Loud knocking and LOTS of Blow-By: 300SD

[cousindave76]

I have an 83' 300sd 198k. My engine has always run very smooth with all the right sounds. I just starting hearing a very loud knocking sound. I would describe the sound as being a bad valve. Because this is a 617 Diesel, I realize that may not be the case. The other new symptom that started with this sound is serious blow-by. I have checked my blow-by in the past and found that I had very little. Now that I heard this sound I decided to check it again. I found that it has a LOT of blow-by now. This scares me

I would like to know the proper steps for diagnosing this problem???

I have new glow plugs and my injectors are new as of one year ago. I have not checked IP timming. I have had a new timming chain installed and valve adjustment done by an MB shop about 6 months ago.

I would guess a cracked pre-chamber or, bad injector to be causing this knocking sound but, this new blow-by situation leads me to believe it may be something more serious.

Has anyone had a similar experience and found it to be something other than a bad valve?

Your advise please