97 E420 119 engine, 105k miles

problems:
1. at idle or moving, there is a tapping/ticking noise that seems to be coming from the lower half of the engine (rod bearing?). happens at P, N or D. The tapping gets quicker when I shift to N/D than at P, and the frequency increases as I give more gas. What is the problem and how urgently should this be addressed?

2. Car has a rough idle (at D or P, but worse in D). At P rpm is a bit higher but at D when the rpm is at about 700, the rpm would drop to 400-500 and then the car would get it up to 700 again.. this happens every 15-20 seconds. Car doesn't die though. No engine malfunction codes.

Are you the same guy that just had the timing chain replaced?

no.

Oh, ok , someone just called me with those similar problems on a 97 e-420 that just had a timing chain replaced and oiler tubes replaced due to engine ticking.
I was just wondering why those important details may have been left out.

Those 119 engines are notorious for having the plastic oiler tubes blow out inside the valve cover.

Question: Did the ticking noise and the rough idle happen simultaneously or one before the other?

You may or may not have more than one problem.

i've had the car for only 2 days so i can't say for sure when they started. possibly a while ago.

i was browsing another thread and found some interesting info. this gentleman had a very similar tapping noise, but check out his solution:

"
Turns out the problem was related to a Tech Service Bulletin P-B-07,00/21F-1260. They replaced front engine mounts with an updated mount. It completely quieted the engine ticking noise.

"

You could have collapsed motor mounts and they will make you feel every hickup in the engine that is normally insulated by the mounts taking all the shock.
You may also need a tune up as well.
How many miles are on it and do you have service records.

You can test the motor mounts by putting your hand on the front corner of the valve cover and push hard on the motor to see if it has any bounce to it,If it feel tight with no bounce, chances are the mounts are shot.
Also bad mounts may give you some engine rattle or rubbing ,humming noise on hard acceleration.
Also if you feel a jolt in your seat when you first start the car.

The ticking noise and rough idle could be a dead miss from a bad coil or spark plug or supressor end at the end of the coil that connects to the spark plug.

I can tell you how to diagnose that if you want to call me, or I can send you a pm.

The oiler tubes could be an issue still.

Thanks a lot for the suggestions. Are you coming up to Ann Arbor anytime soon?? haha


well, i really think the ticking and rough idle are NOT related, b/c the idle started last night after I pulled the air filter housing out and cleaned the air filter. (Also, the engine bay was filthy w/ lots of sand & leaves and i was cleaning these) This maybe why it's got a subtle rough idle now.

From my reading, the ticking noise is most likely caused in my 119 engine by bad oil guides and/or the engine mounts. Good thing is that neither are super critical for driving, so I'll leave these alone for now. I can always turn the radio up. The only thing is that the ticking seems to come from underneath, not from the valve covers..

The car is a 97 with 105k miles. 1 original owner. He had all maintenance receipts. Everything looks good, except the diff & ATF was never replaced. Also, there are multiple rust spots (Michigan) It looks like the car was not driven too much in the past year and was parked outside, so there are all kinds of debris & dead insects in the engine bay. I wouldn't be suprised if the engine mounts are bad.

Was your engine air filter really dirty?
Sometimes blowing the dirt out can create problems with the filter and could cause dirt particles to trash the mass airflow sensor after you put it all back together and run it.
Always just replace the filter instead of cleaning it, cause it can burn you.

Wanna have some fun?
Check your spark plugs and supressor ends out.
They, of course you probably know this,live under the black covers on the valve covers.
Be careful not to break anything.
Each coil has 2-5mm allen head bolts holding them down.
Pull the bolts, and pull the coils up and check out the supressor ends for cracks or white marks or water evidence.
I found mud in some before from flood cars that survived(barely).
Note: I always blow compressed air into the spark plug holes to blow out any debris before I remove the spark plugs, that way it won't fall into the hole when the plug is removed.
See how the plugs look.
Be gentle on flexing the wiring harness conneceted to the coils.
Carefule with the black purge valve line (driver side) hard plastic near front of drivers side valve cover.
Also the breather tube at rear of pass side valve cover may be like bubble gum,and or very hard and brittle.

ouch, that's exactly what i did. i ordered a new air filter but i cleaned the air filter yesterday b/c it was so dam# filthy.. perhaps i shouldn't have done that!! there was so much dust & crap in there, i was coughin for a good 10 mins in the garage.

i hope i didnt F-up the engine!! i won't run it til a new air filter arrives.. sigh