Update: Head is at Metric Diesels, who was also willing to hot-tank the intake (saving me approximately 8.7 cans of carb/choke cleaner and a killer headache).

Meanwhile, I'm cleaning up the other parts after hours at work. It's nice having access to a sandblaster.

http://lh4.ggpht.com/_o_3o6xcLap8/TN...0/IMG_0899.JPG

I still need to weld some repairs over the ripped out holes in the turbo heat shield.

http://lh5.ggpht.com/_o_3o6xcLap8/TN...0/IMG_0898.JPG

Yup, Brian's Right--It wont fall off or jump a tooth on the IP drive as there is a bolt guarding against this in the outside of the timing-housing--Its that bolt-head about halfway round the curved casting round the IP sprocket, appearing to be holding nothing!--If you remove it, you'll see it just goes into the side and has a thread-free section a set length....:)

The chain Should Not (But concievably could--if the guide is damaged) slip off the crank either, as the chain guide at the right-hand-side holds the chain very close to the sprocket, so it cant come disengaged...:)

So yes, its quite safe to just let the chain fall in there, Done it myself, fished it out with magnet and just got on with re-assembly....

You CAN turn the engine but you Must keep light tension on the chain while turning engine, to prevent it bunching up at the bottom....

--And Only Turn It Clockwise while looking from Front....:D

Remember you'll HAVE to turn the Crank Two Revolutions to end up where you are for timing....

Ive done all this myself, so I Know its all quite safe and easy....:D

Bad news - engine shop says the head is not rebuildable. Cracks throughout, needs new valves.. :(

Looks like there'll be a trip to a P&P in your future. Interesting that your car seemed to be running pretty well despite the wear.

Many people on this forum don't like to see me post here any more, so I apologize if I draw all sorts of hate mail to your thread.

I did not read the entire thread, only up to this point. What I've read to this point is all the information I need to post my thoughts.

You said that it runs reasonably well and it doesn't use an excessive amount of oil. The good news about a diesel is that if it's hittin' on all cylinders, has reasonable oil pressure and is not using so much oil that you can't carry enough with you to get where you're going, you can just keep on driving it. Unlike a gas engine that will start fouling spark plugs and other ills when they get worn, you can just keep chugging down the road in a diesel.

Given the value of the car as compared to the cost of an engine overhaul, just keep maintaining it normally, drive it and enjoy it. FORGET the numbers.

Hope this helps.

Hmm....

Thats a pity!

--Darn shame you're the other side of the world, I have a couple of spare complete engines with good heads....

There's bound to be someone nearer to you who has a good servicable head they can contribute to your cause for some beer-money....:)

The 617 isnt known for cracking heads just old-age faults like wear on the guides/valves, but these are reasonably easily changed.

Personally Ive not ever seen a cracked 617 head, yours must have been severely boiled up sometime in its past life....:(

Thanks to all who shared insight on the dreaded thought of dropping the timing chain and 'losing it all' as it were.

I'd still be downright paranoid of the IP sprocket turning slightly as the chain dropped - and then having to face the murky depths of trying to dial the IP sprocket back to where things should be.

It's a shame that there's not an easy way (that I'm aware of), to get one's hands on a shop manual to properly see how the 617 was put together, how it should be assembled, and seeing the potential traps that lie in waiting for the semi-experienced individual. I've experienced the fun of torque-to-yield fasteners with the new GM V8 motors; I'm not sure that applies to anything on the 617, but I do vaguely recall cyl. head torque specs that seemed to state a specific torque value, then an additional turn of 1/4.

What I do love about the 617 is that it does seem set up for maintenance and for serviceability. It's annoying that several areas of normal maintenance are shrouded in grey. I've steadfastly held off on pulling the head on my 82 300SD due to the probability of mucking up IP timing, and then secondly, not being able to find the proper head bolt torquing sequence or values.

While I've seen posts on manuals on CD listed here, I'm one of the weird who really just wants to hold the actual, published manual in his hands.

Many thanks for the existence of this forum, and for the help I've received firsthand from all the posts gathered here. You've helped keep my car on the road for the past three years and for over 100,000 miles. I hope to log many more. Sure, I could get a beater Honda or similar; nothing but absolutely nothing says more than when you first sit in the driver's seat. The Mercedes just says, 'If you take care of me, there's no reason we shouldn't keep on going'.

I have a benz manual, on CD, purchased from the dealer almost 10 years ago. It's largely a collection of PDFs that appear to be copied out of a paper manual. While it's useful, I still find myself referring to the W123 Haynes manual for stuff.

And speaking of stuff from almost a decade or so back.. Hi Larry! I lurked for a while before I joined, but tips from guys like Larry helped me keep the benz running while I was a poor and largely inept college student.


But back to the benz... I bought this for a core on ebay
http://lh6.ggpht.com/_o_3o6xcLap8/TN...0/benzhead.JPG

Mic'd the cylinders - Largest diameter measurement was 90.98, wear limit is .10. Eccentricity was ok, off by no more than .036
(all units in millimeters)

How do I find the original diameter of the bores? The manual refers to bore/piston sets by three groups, and gives min/max diameter for each.

Yes, the head bolts are torque to yield.

I DO understand your desire for a paper manual. If you haven't gotten one yet, you will probably be surprised at how well the Haynes 123 manual covers these engines, and many other portions of the car.

It's been a while since I looked at this portion of the Haynes manual. It doesn't have bore diameters? It seems like I remember it even having the unique size of number one.

Wow. With that in mind, I'm assuming then that the head bolts are *not* reusable? Bolt stretch usually results in a weakened fastener; if I'm remembering Tex Smith's advice on fasteners correctly, used torque-to-yield bolts should be thrown away.

Thanks for the heads up on the 123 Haynes!

Thanks Kerry! I'll check it out!

What does torque to yield mean? One time use?

It means that when the bolts are torqued down, the force is enough to cause a permanent stretch in the bolt.

It can only be done once in a bolt's lifetime. Say a bolt takes 5000 lbs before yielding (straight pull force, not torque, that is). If you torque it until it's applying 5000 lbs of clamping force on the head, it's right at yield, and it's stretched a small amount. You could untorque it at that point, and it would go back to its original size.

If you turned it another quarter turn from that yield point, some of the stretch becomes permanent. Untorque it, remove it, it's going to be a few thousands of an inch longer. But if you re-install it, it's going to take more than 5000 lbs of force to make it yield again.