87 300d 197k
I've owned this car for about 20,000 miles and it has always made a tapping noise if started cold and then idled. It also makes the noise (with greater frequency--more taps per revolution) when started cold, shut down, and started cold a few minutes later.
It goes away if I drive hard on the highway for a good 20 minutes. Even better is climbing a steep hill at low speed--all the noise is gone and it purrs beautifully.
I've talked to some people and some think it's a lifter, but some think it's an injector. Others have no idea but have suggested synthetic oil. The crankcase is full of Mobil 1 10w30 presently. I eased the engine onto synthetic with a 3/8 portion of synthetic, then 1/2, then 5/8, and full synthetic is planned for the next oil change (in a week or so). I started phasing in
the Mobil 1 at 191k.
If it is a lifter, I have a can of B-12 Chem Tool by Berryman Products. It has toluene and benzene and some pretty harsh chemicals in it, so I'd like to know if it is likely to do harm if I mix a little in before I suck the oil out with my Topsider. (It says to pull the oil pan but logistics dictate that I cannot do that.)
When the lifters/injectors/whatever have been ticking and clacking for a long time during a drive in town, I get a large amount of smoke if I floor the accelerator. The smoke eventually clears and I get a little more spunk from the engine than before.
I have recorded the sounds in two MP3 files available at
I look forward to hearing from fellow diesel owners!
Justin Dobbs (email@example.com)