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Repair Guidance ~ On-Site / Re: reccomendation for vacuum filler for coolant
« Last post by frankenduck on November 29, 2022, 07:13:42 PM »
You really don't even need to burp it with the lower hose. If you undo the two 8mm nuts the hold the mounting for the radiator cap to the frame and hold that part up an inch or two then that allows the air right above the radiator to escape. That's how I've been doing it for years and never had an issue.

Even if there is some air in the cooling system then the cooling system tops itself off when the bike cools down. The radiator cap is just like that in a car. When the radiator cools down and creates a vacuum above 1.5 PSI it pulls coolant from the reservoir to top itself off.

In all my years of riding K bikes I've only had three cooling issues:

1 - Blew a hole in the big hose on the lower right on a K1100RS. Replaced the hose. (A few hundred miles after I'd changed the coolant and squeezed it - which is why I no longer squeeze radiator hoses and always carry a roll of Rescue Tape when touring.)

2 - Bad radiator cap that would blow too early on an 86 K75 with 125K miles. I could tell because the cap would blow before the coolant light in the cluster came on. Replaced the radiator cap and it's run fine ever since.

3 - Dead fan on a K1100LT. Rode another 2,000 miles. Just turned the bike off and if I had to sit in hot weather at a light. Then just restarted when the light turned green because as long as a K is moving at decent speed the fan isn't needed. Replaced the fan when I got home.
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Repair Guidance ~ On-Site / Re: reccomendation for vacuum filler for coolant
« Last post by The Mighty Gryphon on November 29, 2022, 07:10:22 PM »
In 50+ years so working on cars and bikes the only time I needed a vacuum filler was on a Mazda MX-5 which is well known for having passages in the block where air locks form to prevent coolant flow even when the engine is running. 
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Repair Guidance ~ On-Site / Re: reccomendation for vacuum filler for coolant
« Last post by Chaos on November 29, 2022, 06:56:08 PM »
I've used a vacuum pump to bleed the brakes but never needed anything other than gravity to change the coolant.
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Repair Guidance ~ On-Site / Re: reccomendation for vacuum filler for coolant
« Last post by The Mighty Gryphon on November 29, 2022, 06:29:17 PM »
The Duck is correct, you can fill about 95% of the cooling system just by slowly pouring the coolant in the filler and squeezing the hose on the lower right side of the engine to "burp" the air out. 

If you really want to pull a vacuum to purge all the "trapped" air, you can do it by sticking a vacuum cleaner hose in the filler for a few seconds.  I will leave it up to your creativity as to getting a seal and closing off the overflow hose to the bottle next to the battery.
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Repair Guidance ~ On-Site / Re: reccomendation for vacuum filler for coolant
« Last post by stokester on November 29, 2022, 06:25:33 PM »
I've never had any difficulty changing coolant using gravity.  Sometimes I have to add a bit to the overflow reservoir after the first ride.

Where in Hampton Roads are you?  I live near the Yorktown Battlefield.
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FS WTB WTT ~ Bikes ~ Parts ~ Gear / Re: WTB - K100RS handlebars
« Last post by Swampyankee on November 29, 2022, 05:37:00 PM »
Thanx! I was searching eBay specifically for k100rs bars which excluded those from my search results.
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Repair Guidance ~ On-Site / Re: reccomendation for vacuum filler for coolant
« Last post by frankenduck on November 29, 2022, 02:38:13 PM »
What makes you think that you need to have the motor running to change the coolant? You don't.
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Repair Guidance ~ On-Site / Re: reccomendation for vacuum filler for coolant
« Last post by Batkinson on November 29, 2022, 02:10:38 PM »
Yes, thanks

I have moved the k75 to a friendís heated attached garage so we can work on it, and he is seeking a way to change the coolant without the motor running because despite the big door being open the fumes go into his house.

This does not make his wife happy.

There are several videos online which show the use the of the vacuum filler and I am hoping to get some feedback as to one which works and any gotchas before moving on.

Thanks again tho
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Repair Guidance ~ On-Site / Re: reccomendation for vacuum filler for coolant
« Last post by frankenduck on November 29, 2022, 01:25:57 PM »
None.

Gravity works just fine and is the method recommended on Page 17-13 of the BMW K75/K100 Repair Manual.

http://www.kbikeparts.com/classickbikes.com/ckb.tech/0.ckb.tech.files/shopmanuals/BMW_K75_K100_Repair_Manual.pdf
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Repair Guidance ~ On-Site / reccomendation for vacuum filler for coolant
« Last post by Batkinson on November 29, 2022, 12:29:46 PM »
trying to revive a 92 k75 that has been sitting while i was unable to ride and am looking for recommended vacuum filler pumps for coolant..

 
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