A curious noise coming from an overhauled engine

[watson2]

Hi guys . Thank you for your help.
I hope this helps to understand why i define this noise curious…

https://www.dropbox.com/s/lj07ul6omk1qqdh/Engine_noise.m4v?dl=0

Please wait some seconds while loading.
Now it seems a bad, bad noise, when present.

Monday morning the engine will be opened again  (sic)
I will let you know the results

P.S. ...but if you have any idea , please tell me…

[stickandrudderman]

That's a tappet noise.
Do you get an associate misfire when that noise is present? If so then you have a sticking/bent valve or loose seat.
If no misfire then it's probably a fatigued anti-rattle spring (or incorrectly fitted) of less likely a worn tappet post.
Either way it doesn't sound as serious as first thought.

[ja17]

Yes, most likely a valve train problem. Loose valve seat, or guide and/or bent valve. You may even notice one spring assembly sitting lower when you remove the valve cover.

[Benz Dr.]

Going on what Chuck said, it could be a broken roto cap. It sticks in one spot and then lts go causing noise for a while until it locks p again. You could remove the rockers on that cylinder and  tap the valve retainer which will make the valve spin. If it doesn't turn or it stops turning that could be the problem.

[watson2]

That's a tappet noise.
Do you get an associate misfire when that noise is present? If so then you have a sticking/bent valve or loose seat.
If no misfire then it's probably a fatigued anti-rattle spring (or incorrectly fitted) of less likely a worn tappet post.
Either way it doesn't sound as serious as first thought.

Hi Stick .
I thank you for your post. No misfire at all. Someone told that the engine seemed rough when the noise is present, but I never heard directly this.
The valves have been buffed (I hope that this is the exact word in english) and , as you can see in the previous page in my message nr.3, the rockers arms , screws and balls are new.
The valve guides are new and verified
Using the attached image , please, can you indicate the number corresponding to the anti-rattle spring  and to the tappet post ?

 

[watson2]

Going on what Chuck said, it could be a broken roto cap. It sticks in one spot and then lts go causing noise for a while until it locks p again. You could remove the rockers on that cylinder and  tap the valve retainer which will make the valve spin. If it doesn't turn or it stops turning that could be the problem.

Excuse me Benz Dr. , but my english , above all the technical one, isn't good enough to understand a lot of terms. Looking at my posted image , which number has the roto cap?
And the valve retainer is the nr.82 ?

Thank you for yo help

[Cees Klumper]

Roto cap (essentially a bearing) is no 73 and valve retainers no. 82.

[Benz Dr.]

The roto cap or rotator cap is a device that makes the valve spin as it moves up and own. I believe there are a number of ball bearings inside and a series of notches that the balls fit into that allows movement only in one direction. If you remove the oil fill cap on a running engine you can actually see the valve retainer slowly turning at idle speed which means the roto cap is working on that valve. I check them during a head rebuild by tapping on the retainer which should make the valve spin. I've seen them bind up and quit working possibly due to wear or rust from prolonged storage.

If you can locate which cylinder is causing the noise you may be able to do the test I suggested.

 

[Cees Klumper]

Using the attached image , please, can you indicate the number corresponding to the anti-rattle spring  and to the tappet post ?

I guess anti-rattle spring is no 94 and tappet post no 92.

[stickandrudderman]

Cees wins!

[ja17]

Any news on the engine noise?

[watson2]

Hi guys. I was waiting for results.
The engine has been deeply inspected and the only thing that has been found is an augmented play of one of the  valves of the cilinder nr.6 in its giude.
So the remedy put in place in an attempt to eliminate the noise has been a new set of 12 valve guides; as a matter of fact during the overhaul they changed the valve seats but not the guides. 
Just tomorrow  morning reassembly of the engine will be started.  I will let you know when the key will be turned...

 

[stickandrudderman]

An engine overhaul that didn't involve new valve guides?

