Troubleshooting my engine knock (long-ish) 1982 300D - Page 11 - PeachParts Mercedes-Benz Forum

layback40 · #**151** 02-22-2010, 07:17 PM

Does your neighbor have any experience with Benz diesels?
Good luck !!

konstan · #**152** 02-22-2010, 09:22 PM

Most of his experience is with industrial equipment and with semi tractors... no, probably not too many benzes...

Everyone says its so easy to pull the om616/om617 engines out... I will soon find out for myself!

jt20 · #**153** 02-23-2010, 02:33 AM

Konstan,

I have yet to see the mileage for this engine, what is it?

We are seriously doubting the timing device as the source of the 'knock', correct?

From my limited experience, despite what the commoners may say, these engines require a complete inspection by third / fourth ownership or 200K miles - whichever comes first. By that time they need a head rebuild at least and most likely some minor bottom end work at most. (wrist pins, chain, smaller items, guides)

konstan · #**154** 02-23-2010, 01:26 PM

It has about 215k miles on it but the odo was broken (its one of the first things that i repaired), so true mileage is really unknown. It could be 300+k, who knows.

I doubt that the timing device is the source of knock because mainly it would knock if the vac pump was still attached. In my case it knocked with the pump off, too. I am still going to fix the play, lest another pump gets destroyed, but it just could not possibly cause such a consistent knocking sound.

Don't forget the metal balls in the oil pan that I found. They indicate a previously failed vacuum pump. They could have done some lower end damage - broken pinson skirt, wrist pin, whatever.

Combined with the fact that I have only 1 bar of pressure at idle, hot or cold, I think points at low end issue as well. Even though the noise sounds 'top end'. That oil pressure, at low rpm, is finding an exit somewhere.

Pulling the motor seems easy to do, in fact I already have most of the stuff disconnected. And it would make it so much easier to access everything on it. I will take the lower pan off to check the bearings, wrist pins and all that stuff. Then the head if I need to.

In my opinion its the only way to be able to tell if it's toast, or to make sure that the next time I fire it up it does not knock anymore. With the cost of oil, coolant, tranny fluid and stuff, I dont want to keep filling it up and draining it, that gets expensive too