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1Back to top Go down    Coolant overflow tank move/removal on Tue Sep 13, 2016 10:44 am

rxbbie

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Hi Guys,

So I'm sitting looking at my coolant overflow tank trying to decide what it's purpose is other than to act as a holding tank if there's too much pressure to the coolant. What I don't understand is there doesn't seem to be a outlet pipe feeding the coolant back in to the radiator?

I've been considering moving my coolant overflow from the usual position next to the battery to just below the coolant cap, would that do any harm?

    

2Back to top Go down    Re: Coolant overflow tank move/removal on Tue Sep 13, 2016 11:08 am

duck

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Same hose flows both ways as needed. If the radiator cap blows then it just makes a mess out the top and all over below it.

I don't think your bike will know if you move it or not.


__________________________________________________
Current stable:
86 Custom K100 (standard fairing, K75 Belly pan, Ceramic chromed engine covers, paralever)
K75 Frankenbrick (Paralever, K11 front end, hybrid ABS, K1100RS fairing, radial tires)
86 K75C Turbo w/ paralever
94 K1100RS
93 K1100LT (x2)
91 K1
93 K75S (K11 front end)
91 K75S
14 Yamaha WR250R
http://www.ClassicKBikes.com
    

3Back to top Go down    Re: Coolant overflow tank move/removal on Tue Sep 13, 2016 1:05 pm

rxbbie

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duck wrote:Same hose flows both ways as needed. If the radiator cap blows then it just makes a mess out the top and all over below it.

I don't think your bike will know if you move it or not.

Thanks for the reply. I didn't really explain my question very well earlier as I wrote it from my phone.. What I mean to say was it seems to just be a gravity feed allowing excess coolant to flow down into the overflow tank - so what provides the pressure for the coolant in the overflow tank to flow back into the radiator?

As for the question about moving my coolant tank.. I'll be moving it pretty much directly next to the cap. I'm just worried that the overflow tank being so close to the cap/pipe will cause some sort of problem if there ever is an issue with pressure build up?

    

4Back to top Go down    Re: Coolant overflow tank move/removal on Tue Sep 13, 2016 1:24 pm

Born Again Eccentric

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rxbbie wrote:Hi Guys,

So I'm sitting looking at my coolant overflow tank trying to decide what it's purpose is other than to act as a holding tank if there's too much pressure to the coolant. What I don't understand is there doesn't seem to be a outlet pipe feeding the coolant back in to the radiator?

I've been considering moving my coolant overflow from the usual position next to the battery to just below the coolant cap, would that do any harm?
Like Duck says - the hose allows flow in either direction. The clever bit is the radiator cap...see some detail at the following link:
http://www.k100-forum.com/t8299-radiator-pipe-suckage#97525

Heats up: Pressure increases, cap outlet valve opens and vents excess water to expansion tank
Cools down: Pressure drops, cap inlet valve opens (under slight vacuum) and allows system to suck water back from the expansion tank.

If the radiator cap is working properly (valves not fouled and/or seals not swollen and blocking the ports), you will notice very little flow to or from the expansion tank in normal operation.

If you are riding in hot weather, especially in slow moving heavy traffic and/or have a problem with the fan not working, then you are likely to get a flow to the expansion tank, which is OK as long as the expansion tank does not overflow and the cap is working properly to allow water to flow back to the radiator as the system cools down again.

I guess the main reason for the expansion tank being where it is normally located is so that you can easily see that the water is at the right level pre-ride and it is easily accessible to be able to top it up, if required. I don't see any reason why you couldn't move it just below the radiator cap - but there's not a lot of space there (the cap is already pretty inaccessible under the edge of the fuel tank). However, if you do go for a bit of a water carnival and end up overflowing the expansion tank (there's a little vent hole in its rubber cap), you will end up with hot water and steam blowing up in front of you (and probably soaking the all the electrics under the fuel tank) which is probably not very desirable while riding. In its current location, such an overflow event squirts the water and steam up under the seat and down the back of your right leg. Not good, but better than in your face! It doesn't happen very often, but I have experienced it once and I doubt if I am the only one to have had such an experience.


__________________________________________________

Paul

"Heidi" K100LT 1991 (Grey) (VIN 0190172 Engine No. 104EB 2590 2213) - 5th owner. January 2014 (34,000 - 61,000 miles and counting....)
"Gretel" K100LT 1989 (Silver Grey) (VIN 0177324 Engine No. 104EA 2789 2211) - 4th+ owner. September 2015 (58,500miles and counting....). Cat C Insurancewrite-off rebuild Feb 17
"Donor" K100LT 1990 (Red) (VIN 0178091 Engine No. 4489 2024) - 6th & final owner (crash write-off now donor bike). June 2012 (73,000 miles) to November 2013 (89,500 miles)
    

5Back to top Go down    Re: Coolant overflow tank move/removal on Tue Sep 13, 2016 1:40 pm

rxbbie

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Born Again Eccentric wrote:
rxbbie wrote:Hi Guys,

So I'm sitting looking at my coolant overflow tank trying to decide what it's purpose is other than to act as a holding tank if there's too much pressure to the coolant. What I don't understand is there doesn't seem to be a outlet pipe feeding the coolant back in to the radiator?

