buying used M30 3.4 liter engine

[Ilia Zharkov <zharkov@xxxxxxxxxxxxx>]

Hi guys,

Here is the story. My engine leaks oil into coolant and it is doing so since I 
bought the car.  Obviously, the damned guy who sold it to me concealed this 
rather unpleasant feature from me.  

Couple of years ago I changed the head gasket and while doing so noticed two 
tiny hairline cracks between the bolt holes and coolant passages in the block.  
Things improved with the new gasket a little bit, though still overheating 
in summer traffic with increasing amount of that milky stuff in coolant.  But
now it starts leaking a lot again, even if not terribly overheating. So I am
thinking of replacing the motor. Or the block only since the head looked fine when I
inspected it two years ago. 

I don't want to by a new (rebuilt) one since the car is not in perfect shape
and it does not seem worth investing $3000 in it. Rather I am thinking of
getting some junk motor. There are 4 or 5 listed in car-parts.com in the
Raleigh-Durham area for $650-$900.

I need an advice what kind of things I should look for in a junk engine.  Are 
there some simple tests I could do on the spot to tell a good motor from total 
junk. 

Any advice (including not to buy a junk motor) will be greatly appreciated.
Thanks,

Ilia Zharkov.
'87 535is 145k, heart contaminated

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