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Swapping in fresh coolant and heard a brief mention of a preferred drain location other than the large coolant hose. The speaker was not specific but said it was in the same area as where the main coolant hose connects to the block. I'm reluctant to take the main hose off because they are more prone to leaks. Does anyone know of this alternate drain location and perhaps have some images to guide me? Also, do I need to drain the system at more than one location? Thanks as always for the help.
 

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Swapping in fresh coolant and heard a brief mention of a preferred drain location other than the large coolant hose. The speaker was not specific but said it was in the same area as where the main coolant hose connects to the block. I'm reluctant to take the main hose off because they are more prone to leaks. Does anyone know of this alternate drain location and perhaps have some images to guide me? Also, do I need to drain the system at more than one location? Thanks as always for the help.
There are 2 methods commonly used to drain the old coolant on these K1200RS-GT and K1200LT. Believe it or not... even BMW is confused as they say to use method 1 below in their K1200RS shop manual. On the other hand, they say to use method 2 in their K1200LT shop manual. In the CLYMER shop manual for K1200RS-LT, they basically repeat / copy from the BMW books: if you have a K1200RS use the hose - if you have a K1200LT remove the coolant temp sensor (more on this below).

To me this is non sense as the engines are the same on both. Of course the K1200RS has an added flange for oil cooler hoses between engine block and oil-water pump, but this does not affect the amount of coolant or where it flows. This K1200RS oil cooler flange only affect the total amount of oil entering / circulating in the system.

Method 1: remove the large hose connecting the right radiator TO the the water pump inlet below. Be prepared with large container as coolant will rush out very fast. Only issue with this method is the fact it leaves about 1/2 cup that stays in the pump.

Method 2: Disconnect wire from engine coolant sensor located below water-oil pump assy. Then remove / unscrew this temp sensor (this feeds only the temp gauge on dash - not the engine computer). This will drain more slowly than method 1 above as the size of the hole / threads is only 10 mm (the wrench needed is 14 mm). See photo below taken on a K1200LT - same water-oil pump but no hoses for oil cooler. IF you use this method , be very careful as there has been a few cases (over last 15 years in many forums) where the sensor threads would be seized in the water pump assembly because of corrosion. If previous owner / or previous mechanic was always using method 1 instead, over time this sensor will seize there when not moved.

Using either method, it is important to remove the radiator cap FIRST to help the liquid go out. It has been my experience that the system is difficult to fill completely unless you:
(A) fill slowly when parked on center stand
(B) massage the lower hose connecting both radiator as you approach being full visually in the cap hole
(C) when full , close the cap properly and run the engine once on center stand until the fans will start - let it cool down overnight.
(D) after the engine has cooled down to room temperature, open the cap again (on center stand) and fill just enough to be able to install cap without overflowing out of cap.
(E) When engine is cold, set overflow tank under seat between MIN and MAX. I avoid filling to MAX when cold as the overflow tank level can go up as much as 1 inch when engine is very hot (after fans start).

Personally I have always used method 1 for emptying the coolant since new (about every 3 years on average). It is only a few years later that I learned about method 2 (when the CLYMER manual was published). Around 2010 when I saw a few issues on K1200LT forums with the sensor being seized and causing damage to water pump, I became convinced I would never remove the sensor unless it was defective.

I would rather buy a new connecting coolant hose that may get a bit worn by the pulling / removal over 20 years THAN having to deal with a sensor that breaks inside the water-oil pump assembly. I have seen pictures of the damage / corrosion on the K1200LT forum - it was not pretty...


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Discussion Starter · #3 ·
There are 2 methods commonly used to drain the old coolant on these K1200RS-GT and K1200LT. Believe it or not... even BMW is confused as they say to use method 1 below in their K1200RS shop manual. On the other hand, they say to use method 2 in their K1200LT shop manual. In the CLYMER shop manual for K1200RS-LT, they basically repeat / copy from the BMW books: if you have a K1200RS use the hose - if you have a K1200LT remove the coolant temp sensor (more on this below).

To me this is non sense as the engines are the same on both. Of course the K1200RS has an added flange for oil cooler hoses between engine block and oil-water pump, but this does not affect the amount of coolant or where it flows. This K1200RS oil cooler flange only affect the total amount of oil entering / circulating in the system.

Method 1: remove the large hose connecting the right radiator TO the the water pump inlet below. Be prepared with large container as coolant will rush out very fast. Only issue with this method is the fact it leaves about 1/2 cup that stays in the pump.

Method 2: Disconnect wire from engine coolant sensor located below water-oil pump assy. Then remove / unscrew this temp sensor (this feeds only the temp gauge on dash - not the engine computer). This will drain more slowly than method 1 above as the size of the hole / threads is only 10 mm (the wrench needed is 14 mm). See photo below taken on a K1200LT - same water-oil pump but no hoses for oil cooler. IF you use this method , be very careful as there has been a few cases (over last 15 years in many forums) where the sensor threads would be seized in the water pump assembly because of corrosion. If previous owner / or previous mechanic was always using method 1 instead, over time this sensor will seize there when not moved.

