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After researching this forum and reading about having to pressurize the cooling system I have a question. Can you add fluid to the radiator without having to re-pressurize the cooling system? I own a '04 K1200GT and sometimes it runs hot (needle close to red line). I have already checked the overfill container and made sure it was filled to the right level. I have not taken the cap off the radiator yet. Any help greatly appreciated.
Thank you, 2ndChance :dunno:
 

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I think you may be getting confused because the latest bikes need some pressurisation procedure to get coolant in the system. Cooling systems aren't like your tires!

Our cooling systems have a reservoir sitting slightly higher than the radiator cap, but the level in the reservoir is not necessarily the important true level in the radiator because you can get air or a large air bubble trapped. In my experience this is more likely to be at the top of the right radiator where there's no cap.

The trick is to remove the left rad cap (carefully!) when the system is warm (but not hot!) and burp or squeeze the bottom hoses. I've also disconnected the top hose where it runs to the left rad and 'injected' coolant into the right rad with a baster, whilst burping the hoses. Before removing the radiator cap, pinch the small reservoir hose coming into the left rad with a pair of grips to close it off. This stops the reservoir coolant pouring out and leaving air in the pipe to be purged out.

Finally, there will be some air left at the top of the radiators. Top up the reservoir to normal and run the bike up to 'fans on' at idle and allow to cool 1/2 hour whilst watching the reservoir. Make sure the front of both radiators feels hot at 'fans on'. If the right rad feels cold, then you have a faulty thermostat, blockage or a big air bubble in there. The reservoir level will rise, sometimes air bubbles will work through, then as the motor cools the level will drop. Do this a couple of times. You should do this every time you remove the cap (and let air in). There have been reports of pressure caps going faulty and not sealing properly so the system won't pressurise when hot and pukes coolant out of the reservoir - a cheap fix to replace and good insurance.

The problem with the K bike cooling system, is they didn't put a bleed hole in the thermostat under the right rad. This means when the motor is cold and it's closed , you cannot get coolant across to the right rad that you pour in through the left rad pressure cap or reservoir.



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Discussion Starter #3
Voxmagna,
Thank you for the quick reply. :clap:
I live in Las Vegas where it gets really, really hot during the summer months. I would like to work on the cooling system now before it gets to hot.
Do I need to remove the plastics bits to do what you ae recommending? Are you also saying that our cooling systems are different from cars?
 

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Running close to the red is normal..."they all do that"....close to over heating and over heating are very different.....your expantion tank is filled to the proper level....both fans kick on...the outside of the radiator is free of junk...(good air flow)... your boiling point and freeze protection is good.......you should be good to go.....
 

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2ndChance said:
Voxmagna,
Thank you for the quick reply. :clap:
I live in Las Vegas where it gets really, really hot during the summer months. I would like to work on the cooling system now before it gets to hot.
Do I need to remove the plastics bits to do what you ae recommending? Are you also saying that our cooling systems are different from cars?
The cooling system isn't that different compared to cars, but the actual water flow directions are a bit strange and there is a tendency to get trapped air in the right radiator. But the radiators are smaller (bikes are mean't to be running fast most of the time!). You could make sure that both radiators are clear of obstruction from squashed bugs so there is a good airflow.

You can reach the left rad cap without removing plastic but it starts to get awkward if you need to undo the hose clips.

Provided the guage doesn't run higher than red, you are probably best feeling both rads at the front to make sure their temperatures are similar from 1/2 way up the guage. The guage works over quite a narrow temperature range, so red isn't many degrees above mid way.



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Although I live in a cooler enviorment, my K12RS runs hot as well. I have found that a coolant flush with 60% distilled water and 40% BMW coolant with 1/2 bottle of Redline Water Wetter makes a nice difference.

Drain the coolant by removing the lower radiator hose and then run some fresh water through to wash out all the old coolant.

The trick is when you re-fill your coolant from the filler hole is to add the coolant VER SLOWLY, and stop often to burp the system by squeezing the lower radiator hose, then eventually work you way up to the crossover hose between to two radiators.

Once topped off run the bike until the fans come on, re-burp and fill to the neck. Then you are all set.

I forgot to mention that the job requires the removal of your belly pan and left side tupperware. Carefully done, it is a 3 to 4 hour job, but well worth it!

Pete
 

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My son has a 98 KRS...he is using a fan switch from a VW...rabit or something that just screws in to radator but is 15-20 deg.cooler so fans come on sooner.....he has also used a toggle switch to cut fans on when he wants them to on another k-bike.Not bypassing normal workings....I have an 03 K GT but mine seems to come on well before the RED .
 

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westcoastbiker said:
My son has a 98 KRS...he is using a fan switch from a VW...rabit or something that just screws in to radator but is 15-20 deg.cooler so fans come on sooner.....he has also used a toggle switch to cut fans on when he wants them to on another k-bike.Not bypassing normal workings....I have an 03 K GT but mine seems to come on well before the RED .
Yes, I thought about fiddling the oem temperature sensor, but the fans are actually switched by the ECU in response to the cyl head sensor which tells the ECU to do other things as well.

Since the oem fans cost a fortune and don't last that long on most bikes, I decided extra 'huff' cutting in at a lower temperature from cheaper aftermarket fans might be better. I'll probably use the temperature guage sensor.

Reducing the anti freeze concentration to 40% should give an improvement, but you could lose out on the anti corrosion inhibitors. With a lower concentration I'd change the coolant more often.



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