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Discussion Starter #1
Hello, having a problem with my 1998 k1200rs where the fuse for the radiator fans is blowing out. Replacement of the fuse did not resolve, blew once bike got hot. Tested both fans by applying 12v & both spun with no issues. Both fans do not seem to be warped & are clearing shroud. Replaced fan relay with same results (blown fuse) fans not coming on. When bike runs & gets hot both radiators are hot & beleive they are equally hot, hose to waterpump is hot as well as hose that cncts both tanks. Radiator fluid was replaced last season & tested ok & is filled between to max in overflow tank. If anyone has any information on how & what to test next it would be much appreciated...thx
 

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One thing that may save you some time:
I learned how to run the fans without having to heat up the bike.
Simply disconnect the connector under the seat that leads to the temperature sensor in the head (rear of the engine). It is closest to the tank on the left side. It has two wires (purple and Brown with yellow stripe on my 2002s).

When you disconnect this, with the key on, side-stand up, in Neutral, the ECU instructs the fans to blow. If you pop the fuse, I'd disconnect the fans and check out the relay and wiring to the fans.
 

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KP24 said:
If anyone has any information on how & what to test next it would be much appreciated...
Here's a couple of questions to ponder - between the time the fuse didn't blow and the instance when fuses started to blow, did anything change (added something, or fiddled with something)? And if so, what was it?
 

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Discussion Starter #4
kniewiderstand said:
One thing that may save you some time:
I learned how to run the fans without having to heat up the bike.
Simply disconnect the connector under the seat that leads to the temperature sensor in the head (rear of the engine). It is closest to the tank on the left side. It has two wires (purple and Brown with yellow stripe on my 2002s).

When you disconnect this, with the key on, side-stand up, in Neutral, the ECU instructs the fans to blow. If you pop the fuse, I'd disconnect the fans and check out the relay and wiring to the fans.
Ok, sounds good i'll check it out ....thx
 

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Discussion Starter #5
carnadero said:
Here's a couple of questions to ponder - between the time the fuse didn't blow and the instance when fuses started to blow, did anything change (added something, or fiddled with something)? And if so, what was it?
did not add or fiddle...overheated first time when I got stuck in traffic, noticed horn stopped working about the same time. I figured the fuse blew & it did. Replaced & continued to blow, replaced $12.00 fan relay hoping for an easy fix (after testing fans) & it was a no go.
PS fans did work prior to getting caught in traffic that day
 

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Discussion Starter #6
carnadero said:
Here's a couple of questions to ponder - between the time the fuse didn't blow and the instance when fuses started to blow, did anything change (added something, or fiddled with something)? And if so, what was it?
did not add or fiddle...overheated first time when I got stuck in traffic, noticed horn stopped working about the same time. I figured the fuse blew & it did. Replaced & continued to blow, replaced $12.00 fan relay hoping for an easy fix (after testing fans) & it was a no go.
PS fans did work prior to getting caught in traffic that day
 

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Discussion Starter #7
kniewiderstand said:
One thing that may save you some time:
I learned how to run the fans without having to heat up the bike.
Simply disconnect the connector under the seat that leads to the temperature sensor in the head (rear of the engine). It is closest to the tank on the left side. It has two wires (purple and Brown with yellow stripe on my 2002s).

When you disconnect this, with the key on, side-stand up, in Neutral, the ECU instructs the fans to blow. If you pop the fuse, I'd disconnect the fans and check out the relay and wiring to the fans.
great info, I did what you suggested disconnected at sensor & fuse blew.
I disconnected both fans & fuse did not blow.
I connected each fan by itself, when i connected only the right side the fuse did not blow.
When I connected left side fan only, fuse blew.
I then connected the fan from the right side to the left side wiring & it was fine, did not blow the fuse.

The one thing that I don't understand is why when I hooked the left fan directly to 12v did it spin with no issues? Maybe it on its way out & was heating up the wires enough to blow the fuse?

Anyhow thanks a lot it sounds like I need to replace that fan. Do you know if the fans are normally swapped in pairs? Also where I might be able to pick them up for a good price?
Thanks
 

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KP24 said:
great info, I did what you suggested disconnected at sensor & fuse blew.
I disconnected both fans & fuse did not blow.
I connected each fan by itself, when i connected only the right side the fuse did not blow.
When I connected left side fan only, fuse blew.
I then connected the fan from the right side to the left side wiring & it was fine, did not blow the fuse.

The one thing that I don't understand is why when I hooked the left fan directly to 12v did it spin with no issues? Maybe it on its way out & was heating up the wires enough to blow the fuse?

Anyhow thanks a lot it sounds like I need to replace that fan. Do you know if the fans are normally swapped in pairs? Also where I might be able to pick them up for a good price?
Thanks

Glad you solved your problem. Buy your fans separately. Check the prices at Chicago BMW or Hammersly BMW, these dealers seem to have the best prices.

ps. Where the heck is Kendall Park?
 

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K1200 fan problem

There was a service action on K1200 fans not long after your bike was built. Cooling fans were supposed to be replaced on a VIN range, with improved fans having a blue dot on their frame. It's a bit late for warranty help, but I'm curious whether your bike slipped through the cracks.
 

