2005 Other BMW Models Cooling fan cuts in to early cooling h

Tiny
JOHN BORRELL
  • MEMBER
  • 2005 BMW
  • 4 CYL
  • 2WD
  • MANUAL
  • 30,000 MILES
Sorry but I have a bike a BMW 650, but i'm sure that you can point me in the right direction.
I noticed the other day that the cooling fan was cutting in even if the bikes only been idling from cold for no more then 5 mins. I have removed the thermostat thinking that the water was not circulating. Another symptom is that the cooling hoses seam to be under a lot of pressure, normally you can squeeze the hoses, but once the engine is warm it is impossible, the longer ones look bloated. There is no oil in the cooling liquid or any significant loss of cooling liquid or oil. I must point out the the bike doesn’t overheat even in traffic but I can feel that it is warmer then usual.
A mechanic told me that the pressure in the cooling system is due to a leek in the cylinder head, causing pressure to pass from the cylinder to the cooling system. I find that hard to believe. First because the bike only has 30 k miles on the clock and also because it has never over heated of run low on water or oil. And there is no oil in the cooling liquid
Somebody told me that there is a way, with a liquid, of testing if there is a leek in the head gasket. Can you tell me where/how I can do this test? The bike is being brought back home on a recovery van and once I get it back I would like to my hands on it
Thanks from Sunny Spain
John Borrell
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Monday, August 18th, 2008 AT 4:20 AM

3 Replies

Tiny
DOCHAGERTY
  • EXPERT
The mechanic has a point. Excessive pressure in the cooling system could be a compromised head gasket or perhaps something worse(cracked head casting) Start with a cooling system pressure test. Let it sit overnight with the spark plug out and see if coolant is seeping into the combustion chamber. There is a chemical test for the cooling system for detection of combustion gases in the coolant. The tool makers (Snap-on, Mac etc.) Can get you going on that. Don't run the motor without a thermostat, the system needs to operate the way it was designed, and not without the thermostat!
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Monday, August 18th, 2008 AT 10:23 PM
Tiny
JOHN BORRELL
  • MEMBER
Thanks I'm still waiting for the bike to get back. As soon as it is i'll get my hands on it.
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Tuesday, August 19th, 2008 AT 12:19 PM
Tiny
DOCHAGERTY
  • EXPERT
Let us know, keep in touch.
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Tuesday, August 19th, 2008 AT 2:26 PM

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