Tapping Valves
 

Howdy All..

I am hearing a tapping noise from my 108 4.5. The frequency of the tapping is consistent with the rpm's, and is particularly noticable at highway speeds. Its not very loud, but it is not a pleasant sound.

Of course, I am planning to get this fixed. But, how concerned should I be and how long is it permissable to run the car in this condition? And, what exactly needs to be repaired?

Recent repairs: new vac lines, new points, new cap & rotor.

When were the valves adjusted last?
 

Start there, first.
Also, valve noise is inherent with these valve trains. I've got a 6cyl that almost sounds like a mini-jackhammer. It was probably oil-starved at some point in it's life.

Noisy Valves
 

Is the noise worse on one side of the engine ?
I adjusted my valves yesterday for exactly the same reason as you and hopefully it is cured, my concern was/is that the timing chain is making the noise which is serious if you continue driving.

Gary - don't know when the valves were last adjusted, I am pretty new to this vehicle. I assume that the "repair" that is needed is a valve adjustment. The car has a 100k on it, so a timing chain is probably in order. Would a bad timing chain cause tapping valves though?

And yes, the noise seems to be coming from the left side of the engine.

MunichTaxi - so do you continue to drive the 6 cyl?

It was a $500 car, with little rust
 

Sure, this things are built like a Tank. 'Der Panzerwagen'

Which side is the left side of the engine? If your left is the passenger side, the cam lobes for the first or second cylinder on that bank may have gone South.

Peter

Autozen - it seems like it is coming out of the right side of the engine, the drivers side. I could be wrong though. Still, worn cams sounds like a possibility. I am going to get the valves adjusted after xmas, will know more then. My main concern, since this is my daily driver, is that I might be causing permanent damage.

Tapping Noise
 

If you've got a socket set the cam cover is pretty easy to take off both sides and without doing anything further you might see a broken spring or a retaining spring that has dislodged. The gaskets may need replacing if they are in a bad way if you do this.
Another common problem is that there is an oil feed pipe running across the top of the cam and the plastic clips can harden and break with time starving the cam bearings of oil, again this is easy to see with the cover off.
If you don't feel comfortable doing this and your worried try to minimise your use until you've had in inspected.

GaryF...

I am going to install this kit over the weekend - http://www.**************.com/store/item.php?item=Early%20117%20V8%20Engine%20Valvetrain%20Service%20Kit

Should be a good opportunity to inspect the cams, etc. Can you give me a general idea of what I should be looking for? I probably wouldn't know a worn cam from a new cam.

Tapping
 

Hi,

The kit looks good, I'm not sure if you can replace the chain guides without removing the front engine cover. I could see them with the cam cover removed but couldnt access them very well. Maybe someone else has a better idea on this.

Basically your looking for any pitting or scoring on the cams themselves, checking all of the retaining springs to make sure there fitted ok. These are sort of U shaped metal peices not the valve springs. I've also seen in another post that you should look for different colour metal on the cam lobes, like stripes that indicates the rocker arms are worn.
If you have a feeler guage you can check the gap between the cam and each rocker arm when the cam lob is pointing upwards but unless you have the correct tool you wont be able to carry out any adjustment (don't try it with a normal spanner you'll end up rounding off the nut).

Good luck, let us know how you get on

I wouldn't go through the trouble of changing the rails. You need a puller to get the pins out and you need to remove the alternator and P/S pump. The rails aren't the problem on these cars. The chain stretches and the whipping action will break off part of the inside rail on the left bank( driver's side). This will cause the cam to stop while the pistons keep going up and down which equals bent valves. If you do a search, this topic has been covered. I would pull the covers, replace the oiler hold downs, adjust the valves, and inspect every lobe carefully. Be sure to pull the coil wire from the dist and ground it if you are going to bump theengine over with the starter. Valve seals should be replaced on these engines at around 100 to 125k. If you wait until 150k or more, the valve seals can start riding up and down on the guide and wear the groove so they won't hold a seal anymore.

Good luck,
Peter

Should have mentioned that I'm not going to attempt to replace the timing chain guide rails - I will leave that to an experienced tech when I have the chain replaced. The oiler clips replacement is about as far as my abilities will take me.

So here is the list I am going to take the MB tech:
* Replace timing chaing and guide rails
* Adjust valves
* Replace valve seals
* Inspect cams - replace if necessary
* Inspect rocker arms - replace if necessary

Are there other repairs/adjustments I should have done with this batch?

Thanks for all your help, much appreciated!

If you haven't greased the chassis yet, add that to your list. Here's a 111 chart which more or less mirrors the 108's lube points... Might want to print it up for your tech as there are quite a few.

http://www.w111.net/html/abschmierplan.html