a few more questios re: head removal
 

In the process of getting ready for a long weekend of car repairs (head replacement), I have a few more questions:

1) I got new head bolts from Fastlane. They do not come with washers. Should I use the old ones? Should I use off the shelf metric washers at Auto Zone? Or should I buy new OE washers?

2) I see in the MBZ repair manual a diagram of the timing chain. There is a bolt called the "chain lock" that appears to lock the chain onto the drivers side of the injection timing gear. Should I screw in this bolt when I want to secure the chain and prevent from skipping a tooth? I will use PSFred's suggestion of inserting a flat piece of metal stock (brazing rod or similar) through both sides of the chain when I lift up the head....looks from the diagram that I should pull the driver's side of the chain toward the passenger side to prevent from skipping a tooth on timing gear...any thoughts? (I really want to make sure I dont screw this up!)

3) Fast lane had all of the head bolts except for two of the short ones at the very front around the timing chain housing....I assume I can re-use the old ones since I don't think these are critical "stretch bolts" as on remaining area of the head...is that true, or should I get the two new ones so I have a complete new set?

4) Why does a "head gasket set" contain only the head gasket and exhaust manifold gasket, and not the intake manifold gasket which must be bought separately???

Thanks again for all the help,

Mark

a) You can use the same washers on the head bolts if they look ok.
b) You can't go wrong keeping tension on the timing chain - I pull mine over toward the pass. side.
c) Reusing the small bolts up at the front of the cam cover is fine.
d) Look at the way the intake/exhaust attach. It is the same gasket.

If you use other washers I suggest using nothing less than grade 8 .....

Do NOT use off-the-shelf washers, no matter what grade. The original washers are hardened and (most likely) parallel ground to ensure full & even contact with the surfaces for proper load distribution. I reused mine.

RTH

RTH, Don't you think grade 8 pretty much constitutes hardened washers ? LOL Greg

The head bolt washers are also much thicker than off-the-shelf washers. Re-use the old ones.

Re: LOL - If you really want to know…
 

Grade 8 hardware will be sized per SAE specifications; inappropriate for the job at hand. In addition to the thickness noted above by Mplafleur, there is the factor of *how* hard the factory washers are. If memory serves me correctly, grade 8 hardware is fabricated from medium carbon alloy steel, and is rated at approximately 33-36 on the Rockwell scale. Grade 8 is roughly equivalent to a metric grade of 10.9. Metric grade 12.9 is significantly harder.

Why does all this matter? The force under the head of a bolt or nut can exceed, at high preloads, the compressive yield strength of the clamped material (e.g., the washer). If this occurs, excessive embedding and deformation can result in bolt preload loss. Not a good thing, unless you want your fastened joints to have clamping pressures below spec.

RTH