[ja17]

Double check the valve seats. Valve guides do not normally make noise when they go bad.

[watson2]

An engine overhaul that didn't involve new valve guides?

When I knew this I was amazed as much as you.
Look at my msg....

[watson2]

Hi guys. Here we are. The engine was finally started and , at this moment, has done about 400 Km. The sounds you heared are gone, but I can not say that it is perfectly silent. There remains a slight background noise that could depend by the play of the valves.
But I'm afraid that it could depend on the compression ratio.
Even if the piston have been reduced on their head for 5/10 of mm. the value of the compression remained high (about 10:1 in comparison with the original value of 9:3).
I examined the image of the head of another car (a 280 Sl, I suppose) and you can see it as the first one of the 3.
The second image belongs to my engine before any work.
The third one is always the head of my engine , but after grinding works. (correct term?)
What do you think about this last aspect of the matter?
Have to look for a new head? Do you think that gaskets with increased thickness could represent a good remedy?

[Cees Klumper]

To my untrained eye it would seem too much of the head was removed (I believe the term is 'skimming'). The shape of the combustion chamber is quite different from before.

[jpinet]

I would concur with Cees. They seemed to have removed way too much metal form the head. If I see correctly, the exhaust valve is out of the combustion chamber.

[ja17]

May just be an optical illusion.  Measure the thickness of the head to be sure. The ends seem to get cut the most.

[watson2]

The flame front propagates in every way 'cause the roof of the piston has been turned. In this way the path of the flame isn't certainly the one of the project. My consolation is that I see on the german site of SLS-hh that they use in their e-shop an image like mine to show the piece in question. 
I asked to the technician and he said the the height of the head is within tollerance.
Anyway I'll begin to look for a new head....

The engine has an uncertain idle and we found the spark plugs in this situation.
The spark plugs are from 1 to 6 from left to right. Every cylinder is linked to the corresponding spark plug. The  cylinder 1 has a dirty spark plug, but the piston head quite clean  while other cylinders have the spark plugs clean but the heads of the pistons encrusted. What do you think? Have I to change injectors? They suggested to me to change all the injectors. To avoid to throw away money...  sure all?

 

[tel76]

You say your mechanic says the head is within tolerance, what cylinder head thickness is he using?
You could move the injectors into different cylinders to see if the pattern repeats itself, or get the injectors tested on the correct machine.
Also you could purchase a burette and see if all your combustion chambers are equal and with this information calculate your compression ratio.
I have the (standard) volume of the combustion chamber of the type of cylinder head that you have, if you decide to go down that route.

[GGR]

Watson, how did you determine you now have a 10:1 compression ratio?

[ctaylor738]

I would say that you have a problem with injector #1, and that you are running a bit lean.  I would go two clicks rich on the rack, and adjust the idle mix as needed.

Autohausaz.com has injectors for $103 apiece, and offers discounted international shipping.

Good luck.

[watson2]

Hi guys. Excuse my absence.
@tel76 : my mechanic has a  table with all standard measures of the parts of the engine. I refer what he said and I have to trust what he says.
We calculated a volume for the 230, in original conditions, of 41,2 cc. (about 2,5 cubic inches) . Is it correct?

@GGR : the mechanic showed to me a pink chart done with the usual little tool made to measure the ratio.
I think that the value is not too high, all things considered, for the 5/10 lowering of the pistons; with this value we regained 2,67 cc (0,162 cubic inches)

@ctaylor738 : I am in accordance with you and so we are waiting for new injectors (Bosch 437 004 002) . We found for 87,5€ incl.tax in Frankfurt at Partsrunner.


News as soon as possible.

[watson2]

Hi guys.The injector nr.1 has been changed. This is the plug nr.1 .  Now the engine runs much better, no bang, no uncertain idle. But it still remains noisy,  especially accelerating during normal use . It's not the noise I heard on other 042 engines. I observe with suspicion the head....