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2006 K1200GT Cooling Issue - Help!

chrisinsc

Member
I worked on a friends K1200GT this weekend. He had put in a new radiator before riding from Fresno to King City last Friday afternoon. While riding Saturday it overheated and coolant was puking out the left side of the bike. He had it dropped at my place and rode my RT back home to come back this week and trailer it back home etc.

Yesterday I took messed around with it and found the big spring clamp on the upper left big hose exiting the radiator was not on and sitting in the middle of the hose and a bunch of grey grease like material dripping down the left edge of the radiator. Also, only about a quart of nasty grey fluid came out of the system when I drained it.

So, I poured some distilled water into the radiator and rinsed it out best I could, put the clamp back on, checked all hose and wire connections I could see and carefully put the correct amount of coolant into the system.

I then performed a number of heating cycles at idle where I would then shut it down when the fan came on and then let it cool to ambient on the side stand. After the third cycle, the radiator stayed full.

However, during these cycles I could not get the upper left big hose connection on the radiator to stop weeping. I massaged it, greased the outside of the hose, and eventually put a big screw style clamp on it but the pressure in that location was too high. On the road the temp gauge would not read higher than 1/4 but when stopped at the end of the short test rides the temp climbs quickly to 1/2 and the fan comes on. At this point its clear there is a lot of pressure in the system at that hose location.

I am sure I have the system 100% filled with coolant. Is this a thermostat issue? It seems like coolant is not circulating properly.
 
What method did you use to fill the system? Those bikes have the rad cap lower than the top of the engine and cannot be fully filled through the cap. You have to vacuum fill the system through the reservoir. The exact procedure is in the factory service manual.
 
Thanks for the response!

Radiator cap on the side stand is the highest point in the system as far as I can see. I read all the stuff about the vacuum process but I got 2.55 liters of coolant into it eventually by using the bleeder on the water pump, time, and heating/cooling cycles. It wont take any more coolant. I kept careful track of the amount of coolant that has gone into the bike. Even captured the amount that came out of the bleeder etc.

I guess its possible that it really takes more than 2.55 liters...
 
What coolant was put into the bike with the new radiator? The gray spooge you describe sounds like a possible incompatible coolant mix. The correct coolant is available through a BMW dealer.

As for filling the system, the vacuum procedure is the only guaranteed method for preventing trapped air pockets in the coolant passages. Some have reportedly gotten around those by tilting a running and warmed-up bike to both sides. If you get trapped air at the sensor location an accurate temp reading is unlikely to be attained.

Best,
DeVern
 
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As for filling the system, the vacuum procedure is the only guaranteed method for preventing trapped air pockets in the coolant passages.
Best,
DeVern

Vehicle engines have had liquid cooling for more than 100 years, since the turn of the 20th century. I have to ponder why BMW designed a system that pouring in coolant isn't good enough? It sounds like a complete lack of forethought to me. That engine isn't so different that a special way to fill it with coolant ought to be necessary. Or is it??
 
Vehicle engines have had liquid cooling for more than 100 years, since the turn of the 20th century. I have to ponder why BMW designed a system that pouring in coolant isn't good enough? It sounds like a complete lack of forethought to me. That engine isn't so different that a special way to fill it with coolant ought to be necessary. Or is it??

I thought most modern car engines require a vacuum fill.
Maybe it has to do with making engines more compact and light weight requiring very small passageways.
 
I think designers finally traded an esoteric method of filling for the ability to put a radiator/s anywhere they want. I will lean bike way over and see if that does anything.

the grey material was like a very thin grease
 
Vehicle engines have had liquid cooling for more than 100 years, since the turn of the 20th century. I have to ponder why BMW designed a system that pouring in coolant isn't good enough? It sounds like a complete lack of forethought to me. That engine isn't so different that a special way to fill it with coolant ought to be necessary. Or is it??

Well, newer engines are indeed quite different, with much smaller coolant passages in many cases. But two other issues factor in as well-- the ability to relocate the radiator to some position other than with the fill point as the highest point in the system, and the ability to pressure-test the system at the same time and with the same hardware as when it's being filled.

if this diagram is correct then the thermostat was in upside down

The factory service manual shows this:
(+) Installing thermostat

Install thermostat (1) and thermostat housing (2).
K43HV_R17017b_preview.jpg

Best,

DeVern
 
Well, newer engines are indeed quite different, with much smaller coolant passages in many cases. But two other issues factor in as well-- the ability to relocate the radiator to some position other than with the fill point as the highest point in the system, and the ability to pressure-test the system at the same time and with the same hardware as when it's being filled.



The factory service manual shows this:
(+) Installing thermostat

Install thermostat (1) and thermostat housing (2).
View attachment 84963

Best,

DeVern

Thanks very much, always nice to see two competing diagrams! I think will have to defer to the factory manual so I guess the missing brass bit is down in the radiator.
 
Is piece #1 in the factory diagram loose or does it press fit in piece #2?

In other words, when removing a "good" thermostat do you have to be careful to pull both parts out at the same time to avoid the brass bit falling into the radiator or is it essentially one part?
 
So, my friend got a new radiator/thermostat and is installing it.

does the 2.55 l capacity of the system include the coolant in the remote container to the max line?
 
On Vacuum Filling...

When I started doing the maintenance on our past ’08 K1200GT, I quickly found out that lots of stuff had to be removed to get to anything other than the standard engine oil and rear drive drain plugs…like the radiator.

The first time I did a radiator pull to get to the plugs and valves I got lucky after a bunch of tries and successfully “burped” the system. There is a “burp” plug on the water pump side, a plastic vent plug.

Before the second time around with the radiator, I bought an Airlift Radiator Tool. I didn’t realize at the time that I bought the cheapest version. It was way difficult to use, and I produced several radiator fluid "clouds" in my shop.

After the addition of a couple of cutoff valves it was way easier to use and cut the radiator fill time to a few minutes. An air compressor that can hit 90psi is needed.

It would seem that a vacuum tool of some kind is needed to service many modern engines' cooling systems, and, considering how important the cooling system is on most modern engines, a vacuum test each time the fluid is drained makes good sense.

I like having the right tool for the job and the Airlift Radiator Tool I bought did the job, once modified. The newer versions all seem to have the cutoff valves in place like the ones I installed.

On the other hand, draining and filling the two radiators on our 2002 K1200RS is like old times…open the filler cap, pull off the lowest pipe, let the fluid gush out, put the pipe back on, fill, burp the top hose, fill, put the filler cap back on...done. The filler cap is at the top/highest point of the cooling system so gravity does all the work.
 
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