Using either method, it is important to remove the radiator cap FIRST to help the liquid go out. It has been my experience that the system is difficult to fill completely unless you:
(A) fill slowly when parked on center stand
(B) massage the lower hose connecting both radiator as you approach being full visually in the cap hole
(C) when full , close the cap properly and run the engine once on center stand until the fans will start - let it cool down overnight.
(D) after the engine has cooled down to room temperature, open the cap again (on center stand) and fill just enough to be able to install cap without overflowing out of cap.
(E) When engine is cold, set overflow tank under seat between MIN and MAX. I avoid filling to MAX when cold as the tank level goes up at least 1 inch when engine is fully warmed up.

Personally I have always used method 1 for emptying the coolant since new (about every 3 years on average). It is only a few years later that I learned about method 2 (when the CLYMER manual was published). Around 2010 when I saw a few issues on K1200LT forums with the sensor being seized and causing damage to water pump, I became convinced I would never remove the sensor unless it was defective.

I would rather buy a new connecting coolant hose that may get a bit worn by the pulling / removal over 20 years THAN having to deal with a sensor that breaks inside the water-oil pump assembly. I have seen pictures of the damage / corrosion on the K1200LT forum - it was not pretty...


View attachment 31537
Thanks Sailor.
 

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Thanks Sailor.
If you feel confident to do maintenance yourself, I STRONGLY SUGGEST you buy the CLYMER repair manual for K1200RS / K1200LT. It is fairly cheap, about $US45 , considering the value you will get.

Nowadays even a simple job will cost you at least $100 at the dealer.
For 95% of the jobs , the CLYMER repair manual is better and includes more photos (and more tips) than the BMW factory shop manual - I have both.
 
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I like the hose method.But make sure it is repositioned correctly, a slight twist at the clamp can bring the hose forward a touch and it may contact the belly pan fastener/clip and wear.Screw should be a short one.

It may not look like it contacts at rest on the stand but riding at speed there can be enough pressure to push the fastener/clip against the hose.
 
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I like the hose method.But make sure it is repositioned correctly, a slight twist at the clamp can bring the hose forward a touch and it may contact the belly pan fastener/clip and wear.Screw should be a short one.

It may not look like it contacts at rest on the stand but riding at speed there can be enough pressure to push the fastener/clip against the hose.
Your post above is a very good point that I forgot to mention in my long reply ;-)

After about 8 years since new, I did in fact change the large lower hose because I found out the screw OR the fastener on the belly-pan had worn a spot into it. As you have said, just being carful to keep proper angle when reinstalling / pushing the hose into the pump inlet made a difference for me.
 

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That angled edge of the clip was probably the culprit? I remember rounding it off on the bench grinder as an extra caution.At 21psi cooling system pressure them hoses most probably expand some.
 

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Your post above is a very good point that I forgot to mention in my long reply ;-)

After about 8 years since new, I did in fact change the large lower hose because I found out the screw OR the fastener on the belly-pan had worn a spot into it. As you have said, just being carful to keep proper angle when reinstalling / pushing the hose into the pump inlet made a difference for me.
8 years is a good lifetime!
 

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After about 8 years since new, I did in fact change the large lower hose because I found out the screw OR the fastener on the belly-pan had worn a spot into it. As you have said, just being carful to keep proper angle when reinstalling / pushing the hose into the pump inlet made a difference for me.
8 years is a good lifetime!
For an OEM black rubber BRAKE hose (as they came from factory) , 8 years is enough and they need to be changed soon... There is enough data / past evidence to show a higher rate of failure past 10 years on these Brake hoses.

HOWEVER there has been very few failure of these OEM coolant hose on K1200RS although some are more than 20 years old and still running. As a preventive measure, I would suggest to change after 20 years, but in my case it was another issue that had motivated the replacement of a single hose.

At your dealer, the OEM replacement coolant hoses are sold separately and the sum of all these parts is currently $US$ 346 - ouch !! Some owners on the K1200LT forums have tried a 3rd party replacement set with some success.

These 3rd party replacement radiator hoses also fit the K1200RS and are being sold as a set on EBAY by a seller called "as3performance" for about $US$ 100 plus shipping from UK. If you are located in USA, you may get faster / cheaper shipping from our good friends at "Euro Motoelectrics" for this kit: Complete Radiator Hose Kit - BMW K1200GT, K1200LT, K1200RS ADV / AS3
 
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I would rather buy a new connecting coolant hose that may get a bit worn by the pulling / removal over 20 years THAN having to deal with a sensor that breaks inside the water-oil pump assembly. I have seen pictures of the damage / corrosion on the K1200LT forum - it was not pretty...


View attachment 31537
The one in that picture certainly looks new enough!
 
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