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Discussion Starter #10
brucecha said:
Glad you solved your problem. Buy your fans separately. Check the prices at Chicago BMW or Hammersly BMW, these dealers seem to have the best prices.

ps. Where the heck is Kendall Park?
Thx so I'll only replace the one thats bad thx...Kendall Park is between New Brunswick & Princeton NJ
 

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KP24 said:
The one thing that I don't understand is why when I hooked the left fan directly to 12v did it spin with no issues? Maybe it on its way out & was heating up the wires enough to blow the fuse?
If it's like any run of the mill DC motor, maybe some of the armature's windings are shorting out.

What say you, Vox?
 

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Yes, When the fans were 'tested' on a battery the dc current should also have been checked. They may appear to 'run', but with shorted armature windings or worn brushes shorting they could pull a lot more running current. More important is the current surge at turn on, which would be a lot higher and take out the fuse. He should also check the motor shaft is loose and spins easily. I'd also make sure there are no addons wired on the fuse feeding the fans. From what I remember they chose the fuse rating to pickup a stalled fan, not to set fire to the bike.

These fans are the only thing keeping the bike running in hot weather. On a bike just newer than mine (mine has the blue dots) I'd seriously think about replacing both fans with new.

After all, one dead fan blowing fuses is 2 dead fans. Note to myself: must look at wiring diagram, did they fuse each fan separately, or were they stupid and only put in one fuse? If they were stupid, put an inline fuse in each fan supply. With care, a bike should run with one fan out.

When you get the new fan(s) - cut open the old one and tell us what you see.



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Discussion Starter #13
54089093 said:
There was a service action on K1200 fans not long after your bike was built. Cooling fans were supposed to be replaced on a VIN range, with improved fans having a blue dot on their frame. It's a bit late for warranty help, but I'm curious whether your bike slipped through the cracks.
just checked, both fans have a blue dot painted on rear of fans...thx
 

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One thing that may save you some time:
I learned how to run the fans without having to heat up the bike.
Simply disconnect the connector under the seat that leads to the temperature sensor in the head (rear of the engine). It is closest to the tank on the left side. It has two wires (purple and Brown with yellow stripe on my 2002s).

When you disconnect this, with the key on, side-stand up, in Neutral, the ECU instructs the fans to blow. If you pop the fuse, I'd disconnect the fans and check out the relay and wiring to the fans.

I know this post is from ages ago... but thank you for this test!

My question is though, if the fans do kick on in this test (is there any chance there is still an issue stopping them from coming on when bike is hot?) Thermostat maybe?

I just had bike serviced, and posed the question if it was possible to adjust when they kicked on (make it earlier) or kicked off (make it later) and they said my fans weren't kicking on at all.... and they could diagnose it for a cost.

The day before, I know they were running for a fact cause I felt and saw temp drop while stopped.

I had them flush and change coolant before they told me the fans weren't working, and bike runs colder now.

I did have a chance today to let it run and warm up twice, and fans kicked on both times.

So, seems everything is working afterall
 

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Does this help?
I would look for a short or a bad ground between all these components, if none, then i would remove the fan connectors, take a standalone 12v batteru and connect the fans one at the time connected via a multimeter and check the ampdraw, then both together.

Just because they move freely doesent mean they are not shorted internally.
 

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One of the cheapest and most effective ways to make your K run cooler and have the fans kick in a bit earlier is to remove the radiators and give them a really, really good clean. Years of road grime, bugs and small particles will block and reduce the air that passes through them. These radiators (and the fans) are barely adequate for the task and their capabilities quickly diminish when even slightly clogged. Just pushing a bit of water through them in situ wont cut it. And don’t be tempted to use compressed air or a water blaster - just DON’T go there - as the fine aluminium fins will fold in an instant. I pull my radiators every 3 or so years. I start by soaking them overnight in water and then give them a firm bang on a piece of cardboard to knock out debris. You will be amazed what comes out! Then I patiently work my way across each one straightening all the fins that I can and picking out or poking through all the debris left behind. Tedious work but the rewards are well worth it.
I made some simple and effective radiator guards using the same product custom car enthusiasts use. Cut it to match the width of the radiator and a little longer top and bottom. Gently bend a small top to bottom concave curve into the guard and slip it between the fins and the top/bottom fittings and they won’t rattle or fall out. Also made a guard for the oil cooler as a stone through any of these fragile items will leave you stranded.
 

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Old aluminium roasting pan and the vibrator thing from an old Lazyboy recliner.Set pan on foam blocks....stick vibrator under the pan.Put both radiators in the pan.....add soapy water and start the vibrator.Walk away from the noise overnight.Next morning most if not all the debris will be on the bottom of the pan.And maybe a fly or two floating on top?:grin

I like my DIY subsonic and maybe even ultrasonic parts cleaner.:smile

Seized up fan? Had one a couple years ago.Easy to fix and did the other one preventively.2 yrs ago or 60,000 kms,no problems!
 

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Old aluminium roasting pan and the vibrator thing from an old Lazyboy recliner.Set pan on foam blocks....stick vibrator under the pan.Put both radiators in the pan.....add soapy water and start the vibrator.Walk away from the noise overnight.Next morning most if not all the debris will be on the bottom of the pan.And maybe a fly or two floating on top?:grin

I like my DIY subsonic and maybe even ultrasonic parts cleaner.:smile

Seized up fan? Had one a couple years ago.Easy to fix and did the other one preventively.2 yrs ago or 60,000 kms,no problems!
I like this a lot. Time to update my methods :grin
 
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