did you helicoil the bolt holes in the block before you replaced the heads? the block is aluminum and the head bolts are steel.it is not a matter of if the aluminum threads will break BUT WHEN.i have seen this job done several times without helicoiling and a short time later the threads let go on one or more bolts and coolant leaks.i would remove the valve covers and check all the bolts to see if this has happened to you.

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David S Poole
European Performance
Dallas, TX
4696880422

"Fortune favors the prepared mind"
1987 Mercedes Benz 420SEL
1988 Mercedes Benz 300TE (With new evaporator)
2000 Mercedes Benz C280
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