lol, i told my wife the title to this thread and you know her response,ok course she suggested that i should write about hard heads.
ok forum, this one should last a while.
i have been trying to determine why so much trouble with heads on the mercedes engines.
i got a couple heads from locals that were about to be scrap and had a couple of my own to experiment with.
i tested the free heads and found that the aluminum had softened (down to average of 20 on the rockwell b scale as compared to high 80's as per mercedes specs)
the soft heads had all kinds of problems,stripped threads at the rocker arm hold down bolts,and on one that i removed from a running engine(91 300e 3 liter) the head bolts were loose to the point that there was no snap at all when removing. i even re tightened to specs and removed again and got that soft feel as the bolt released.
i dont see how anyone could afford a new head for one of these engines ,so i am experimenting with the process of re-hardning the soft heads and have completed one was 20 rockwell b and now is 85.
i am having to borrow a rockwell tester,so if anyone knows a source for a used one(i can calibrate it)let me know.
also anyone who has any aluminum heads that i could get i would pay the frt and a reasonable value.
would be interesting to hear of some of the forums special projects.
larry perkins lou ky 15027276903