E300D tapping sound
 

Hi,

I have a 1996 E300D with approx. 130k miles on it. I just recently started hearing a tapping noise. Using a auto stethoscope I have tried to pinpoint the noise...it seems loudest when I put it on top of the black plastic cover that sits overtop the center of the engine.....the part nearest the firewall.

Any ideas or suggestions on what this might be ? Perhaps a worn rocker or sticking lifter ? Is there a regular adjustment required to the valve train ?

Thanks in advance for your help !

Brian

Could be a lifter, but on 606's thats kind of rare. What kind of oil are you running?

Losen the injector lines one by one and see if it goes away.

thanks for your reply ! I am running rotella 15w40. I am curious, what would losening the injector lines tell me ?

Thanks !

It could be the puck in the vent line. Are you sure that this is a new noise?

the what-now?

Have you listened to each of the metal fuel lines...might be an easier first step before cracking those lines to rule out a slightly bad inj.

I don't know the real name for it, but it sure looks like a puck. It's under the plastic cover.

It could be a slight nailing, by losening the injector lines you deactivate that injector so you can narrow it down.

The lifters on 606's don't seem to act up at all, not like the older 603.

CCV?

I will try the stethoscope on the injector lines first to see if the sound is coming from there. Next I will try loosening the injector lines....question, where do I loosen them ? Won't this cause fuel to spray all over the place ?

Thanks for all the advice !

Brian

You are just cracking them open a turn or two. They will leak only; not spray.

Is prob easiest at the IP.

Its an oil separator held down by 2 bolts, unlikely its making the noise.

Remove the black plastic cover and go from there. Whichever cylinder is knocking (if it is a cylinder) will be apparent just by resting a screwdriver on the injector line and putting your ear to the thick end.

Hi,

I have now removed the crossover & black plastic cover. Used my stethoscope to listen to each of the injectors....the one closest to the firewall is quite noisy, the next one in is a bit noisy, then the rest seem "normal"...any idea on a diagnosis ? One more thing, it appears as though the black plastic cover is adding to the noise as I cannot hear the noise very well after removing it.

Any ideas ? Do I have a bad injector ? Where should I go from here ?

Thanks in advance !

Brian

I believe I have at least 1 bad injector....I will remove them and take them to a local injection shop for testing/rebuilding....(any recomendations on a shop would be appreciated...I live in Raliegh NC). Thanks !

Also, I am wondering if someone can recommend where I can get one of those injector removal tools for < $60. (606-0009)

Thanks in advance,

Brian

FWIW my '98 has an intermittent "rythmic ticking" sound under partial load. I started noticing it about 18 months ago and it comes and goes. Almost sounds like pinging in a gasser but much more regular in frequency and varies with engine RPMs so I suspect it could be an injector too or a lifter but like others have said that is unusual for these engines.

Sometimes more noticeable sometimes very light, then not at all. The engine otherwise runs great, gets great mileage and has no other issues so I have not pursued it but have spoken with at least two others who also own 606's with the same symptoms. I looked into rebuilt injectors but at nearly $100 a pop it seemed like spending $600 to clear up what is only a minor annoyance was a bit much, even for me so I live with it. Like I said, it doesn't do it all the time and has been doing it for quite a while and has not gotten any worse over that time either.