m engine

I am considering overhauling my old m that has been sitting for a few years, it ran when parked but always had a little oil in the water,now when I pulled oil drain plug all that came out was pure anti freeze,should I be worried about a cracked block or just bad sleeves or maybe cracked head.thank you for your input

An M has dry sleeves. At least they are supposed to be dry.

You could be getting antifreeze from the head or just a bad head gskt. or it could vary well be the block is cracked behind a sleeve ??? don't know for sure and the only real way to find out is , yep yo guessed it to take her all the way down and look as you go . If you know how to read a head gskt for signs of leakage yo may find that it was just the head gskt. But for me i am never that lucky . As for the head yep they do crack and this may be the problem. Here again you may be able to see a crack after ya get here cleaned up and look then you may have to have it tested by someone that knows how to do it and many times today they do a half arres job of it . as i have seen one tomany times where they will say yep it is good no leaks COLD but put a little heat to it she will look like old faithful as a dry air pressure test sometimes will not show but do a hyd. test with 40 psi air and warm it up whole different ball game . If it is indeed cracked behind the sleeve don't panic a good machine shop can bore that hole out and press in a repair sleeve and rebore it to take a new sleeve and it is FIXED . It was just the block stress relieving it's self. The MD's -450D's were good for this .

I like to pull the oil pan first ,fill with water and look up with a light sometimes you can see where the leak is comeing from.