Tapping noise - intermittent and repeating ... - PeachParts Mercedes-Benz Forum

stephenson · #1 05-07-2006, 06:10 PM

Coming back from a 2 hour drive today as was driving through my neighborhood at around 20 MPH noted a faint "tapping" noise. Got to house and let idle - tapping coming from injector side of engine most noticable around first third (#1 or 2 cylinder) of the head.

Strangely it taps consistently and faintly, but noticeably, for about 30 seconds then cleanly stops, then starts again for another 30 seconds ... follows engine speed but not noticable as the speed increases as the engine noise covers any potential noice ...

Was thinking lifter? But, why would it cycle ...

Anyone had this happen before?

Thanks!

stephenson · #2 05-07-2006, 07:40 PM

Waited a couple of hours .... started back up .... now can't hear anything - well, other than some mild hammering and beautiful diesel noise (not as sweet as my previous 5 cylinder, but nice nonetheless).

I changed the oil last weekend, but have put 250 miles on it since then with nada issues ...

Will be driving it for about 150 miles tomorrow ... any thoughts?

Thanks!

t walgamuth · #3 05-07-2006, 09:11 PM

the hydraulic valve adjusters are sensitive to oil type and viscosity.

what are you using?

tom w

stephenson · #4 05-08-2006, 01:52 PM

Mobil 1 15-50 ... same as for last 80K on this engine and several others before ... ran great this morning ... heard it when I stopped after 80 MPH run of 60 miles ... beginning to think is hammering from IP ...

Nothing else seems to be affected ... comes and goes ... randomly, but when it is there, like this morning, "ticked" in increasing volume, but still pretty quietly for 8 seconds, then off for 3-5 then 8 etc ... I listen a lot to my equipment and this is a new sound ... just don't know if it is important, yet?

Thanks!

ConnClark · #5 05-08-2006, 02:05 PM

The tapping is a gremlin trapped inside your valve cover. You better let it out.

Hatterasguy · #6 05-08-2006, 03:05 PM

Sounds like a lifter, no worries, change it if it bothers you.

They are not to hard to change, you need to remove the cam which is pretty easy. Cost about $25 each.

If you hadn't been running Mobil 1 my sudjestion would be to try Mobil 1 and see if it goes away. But since you already are there isn't much more you can do in that respect.

t walgamuth · #7 05-08-2006, 08:35 PM

i woud try one weight lighter oil. if it meets the recommendations.

tom w

Brian Carlton · #8 05-08-2006, 08:44 PM

It's definitely a lifter. And, they do cycle........somewhat randomly.

The SDL ('86) will get a spate of lifter noise for awhile and then nothing for several months. A very heavy and hot run for four hours on the highway will usually get one of them talking for a awhile. But, the next day, it's gone.

They have a mind of their own..........

stephenson · #9 05-09-2006, 06:31 PM

I drove the bejesus out of it yesterday - in town to 100 miles on the road at 75 plus ... roll back into the garage and let it idle - nada! While I like the nada better than the other options, it is a bit weird - and, if the lifters do this intermittently, it is great, again, to know a bunch of folks like yourselves that can share your experiences ... I will listen carefully and make determination if it recurs (and gets worse) about what to do ...

I had considered the oil viscocity issue, but am somewhat concerned about shifting to something thinner with 182K miles on it ... actually, now that I type this out, I am very pleased to even say that I have a 3.5L with 182K on it!

I've always wanted to tear into it somewhere and furthest I ever got was R&R of the intake system ...

Thanks, again!

Hatterasguy · #10 05-09-2006, 06:42 PM

You may want to consider switching to Delvac 1 5w40 next time around. It isn't too thin for these engines mine love it and I have 254k on mine. It is a long shot but it may help.

I just changed all my lifters over the winter because they were driving me nuts! One of the new ones is ticking.

I'm going to drive it for a bit and see if it goes away. Lucky for me the dealer threw in two new lifters for free!

stephenson · #11 05-09-2006, 06:49 PM

I used it for awhile, but once it got to $6 a quart, I bailed ... if I could find a reasonable price on it, I would for sure use it!

Thanks, again!