<BMW all> Subject: bad radiator or blown head gasket? cracked hea d?

["Sanders, Ron" <rls5@xxxxxxx>]

Aha, no good deed shall go unpunished!  Seriously, I think your problem may
be that there is air in the coolant system.  In your message, you don't
mention having bled the system repeatedly after replacing the radiator hose
and lost coolant.  Air becomes trapped in the upper sections of the cooling
system and causes all kinds of weird symptoms like temperature spikes,
surging coolant, and cold spots.  When I replaced the hoses on my Bimmers, I
had to purge the system 2-3 times before getting all of the air out.  Before
spending money, try the following.  I think all Bimmers built since the
early nineties have a dime sized screw near the upper radiator connection to
allow the system to be bled.   On earlier cars without this feature, you
will need to raise the front of the car (either with jack stands or a steep
driveway) so that the air bubbles will escape from the highest point, namely
the radiator cap opening.  Once the front end is raised so that the top of
the radiator is the highest point in the engine bay, remove the radiator
cap, start the engine and allow the engine to warm up to operating
temperature.  You should see bubbles escaping from the radiator opening.
When no more bubbles appear (wait another 2 minutes cause they like to hide)
replace the cap and go for a drive around the block watching the temp gauge
for signs of overheating.  If it rises above the midpoint, go back an
rebleed the system.   If the temp needle is stable, you're a hero!  

Think horses, not zebras,

Ron Sanders
email: RLS5@domain.elided
'92 525i
'93 325is

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