Afroney

Im starting to get lifter chatter in my 86 4000csq. Its pretty loud now, only at idle. The sound is exactly like the time when my Benz 300 Diesel blew all the oil out and the engine siezed. Hope thats whats not happening to mine. Any suggestions? The oil was changed a few weeks ago, with Mobil 1 synthetic, (Ive been using that same brand of oil for the past 3 years).

Whitjr

Had taken a 450 mile trip in my 4000s, and returned with the same clatter you are describing, [this is around Thanksgiving] and was losing oil, had erratic reads from the BAR gauge, and was really worried about it. Here's what I did that reduced my worries, but you may think this is crazy....

1] found my leak, and corrected. I was losing oil from around the seal where the oil filter assembly mates to the bloc.
2] replaced two quarts of oil with Marvel Mystry Oil, and ran it for two weeks that way. worried about it the whole time, however kept the ususal driving speeds and communte happin', no variances. Mine is a daily driver, 82 miles round trip. Gradualy I noticed that the valve clatter was diminishing.
3] Did the usual oil change on Saturday w/ 20w50, and Wollahhhhh! No more valve clatter, no more erratic BAR reads, and everything seems fine.

I'm guessing that my engine [maybe yours as well] got some of thise small channels clogged with s**t from all the years these cars have been on the road, and the MM oil cleaned it out very well. Don't know it this will work for you, but this certainly assisted me with mine.

Good luck with yours!

Cdn Blue Coupe

Check your oil level!

CGTBrad

The correct way to diagnose worn out lifers is:
(this is from memory)
Let the car idle. After the cooling fan cycles once, run the engine at 2500 rpms for 2 minutes. If they are still ticking you've got some worn lifters. Like Whityjr said, MM Oil seems to help by cleaning out sludge and crap. I used a quart every oil change and it seems to help keep them quiet.

CoffeeMan

here's the deal: my 87 4kq has some lifter chatter... it's getting a little worse. I went to an audi shop closeby and talked to them about it and they suggested a lifter treatment that you add on top of a fresh oil change. unfortunately, you can't buy this stuff... if you could it would be 400 bucks a gallon. however you only need 40 bucks worth. so just take your car to an audi shop and have them change your oil and put in some lifter treatment, make sure it stays in for 3,000 miles and they told me that would take care of it since it's not too bad yet. I'm takin it in tomorrow... I'll let you know