The AERA rebuilt-engine break-in procedure can be found here. It includes information on oil designations. It isn't specific to Mercedes diesels, but has enough explainatory information to make an informed decision.

I've worked on a few engines that had not had their headbolts retorqued. That is an aspect that hasn't been mentioned in this discussion, but is critical for most engines after running for a few hours.

Cheers,
JohnO

quote:

Originally posted by johno:

I've worked on a few engines that had not had their headbolts retorqued. That is an aspect that hasn't been mentioned in this discussion, but is critical for most engines after running for a few hours.

Not necessarily these days.
Monotorque gaskets have been around a long time now and as their name indicates, You do them up once and that's it.
I don't know if they do them for benz diesels but there are a lot of engines commonly in use here they are available for.

I've replaced a few mono-torque head gaskets on older engines, both my own and customer's. I've also replaced quite a few blown headgaskets that were supposed to be retorqued, but weren't due to lazyness and wishful thinking. They left me with the impression that they may work ok on modern car engines, but may not work with older engines. The easy way to tell is to recheck the torque after a while - if the head bolts have loosened, then they need retorqued. If they are still at spec, then they don't. Why wait until a head gasket fails? It's easy enough to check the torque of at least one or two headbolts on any engine. Many engines require removal of the cam or other complication to reach all of the headbolts, but that shouldn't prevent you from checking the torque on headbolts that aren't blocked by the cam. If you discover that the headbolt is dramatically lower than spec torque, then it's worth the additional effort to gain access to them all.

hheynow - you didn't mention how old your 300D is, nor if the head gasket was the kind that is advertised as not needing to be retorqued. Do you know if it is? Is this too far off-topic? Retorquing headbolts isn't related to WVO use, but rather to care of rebuilt engines.

A side comment - My Mazda diesel headbolts had never been retorqued since leaving the factory. The engine ran just fine at over 200,000 miles. I checked the torque and it was only a little more than 50% of spec. I retorqued the headbolts and readjusted the valves. Nothing at all seemed to have changed, but the mazdadiesel discussion group believes this helps bump up compression a little. They might be right.

Cheers,
JohnO

quote:

Originally posted by johno:
A side comment - My Mazda diesel headbolts had never been retorqued since leaving the factory. The engine ran just fine at over 200,000 miles. I checked the torque and it was only a little more than 50% of spec. I retorqued the headbolts and readjusted the valves.

Seems Risky. Unless it was leaking, I would have let it be. What was your method? Remove bolt, clean/oil/retorque? (One by one)?

Nope, didn't remove the bolts (different engines have different rules) - this is from the shop manual - Back the bolt off 1/4 turn, then torque to spec in one smooth motion. Mazda 2200 diesel engines don't use "stretch" bolts like VW and some others. Anyone know what Mercedes use?

The Mazda is a pushrod engine, so compressing the head gasket decreases valve clearance. An overhead cam engine (e.g. Mercedes) won't have that problem.

Cheers,
JohnO

quote:

When can I safely use WVO in a rebuilt engine?

1500 miles was my rule of thumb and it's worked for 4 cyl. 5 a little longer maybe 2k max though and the rings should be seated.

Shame only Elsbett seems to have a handle on Diesel's VO sealing rings. Perhaps a wider groove and a fatter ring would seat more properly in VO. But in Lyle Cummin's book Diesel's Engine they talk a lot about the failure of rings in the beginning of Rudy Diesel's work. Though it seems by the time he was using VO he had a stable engine design so it makes me wonder how much work it would be to widen the grooves and fatten the rings - boring the chambers and grooving the pistons - I figure on a bored block it's only the bare min you have to keep to diesel.

Muzak I'm delighted you didn't read me the riot act for not getting a rebuilt 617.952 turbo.