Clattering noise from cam housing

[Tanz]

My engine makes an awful clattering sound from the cam shafts particularly when cold. It still makes the noise when hot but 50% less. I have removed the hydraulic tappets and cleaned them, refilled with oil following the service notes and the video on Elan Central - twice - but no improvement. I have measured the cams but they are well in spec.
With the cam cover off and turning the engine by hand there are no gaps between tappet bucket and cam lobe i.e. I can't get my thinnest feeler gauge between them so that is correct as there should not be a gap.
Could it be a lack of oil reaching the tappets? Oil pressure when cold is just over 5 bar.
Bent Cams?

Here is a video so you can hear the noise: https://youtu.be/QaKpOQkAMbE

I have no idea what is causing this so any help appreciated.

[steve matthews]

CAS has a pin pull cover and check?
Steve

[HJ2]

I'm with STeve.
Either a broken pin in the CAS coupling (or broken spring)
Or: failed bearings. These are pretty standard and easy to change.

[Tanz]

Thanks for the replies - I will investigate and let you know.

If anyone has any other ideas to add to the list of thing to check please say.

[Hector2021]

Have you tried with a listening rod to your ear to locate the exact area the sound is coming from?

[muley]

...and if you don't have a listening rod, just use a screwdriver

[HJ2]

A listening tod(dler)? That is impossible

[lotustonybassplayer]

Mine has pretty much the same noise, I did change the CAS, as i had found the pin had been replaced with a drill bit. however i still get the noise i recently changed the bearings in the CAS and it made no real difference either its been like it pretty much since i have had the car for 12 years ! i seem to remember somewhere that someone mentioned if the cam belt isnt tensioned correctly it can cause some sort of fluttering.

[chris]

I had a similar issue when i replaced the thin sheet metal heat deflectors over the exhaust manifold and turbo components ...... if they are not fully tightened and compressing the shield they can make an awful racket when they resonate !

I did happen to notice that your heat shield screws are not the original flanged hex heads so could they have been replaced and not fully tightened or loosened off ?

An easy check in the first instance before you start pulling the engine apart.

Let us know how you get on.

[Tanz]

Have you tried with a listening rod to your ear to locate the exact area the sound is coming from?

I used a screw driver and the noise was loudest when I put it on the metal flange of the CAS where it meets the cam housing. But when you stand back and listen, the noise seems to come from inside the cam housing so I guess the noise could be transmitted from the cam to the CAS

[Tanz]

Thanks again for the answers - keep any thoughts coming.
My plan of action is to remove the CAS and see if I can determine if there is a problem with it. Then have a look in the turbo area. I did listen to the turbo with a screw driver but sounded ok. I guess a process of elimination is the best way forward.

[peteoddcar]

Did it suddenly start or gradually get worse?
I had a whirring noise with my car after a cam belt and water pump change and that sounded like it was from around the CAS. The CAS plastic cover acts a sound box.
After a lot of fiddling and trying different diagnostics it appears it was a bad water pump drive gear.I sort of had to be something to do with the cam belt job as it was fine before.
It’s quite easy to check the CAS drive to eliminate or fix, I think if that all looks good then take a look at the cam belt tension - follow the procedure to check and set in the Wikilec.

[Tanz]

Did it suddenly start or gradually get worse?
I had a whirring noise with my car after a cam belt and water pump change and that sounded like it was from around the CAS. The CAS plastic cover acts a sound box.
After a lot of fiddling and trying different diagnostics it appears it was a bad water pump drive gear.I sort of had to be something to do with the cam belt job as it was fine before.
It’s quite easy to check the CAS drive to eliminate or fix, I think if that all looks good then take a look at the cam belt tension - follow the procedure to check and set in the Wikilec.

When I got the car I towed it home and the first job was a cambelt change. The water pump felt OK so I didn't change the pump - so you might be onto something. I will add it to the list - thanks

[Simon_P]

i seem to remember somewhere that someone mentioned if the cam belt isnt tensioned correctly it can cause some sort of fluttering.

If the belt is loose the CAS rattles it will get less bad as the engine warms as the expansion tensions the belt. There are different tensions for used and new belts and the 60 degrees atdc (Crank) is important.

[peteoddcar]

Setting the tension with the engine at 60 degrees is very important.

[Tanz]

Do you guys actually use a 10kg weight or just finger pressure

[peteoddcar]

Look at my post in engine ‘ Is my cam belt fitted the wrong way round ? ) and the wonderful responses
It should help

[Simon_P]

Do you guys actually use a 10kg weight or just finger pressure

a finger calibrated beforehand by pressing down on some scales and a steel rule with tape on it which sits behind the belt

[Tanz]

Got round to looking into this today. I checked the cam belt tension (after the usual battle with the upper cover). Used a protractor to set the crank pulley at 60 degrees after top dead centre, stuck a ruler to the cam housing and even tapped a nail to the belt as a pointer (a bit over the top I know). With firm finger pressure it is in spec for a used belt.
So I moved my attention to the CAS. Removed it from the car but couldn't find anything wrong with it. No play in the pin, spring seemed good. I was just about to refit it and I looked at the end of the cam to see where the off-set dogs were and I noticed that the end of the cam appeared to be damaged - see pictures below:



A small piece seems to be missing from the corner of one of the slots

More pictures and video below.


https://youtu.be/DhQlDCGlHh8

https://youtu.be/OZNzM_WXx54

[Tanz]

OK. Finally got to the bottom of this. Everyone who had a listen to my engine (including a couple of M100 owners) seemed to think the noise was coming from the CAS end of the engine and I agreed. I borrowed a good CAS and tried it but that made no difference at all - still very noisy. So at least that eliminated the CAS. I disregarded the tappets as they had been cleaned and refilled with oil - twice! So the other moving parts are water pump, idler bearing and tensioner. When I replaced the cam belt a couple of years ago they felt OK so I didn't change them - big mistake. After removing the 3 parts mentioned above the tensioner and Idler were a little noisy when spun in my hand so I guess would be worse when under load. The water pump seemed OK but I didn't want to make the same mistake twice so ordered all 3 parts plus a new cam belt from Rock auto. Now fitted and all is quite.
So the lesson to be learned (by me anyway) is when changing the cambelt every five years change everything else as well!
What threw me was how the noise transmitted through the engine and didn't sound as if it came from the source.