New to this forum - qstn @ coolant

[TCDRong]

Dear all,
I am new to BMW and new to this forum, too.

I just bought a '91 BMW 318is for about 3 weeks. Since therer is not much history of the car from the previous owner, I decided to change the coolant, because the s/o in the forum said the weak point of BMW car is the coolant system. I followed the instructions from Chilton's manual as well as those in this forum to drain, replace and bleed the coolant. And I believe I did it right.

Result: the temp gauge acts really weird: it jumps like crazy and most of the time toward 1 or 2 o'clock position! The fan seems to work normally (the speed same as when starting the car), the coolant doen't seems boil up. I tested the heater, it worked fine. The car run pretty OK, though.

Just about 2 days ago, when I tested the radiator hoses, I was really shocked there is no pressure! No leak visible from the hoses, not anywhere. The coolant is clean, and the oil is not milkey. But it lose the coolant a little bit, though.

Can someone advise what's wrong with my car and what I should do to fix this problem. Thank a bunch.


P.S.: I wanna add some clue after reading some other threads: when the temp gauge was at 2 o'clock position, I open the coolant extension cap: the coolant doesn't seem to boil. Look very normal as when I first brought the car home 3 weeks ago. Any sugggestion. I am really desperate....