E30 Zone

Managed to spend some time on the car on Sunday and looked into this ticking noise a bit as follows:

With the rocker cover on and the car idling, i used a long screwdriver as a stethoscope to listen in on different parts of the engine. It's really amazing how well this trick works. Anyway, i could clearly hear the injectors ticking away by putting the sharp end on one of them, but i dont think that was the noise i was hearing. I did notice however that the noise was far more evident at the front of the rocker cover than the rear.

With the rocker cover off, i could perhaps see why:





On the No. 1 cylinder cam lobe for the inlet, you can clearly see it's worn already. That was a brand new cam no more than 1000 miles ago! The thing that mystifies me still though is that i had this noise before i changed the head/cam/rockers, so perhaps this isn't my problem. The rockers came with the second-hand head that had previously been used with the exact same type of cam that i've used, so there shouldn't have been a problem.

Any ideas or suggestions?

Funnily enough, the car is a little less noisy now, but i changed the injectors and changed from fully synthetic to semi-synthetic oil (Castrol Magnatec) so perhaps they could have contributed to it.

Hmmm, I seem to be suffering the same tapping after my head rebuild too and I'm starting to think top end........
BTW - I can't see any 'wear' on the cam lobe, you'll get that scratchy look after the engine had been running for half an hour after the rebuild.

I don't hold the answer to this problem I am afraid, but I am curious to know the outcome... Does this make this noise when the engine is worm as well ???

Jose

Are the rocker shaft's straight ?

Would it make a difference if you rotated them by 180 degrees ?
Paint a mark on them and see if they work there way back to where they are now.

I was wondering if the wear on the photo (the shiny bit on the lobe) was normal or not.

How could you rotate the rocker shafts? I suppose you might be able to grip onto them with some mole-grips and turn them perhaps?

I'll just keep an eye on it and see what happens.

my motor started making a really bad ticking, and i narrowed it down to the injectors(i hope). I used a long screwdriver too, and it sounded like the #4 and 5 injectors were really loud. Now my car is running on 5 cyls and I think thats my problem. I checked the rockers and everything else, and it was all normal.

I'll be changing my injectors soon, so hopefully thats the noise.

if you can, try changing them and see if that helps.

Kyle

I've never managed to cure mine completly and just live with it
I'd still like to shut the thing up though
Pete did you check the block was dead level before the head went on?
I'm wondering if its due to the head twisting slightly once it's bolted down and the noise being transfered through the shafts where they make the tightest contact with the head.

As for the cam lobe in the pic, that looks to me like it's just bedding in.
Wear would show as a groove (so i've read) (on here)

I would have thought that if the rockers were stressed due to microscopic twisting this would have happened as the head was tightened down and susequently adjusted during the valve clearance setting. If the shaft is 'twisted' so to speak, it will be unable to rotate, surely?

Having said that, if you haven't re-checked your valve clearances since the rebuild, you should, as the bedding in will open the gaps.

The tappets were set after the head was put on, but i guess it's probably worth doing them again now that the engine has done a good few hundred miles since.

I didn't check the block was level - the head was taken off/put on by the garage so i doubt they will have checked.

How do you adjust the tappets?

oze30 wrote:How do you adjust the tappets?

look in the articles section at the top mate, technical section

First off the M20 top end invariably ticks, they just do.

If the top end has recently been re-built it will be worth re-checking/setting the clearances - make sure you do this with the engine stone cold.

Also I could read your post as indicating that a worn cam has been used with a different set of worn followers, if so...

A cam and followers should always be treated as a set and not mixed up once they have seen some use, ie take care to install the same follower to the same cam lobe.

A new cam allways needs new followers and the same is true for a worn/used cam if the original matching followrs are not available. Its not the end of the world if you have used a worn cam and non-matching worn followers but it will make more top-end noise and be more difficult to adjust accurately.

Welcombe to the zone, Apal, your advice is spot on.
Rocker shafts are located and prevented from turning by a locking plate that fits into slots in the rocker shafts at the front of the head.
If your head has been warped and skimmed, neither the rocker shafts or the cam will be running straight. They will still be bent by as much as the head was.

Ive looked in the section above.. but nothing on tappets. Only valves. What can I do to adjust the tappets are they are LOUD!!

oze30 wrote:Ive looked in the section above.. but nothing on tappets. Only valves. What can I do to adjust the tappets are they are LOUD!!

Take a look at the Articles section of this website - there's an excellent page in there telling you exactly how to set up the tappets.

oze30 wrote:Ive looked in the section above.. but nothing on tappets. Only valves. What can I do to adjust the tappets are they are LOUD!!

The valve adjustment article is the one you need, it's mis-described really as you can't adjust the valves

Cheers,

Iain T

So what your saying is.. the tappet sound will disappear ( hopefully) if I redo the valve clearances?? So no tappets, but valve noise!?!?

It won't go away completely, all M20 engines make a little tappet noise but it will almost certainly make it better.

Cheers,

Iain T