Yes, I see that the Technical Manual only covers the re-torque process. The information for the head installation torque procedure must be extracted from both the early and late BBBs. The head installation torque process for the 230SLs and 250SLs is describe in the early BBB (p. 00-0/26) foot note #1 and #2.
The Early BBB reads....
Foot note #1
"Before tightening cylinder head screws apply graphite oil (Auto Kollag) to the threads and to the contact surfaces of the cylinder head screws and the washers.
The instructions for the tightening sequence and for the tightening stages of the cylinder head screws should be strictly adhered to (see Page 00-0/21)" I suggest that there is a factory typo error here (see Page 00-0/21 ) should actually read (see Page 00-0/27)
Foot note #2
"After installing the cylinder head, warm up the engine under slight load until the cooling water temperature reaches 80 C. Run the engine for approx. 5 minutes at this cooling water temperature and then tighten tighten the cylinder head screws with the engine warm according to the values listed above." (these values for the head scews for 230SL engine and 250-SL engine are listed as 8 mpk cold and 9 mpk hot on page 00-0/25 of the early BBB).
(1 mpk= 7.22 foot lbs of torque)
"Carry out second retightening after another 300-1000km."
"Caution: When retightening the cylinder head screws there is a danger of omitting the necessary retightening because the unscrewing torque is usually higher than the prescribed tightening torque and it thus must be possible for the torque value in first tightening phase to be above the nominal tightening torque.
In order to insure that the cylinder head gasket is really fitted with the prescribed screw tightening torque the retightening of the cylinder head screws should be carried out as follows:
Each screw should be slightly loosened in the sequence laid down in the screw schedule and should then be tightened to the prescribed tightening torque." (one at a time!) "Under no circumstances should all screws be unscrewed in one operation and then tightened. "
For the 230SL (M127 engines) and the 250SLs (M129 engines) page 00-0/27 of the early BBB, breaks down the torque process into four stages .......4 mkp cold, then 6 mkp cold, then 8 mpk cold the last check pass is 9 mpk ( warm engine 80 C)
Now if you have a 280SL(M130 engine) page 00-0/16 of the later BBB lists the torque value at 10 mkp cold and 11 mkp hot. Foot notes #1 and #2 on page 00-0/17 of the late BBB gives basically the same information as the above footnotes. The tightening sequence for the 280-SL (M130 engines) is on page 00-0/18 of the late BBB and is the same as the earlier engines (above). In addition page 00-01/8 of the late BBB breaks down the torque process into four stages for the 280 SL (M130 engine).......4 mkp cold, then 7 mkp cold, then 10 mpk cold the last check pass is 11 mpk ( warm engine 80 C). "Oil" in the late BBB is prescribed as the head screw lubricant in place of "graqhite oil" as in the early BBB. I suspect that it is your choice here. I use graphite oil.
Lastly, in regards to the small 8mm allen screws at the front of the head both BBBs state "The other screws "a" with the M 8 thread should be tightened by means of a hand wrench." in other words "by feel".........
As we have learned, it is necessary to sift through a lot of information in various factory shop manuals to extract some basiic information.
One last note, if you have the cylinder head off, clean the head bolt holes and threads. Use compressed air to blow debris out, run the correct metric tap with solvent or oil to clean all threads and use compressed air to clear once again. Wipe block and head surfaces clean and dry with alcohol or solvent before installing new gasket and head. Lube bolt threads and under bolt head and torque as described.
Happy Motoring
Joe Alexander
Blacklick Ohio
