Hi all,

I'm new to this forum. Great information on here!

I probably know the answer before I even ask the question (do an engine swap), but I thought I'd ask anyway. I have a 1984 300SD with the original engine, which has never been overhauled. Highway car all its life, and still looks awesome. I had a valve job done (broken valve guide was causing all kinds of problems) at 703K miles. Ran great for about 20K, and it started acting up again. Right now, I have a really rough (and blue-smokey) idle. Once you get it running down the road, it still runs like a champ. But at idle, it's smoking, running rough, just really carrying on. The exhaust smells to me like raw fuel. I have a perfect spare engine. Today, I switched injectors. No noticeable difference (I was hoping it was just a sticky injector).

The main thing that concerned me when I changed out the injectors was that there was engine oil on the end of both the front two injectors. A little bit on the rear injector, and the other two, 3 & 4, were pretty much dry. Would that be a sign of rings letting oil past? Like I said, I'm no mechanic. Just an ignorant guy asking more knowledgeable folks!

I've been driving these old MB diesels for many years, but I'm no mechanic. I can do parts swaps, etc., not a complete idiot, but not an expert either. Just wondering if anyone has any ideas on this. I want to keep this old engine alive as long as possible. That was the goal when I bought it. Is it time to give up the ghost and accept the fact that she needs an overhaul (or engine swap in my case), or do you think there's a chance to keep her going?

Any input will be greatly appreciated. Thank you!