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Subject: 'Check Coolant' warning and overheating today on the highway. Author: davidc (moderator) : member since December, 2003 : 10552 posts Posted on: 2004-12-29 13:36:40

Today the 'Check Coolant' message displayed on the instrument cluster as my wife was driving the '97 740iL (128,000 miles). The temp guage was at the redline so we immediately pulled over. The coolant leak appears to be coming from the right (passenger) side of the car, below the expansion tank. I don't think its the radiator, but I'm not 100% certain of that.

The leak appeared to be slow, so we called a friend who brought out a couple of gallons of water. With the engine running (to keep the cold water mixed with whatever hot coolant remained), we added about 1.5 gallons of water. I left the radiator cap loose to avoid pressurizing the system which would cause the coolant to leak more rapidly. For the 5 miles it took to get home, the temp gauge stayed in the normal vertical position and now the car sits in the garage.

Does this sound like the expansion tank? The radiator was replaced by the previous owner at 94,000 miles, but I don't think they replaced the expansion tank.

David Cecil, KI4GZR
'97 740iL, 127k miles
'92 750iL, 77k miles
'86 735i, 95k miles

www.e38.org has links for everything about your BMW 7-series automobile

• 'Check Coolant' warning and overheating today on the highway. - davidc 2004-12-29 13:36:40 (3086 views)
  • Update: Expansion tank removal and replacement procedure completed (url) - davidc 2005-01-07 19:59:29 (986 views)
  • Update: It was the expansion tank (url) - davidc 2005-01-02 16:06:48 (980 views)
  • It's never simple like a Rad hose on these cars Huh! (nt) - BJames38 2004-12-30 09:50:41 (512 views)
    • Check Coolant level - admills 2005-07-12 23:23:31 (747 views)
  • My coolant tank vent nozzle cracked last july. Lost about half of coolant but - Roy In GA 2004-12-30 00:19:32 (560 views)
  • Definately worth replacement. > - Magnum 2004-12-29 22:53:04 (503 views)
  • Yup thats it. Also buy a new cap when you replace the tank. (nt) - Gary 2004-12-29 19:09:11 (642 views)
    • Re: Yup thats it. Also buy a new cap when you replace the tank. - Gary 2004-12-29 19:13:07 (526 views)
      • Hey Gary did you see my post? (url) - silber98 2004-12-30 00:00:12 (433 views)
  • I called the indy I take my car to about this. I recall - Ultymte 2004-12-29 17:02:08 (484 views)
  • It does sound like the expansion tank. - farnarkler 2004-12-29 13:45:01 (449 views)
    • My expansion tank broke at the upper neck with.... - Northshore740 2004-12-29 14:33:19 (524 views)
      • Since you didn't mention a 'Ck Coolant Level' message, I'd count on it being ... - WTH 2004-12-29 17:09:37 (606 views)
        • I'm not sure how far she drove it hot. She didn't notice the temp needle. - davidc 2004-12-29 20:30:20 (441 views)
          • Didn't notice the mentioned 'Ck Clnt' warning msg in first post, this thread... (nt) - WTH 2004-12-29 22:19:20 (485 views)