diesel newbie needing advice
 

hello gentlemen,

i recently purchased a 1985 300d turbo for $500 with 267k.
she ran and looked like a $500 mercedes and had a #1 injector line leaking like a fountain. surprisingly it went down the road well and i felt sorry for it.
having no previous service history, i changed all the fluids, filters, the leaking injector line, and adjusted the valves which were all tight. the engine seemed to run much better but i knew that it still wasn't right.
using a long screwdriver i listened to each cylinder and #1 was nailing. at this point i felt it was time to check the injectors and compression. using the bosch tester, all injectors passed spray,
leak, and pressure test. i now had a sinking feeling.
much to my dismay, the old motometer compession tester confirmed my worst thoughts. the #1 cylinder was 100psi and the rest varied between 240psi-300psi, hot of course.
since i am not familiar with this particular engine, are there any other thoughts? would i be wasting my time to pull the head for inspection? can the oil pan be removed with the engine in the car for a quick ring job and a valve lap?
any help or advice greatly appreciated! btw, this is a great site and keep up the good work.
regards,
rob

Yes, it is true: "Nothing is more expensive than a cheap Mercedes". You don't have much money in the car. How about pulling the motor and trans and finding a good used motor? You can't do the piston without pulling the motor out anyway. Used engines are available. I've even seen a couple on ebay. Might get you going for a couple thousand.

Well, if you don't mind sinking a few grand into it, take it to a mercedes shop, have them do everything that needs done to it. It will come back running like new. That's what I did.

After you are finished "pulling the Motor" try removing the ENGINE because that is where your problems are.

Actually, You might try a wet and dry compression test to determine if the low compression is caused by bad rings or valves. If it is the valves you can take the head to a shop and get the valves rebuilt or replaced, the seats reground and possibly the guides replaced.

I think the #1 cylinder piston can be removed by just removing the lower oil pan which is easy. So you could just replace the rings in #1 cylinder if they are bad. But, do the valve job anyway since you have the head off. Its not too espensive. Don't forget to put in new valve seals.

P E H

My advise would be just drive it until it drops. You said it drove good, but you hear some nailing. So, just keep driving it, I bet you will get another 50K out o it, if not more.

The number one hole commonly fails more often. It is actually a different size on some engines.(I said engine instead of motor just for you P.E.):)

P.E. is right on top of things because I forgot that you could pull the number one piston/rod by pulling the lower oil pan.

If it were mine, I think I would be tempted to pull the head and the piston for a little exploratory surgery. If the cylinder is good, not scored or excessively tapered, a piston might very well get the job done. Since the other holes seem to be in good shape, this might work out pretty good.

I suspect the piston because I had one noisy before my 240D engine came apart at 380,000. Turned out the hole that was rattling had a piston with ring land faliure that was just about ready to seriously let go.

If you have a good, reasonable machine shop to do the head, this could be a cost effective repair if you can do the work yourself.

Best of luck,