Because if you remove all the rockers there is no tendency for the cam to turn the engine because some rocker is pushing on a cam lobe. Take all the rockers off and the engine moves easily and stays put.

It was on a 116 engine. But I also own an M103 but I have not yet changed the seals. But it is in the job jar. What type of spring compressor are you using? I had to buy a special for the 116. Maybe I could borrow yours ??

__________________
I got too many cars!! Insurance eats me alive. Dave

78 Corvette Stingray - 3k
82 242 Turbo Volvo - Manual - 270k
86 300e 5 speed manual - 210k
87 420sel - 240k
89 560sl - 78k
91 420sel - 205k
91 560sel - 85k
94 GMC Suburban - 90k
97 Harley Davidson Heritage Softail - 25k
00 GMC Silverado 1 ton 30k

I had the head off my M117 so I used a c-clamp compressor. I have a generic hooks-the-cam compressor. I've yet to see if it works on the M103.

Sixto
91 300SE
81 300SD
78 450SEL (sold)

Aren't the rockers matched?

Sure they are. You must be careful to get them back on the way they came off.

__________________
I got too many cars!! Insurance eats me alive. Dave

78 Corvette Stingray - 3k
82 242 Turbo Volvo - Manual - 270k
86 300e 5 speed manual - 210k
87 420sel - 240k
89 560sl - 78k
91 420sel - 205k
91 560sel - 85k
94 GMC Suburban - 90k
97 Harley Davidson Heritage Softail - 25k
00 GMC Silverado 1 ton 30k