reving was car in neutral and petal depressed (not pressed) after i let off the revs i did a series of clutch in and clutch out prob 10 seconds of each. I cant tell any difference in sound from the video although you can hear a slight difference in the car.

thanks for checking it out guys. i might have a chance to take the accessory belts off and see if the noise is still there. i might also do a video of it making the noise in the morning. we shall see.