I had a similar tick, ended up removing the cruise control actuator. Although yours sounds just bit louder.

__________________
Onus probandi incumbit ei qui dicit, non ei qui negat

I recondition w123/w126/w124/w140/r107/r129/ steering boxes!


1984 300D "Elsa" odo reset 6/2011 147k
1983 300TD "Mitzi" ~268k OM603 powered
1995 E300 "Adelheid" 262k [Sold]

Drove it 300 miles today... ran great, most the trip i was on cruise control doing 70, at some points I hit 90 just to see.... I verified the speedo was correct using my gps.

Before I left I noticed a new A/C belt in the trunk, so I tossed it on, charged the system, swapped the kilma from my 300CD and got cold air. The tach does not work. there are a few times I noticed it try to work when I would really kick it down. The trip including 4 different mountain climbs, some city driving etc... really a taxing trip on the car, but not an issue. So, whatever this knocking is it does not seem to be effecting the car. I did have the car run for a second without the power steering pump hooked up, so I can rule that out. THe A/C compressors tight, since I just did that. When I put my stethoscope right in the alternator, it sounds fine... so I'm ruling that out.

This has stumped multiple mechanics, so I'm not going to feel to bad if I can't figure it out, but It would be a nice feather in the cap...

Just as a last check have you looked at the engine mounts and the trans cooler lines? I know a friend of mine had the mount heat sheilds bent and they ticked when the engine was running, I forgot what they were hitting.

__________________
Onus probandi incumbit ei qui dicit, non ei qui negat

I recondition w123/w126/w124/w140/r107/r129/ steering boxes!


1984 300D "Elsa" odo reset 6/2011 147k
1983 300TD "Mitzi" ~268k OM603 powered
1995 E300 "Adelheid" 262k [Sold]

My cruise control actuator was clicking also, but not quite that loud. When I put my had on it I could feel the sound.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

I've come to determine that the noise is loudest in the front of the engine, piston 1. I pulled off the valve cover again to take a closer look. There appears to be a fine "sand of metal shavings mixed in with the residue oil in the cover. My best guess here it that although this engine is performing well, not smoking, and seems to have plenty of power that there is an issue with piston 1. Might look into rebuilding the engine, but it would be a real learning curve... Looking for another engine to stick in there for now and might just go ahead an grab the one out of my CD. I have to take that engine out of the CD anyways to repaint the car so no real extra work. I would like to fined a nice low milage engine to put back in.

Your sound is exactly one-half engine idle speed. So, the noise is probably restricted to the camshaft or the injection sequence.

The noise is a metallic tap, therefore I'd discount the injectors as the source.

I'd take a closer look at the camshaft and lifters before doing anything else to the engine. It would be hard to condemn the #1 piston if the noise is not repeating at engine speed. It could, of course, be contacting a valve...........which might become obvious if the valves are way out of adjustment.

First thing I did was go in and adjust the valves thinking the same thing. no change. cracking each injector made no difference, except to show me that each was working fine.

The fine sandy texture of metallic particles i'm seeing in the valve cover does lead me to believe that whatever is the problem is causing a good amount of engine wear someplace. I think the best approach is to locate a good donor engine and swap. Then, I can take this engine and tear into it and see what the real story was.

Someone around me should have a good motor sitting in a crappy rusted out car, plus I could use some other parts off one, like a piece of rear quarter glass for the the back passenger door...

If I get into the engine and find It's a simple fix at that point, then I have a spare

What does get me is that even with this noise and the particles, the engines is not smoking and is showing very little blow by.

Is there any way for me to check the timing chain without having that special tool? if not, is there a place to get that tool cheap? maybe even used? Since I'm up to 4 of these right now maybe it would be time to start tooling up for them.

Also, does anyone offer a rebuild kit? whats the best approach to a rebuild? Some of the rebuild numbers I have seen on here seem way out of line with the value of the car.

You find metallic particles under the valve cover, presumably caused by the camshaft and/or lifters and you have determined that you want to "tear into it" to locate a problem inside the cylinders?

I've already told you that the tapping is exactly one-half engine speed.........thereby directing your efforts toward the camshaft or the injection system. You've properly ruled out the injection system.

You're baffled by the fact that the engine runs well with no smoke and little blowby although the engine is trying to tell you that its cylinders are fine and the issue is with the valve train in some fashion.

You remind me of most doctors who tell you your problem before the exam is complete and a careful analysis of the tests and symptoms is performed.

No, I'm just assuming that since I see that sandy stuff, the damage most likely as already been done. I ran the car yesterday without the valve cover on... messy, but I didn't see any issue. The cam itself looks perfect. no noticeable wear on ay of the lobes. I also hand turned the engine and checked every link in the timing chain, plus looked for anything that might be in there and making the noise.

In looking at this diagram,

I see wear on the end of the part I circled and labeled 1. On the part I circled and labeled 2, I noticed that the "shaft" does not line up with it's counterpart, allowing the main part to from side to side (front to back on the engine). In running without the valve cover on, It did not seem to be the source of the noise, But maybe to source of the sandy residue I'm seeing?

Attached Thumbnails

 

The metallic tap is likely due to a an excessive clearance of........maybe .050". Do you think you're able to "see" such an issue? I'm sure I can't.

Can you provide any scenario where such wear would result in a metallic tap that is exactly one-half engine speed?

Can you provide any scenario where the metallic particles generated by such wear would migrate up and over the top of the block to get inside the valve cover?

That's a proper conclusion.

True But I did a full valve adjustment, and it's correct now. before i did the adjustment, all of them where really tight. REALLY tight. Like it was the first time it had been done tight. The adjustment to within spec made no difference on the noise. I did the readjustment with the engine cold. (sitting overnight)

Unfortunately no. please keep in mind that this is totally new to me.

Again no. I'm learning slowly, but is only the second time I've ever even seen the inside of the valve cover, I've did a valve adjustment on my cd, but have a feeling I should go back and do it again just to make sure.

sweet. so I can at least rule that out.

The sound seems to be coming from the area I circled in that diagram. at least, from the outside with the engine running that's the loudest point. Which is why I looked at it in the first place.

It's absolutely possible for the tensioning rail or the tensioner (the items which you circled) to wear significantly. However, I cannot grasp any scenario where this wear would result in a noise that is once per every two revolutions.

Maybe others have an opinion.

What if I loosen up the valve a little more on the first cylinder? Would that give it a greater clearance? And maybe help? I'll go pull the cover off again and get some good pictures of everything in there.

Yes, it would give greater clearance.

Now you'll have two different noises at one-half engine speed....................


I thought we understood that the noise is caused by a clearance on the order of .050" somewhere? We also determined that one cannot visually see .050" in almost all cases unless one knows exactly where to look.

We all are quite clear about what is under the valve cover and the results of a photo from two feet won't enhance that knowledge.

Well, here are some pics anyway.....

Lobes all look fine... But we have established that.



Notice the wear?



Here you can see the misalignment I was talking of



Here's the crap in the valve cover...



And last but not least the crap from the cover on my finger...

Attached Thumbnails