Quote:ound in the FSM (paper): section 400 page 7 "notes for cylinder heads and head gaskets" and in the electronic version: Mechanical Manual \ 01 Engine Removal and installation ... \ 400 Repair notes for cylinder heads and gaskets \

Chronology for re-designed head (primarily the OM603):

.. The earliest US-bound known 603 turbo head casting on the '86/'87 cars appears to be the 603 016 14 01. This number is cast into the head above the #2 injector. On later (angled-injection) versions the "603" is partially machined away.

"Production change for protection against cracks in water jacket"
"Since 10/87 the bolt flutes on the exhaust side have been reinforced and the recesses (hollows) between the coolant ducts on the outlet side filled to prevent cracks in the cylinder head water jacket."

-- This appears to be a #15 head (although a casting number change is not mentioned) which would pre-date the next change:

"The reinforcements at the valve tappet guides and exhaust passages have been reinforced. Modified cylinder heads can be recognized by the cast no. on the intake side, see table."

Engine ----- previous cast no. --- new cast no. --- Production Breakpoint
_______________________________________________________

602 ---------- 602 016 03 01 --- 602 016 07 01 --- 09/88

602 Turbo----- 602 016 06 01 --- 602 016 08 01 --- 07/89

603 ---------- 603 016 10 01 --- 603 016 16 01 --- 10/89

603 Turbo----- 603 016 15 01 --- 603 016 17 01 --- 07/89


-- This revision series was again succeeded by another change, the casting revision for which is again not mentioned:

"As of 12/88 the passage suports in the cylinder head water jacket were improved on the turbo-engines."


The gasket was revised also several times, the latest indicated was the 603.971 (3.5L in the W140) in 11/92 to improve the gas seal at contact point to timing case cover (section between cylinder #1 and the timing chain cavity).

There is also an "identificatoin strip" cast into the turbo heads to differentiate between them and the NA heads, which is at the top-left of the front of the head leading left of the existing boss extension (see page 400/4).

This is also the section (400) that discusses other head gasket changes, and pre-chamber changes.

Precombustion chambers and modifications to fit previous precombustion chambers to new heads is covered in 416 (paper) or 01 Engine removal and installation, ... \ Combustion Manual \ 416 Modifications to precombustion chambers.

This is a question asked almost weekly, hopefully this will provide a quick reference to this informaion.

Feel free to make this a sticky if the information is not already covered.