steve l
Member
My bike now has 42,000 miles (68000Km) on the clock. During the last few years our annual trip round Spain has been marred by occasional overheating warnings from the bike. These occur when the bike is under heavy load at slow speed in temperatures above 30C (86F). The cooling system was circulating well and the fan working.
Having previously had the radiator removed and flushed inside and out, with some improvement, the radiator was again removed. It was found to be partially plugged with grit externally that was impossible to flush/jet out, (see photos). It would be laboriously time consuming to remove this grit by hand and I think this would likely damage the radiator.
I elected to fit a new radiator at a cost of £450 (UK Pounds). To prevent this happening in future I have further extended the front fender extender. To monitor the situation I fitted a digital coolant temperature gauge and fan warning lamp, (see photos). I should now be able to see the fan start at 95C and if necessary, take action to prevent the overheat warning at 115C. In my experience turning the bike off after the warning comes on, results in the loss of 500ml of coolant and a spectacular arrival at your hotel!
After fitting the new radiator the system was pressurised to 1.3 Bar (19psi) to check for leaks, the filler neck was found to be 2mm oval and a slight leak was found due to a defect in one O ring groove in the coolant line under the engine (see photos). Both items were replaced. This required the removal of the exhaust and oil cooler to provide clear access to the coolant line. The exhaust system is held on with special M7 x 10mm Bi-Hex nuts that it is advisable to replace with new. The oil cooler O ring (64 x 3mm) was not available from BMW and had to be specially made.
While discussing the issue with my local BMW dealer, it transpires a similar problem exists with the K1200/K1300 2004-2015 models that also has the radiator mounted low down behind the front wheel. They consider the K1200 radiator to be a “service item” requiring regular replacement.
Having previously had the radiator removed and flushed inside and out, with some improvement, the radiator was again removed. It was found to be partially plugged with grit externally that was impossible to flush/jet out, (see photos). It would be laboriously time consuming to remove this grit by hand and I think this would likely damage the radiator.
I elected to fit a new radiator at a cost of £450 (UK Pounds). To prevent this happening in future I have further extended the front fender extender. To monitor the situation I fitted a digital coolant temperature gauge and fan warning lamp, (see photos). I should now be able to see the fan start at 95C and if necessary, take action to prevent the overheat warning at 115C. In my experience turning the bike off after the warning comes on, results in the loss of 500ml of coolant and a spectacular arrival at your hotel!
After fitting the new radiator the system was pressurised to 1.3 Bar (19psi) to check for leaks, the filler neck was found to be 2mm oval and a slight leak was found due to a defect in one O ring groove in the coolant line under the engine (see photos). Both items were replaced. This required the removal of the exhaust and oil cooler to provide clear access to the coolant line. The exhaust system is held on with special M7 x 10mm Bi-Hex nuts that it is advisable to replace with new. The oil cooler O ring (64 x 3mm) was not available from BMW and had to be specially made.
While discussing the issue with my local BMW dealer, it transpires a similar problem exists with the K1200/K1300 2004-2015 models that also has the radiator mounted low down behind the front wheel. They consider the K1200 radiator to be a “service item” requiring regular replacement.