I've been considering moving my coolant overflow from the usual position next to the battery to just below the coolant cap, would that do any harm?
Like Duck says - the hose allows flow in either direction. The clever bit is the radiator cap...see some detail at the following link:
http://www.k100-forum.com/t8299-radiator-pipe-suckage#97525

Heats up: Pressure increases, cap outlet valve opens and vents excess water to expansion tank
Cools down: Pressure drops, cap inlet valve opens (under slight vacuum) and allows system to suck water back from the expansion tank.

If the radiator cap is working properly (valves not fouled and/or seals not swollen and blocking the ports), you will notice very little flow to or from the expansion tank in normal operation.

If you are riding in hot weather, especially in slow moving heavy traffic and/or have a problem with the fan not working, then you are likely to get a flow to the expansion tank, which is OK as long as the expansion tank does not overflow and the cap is working properly to allow water to flow back to the radiator as the system cools down again.

I guess the main reason for the expansion tank being where it is normally located is so that you can easily see that the water is at the right level pre-ride and it is easily accessible to be able to top it up, if required. I don't see any reason why you couldn't move it just below the radiator cap - but there's not a lot of space there (the cap is already pretty inaccessible under the edge of the fuel tank). However, if you do go for a bit of a water carnival and end up overflowing the expansion tank (there's a little vent hole in its rubber cap), you will end up with hot water and steam blowing up in front of you (and probably soaking the all the electrics under the fuel tank) which is probably not very desirable while riding. In its current location, such an overflow event squirts the water and steam up under the seat and down the back of your right leg. Not good, but better than in your face! It doesn't happen very often, but I have experienced it once and I doubt if I am the only one to have had such an experience.

Thank you, that clears everything up. The reason I'm trying to mount the overflow tank next to the cap is to create the minimalist look I'm going for with my cafe conversion. Definitely need to consider your point about it spilling on to the electrics under the tank though as the wiring is already a mess under there.

When I took the battery and coolant over flow tank out I noticed this pipe and cable lying loose. Do you have any ideas what they are? I've tried to show where they connect to in the photo attached. Cheers, Rob.

    

6Back to top Go down    Re: Coolant overflow tank move/removal on Tue Sep 13, 2016 1:53 pm

Born Again Eccentric

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Rob,

The hose possibly used to be connected to the battery vent - most modern maintenance free batteries don't need a vent hose because they are sealed.

I can't quite see where the wire you have highlighted in your photo goes to. The wire which goes through the grommet under the battery tray is the wire to the Gear Position Indicator switch (GPI) - and it doesn't look like it is part of that.



Last edited by Born Again Eccentric on Tue Sep 13, 2016 2:10 pm; edited 2 times in total (Reason for editing : Talking tosh!)


__________________________________________________

Paul

"Heidi" K100LT 1991 (Grey) (VIN 0190172 Engine No. 104EB 2590 2213) - 5th owner. January 2014 (34,000 - 61,000 miles and counting....)
"Gretel" K100LT 1989 (Silver Grey) (VIN 0177324 Engine No. 104EA 2789 2211) - 4th+ owner. September 2015 (58,500miles and counting....). Cat C Insurancewrite-off rebuild Feb 17
"Donor" K100LT 1990 (Red) (VIN 0178091 Engine No. 4489 2024) - 6th & final owner (crash write-off now donor bike). June 2012 (73,000 miles) to November 2013 (89,500 miles)
    

7Back to top Go down    Re: Coolant overflow tank move/removal on Tue Sep 13, 2016 2:22 pm

duck

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And while we're on the topic, radiator caps do go bad eventually. (Which I experienced on my 86 K75 turbo which caused several unnecessary and messy cap blows.) The radiator cap is only about $25 new from BMW so it is not a bad item to replace as regular maintenance after 30 years.


__________________________________________________
Current stable:
86 Custom K100 (standard fairing, K75 Belly pan, Ceramic chromed engine covers, paralever)
K75 Frankenbrick (Paralever, K11 front end, hybrid ABS, K1100RS fairing, radial tires)
86 K75C Turbo w/ paralever
94 K1100RS
93 K1100LT (x2)
91 K1
93 K75S (K11 front end)
91 K75S
14 Yamaha WR250R
http://www.ClassicKBikes.com
    

8Back to top Go down    Re: Coolant overflow tank move/removal on Tue Sep 13, 2016 7:32 pm

Holister

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Even cheaper is to just replace the radiator cap washer.... or just turn it over.


__________________________________________________
1988 K100RT VIN No. 0094680
1989 K100RT VIN No. 0097367 (naked)
1996 K1100RS VIN No. 0451808
Fuel: 95 Octane
Engine Oil:Nulon Full Synthetic 15W50
Gear Box Oil: Nulon Synthetic 75W90
    

9Back to top Go down    Re: Coolant overflow tank move/removal on Tue Sep 13, 2016 9:18 pm

duck

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There's a pressure activated spring inside the cap that can wear out. Next time you have it off to change the coolant take a look.


__________________________________________________
Current stable:
86 Custom K100 (standard fairing, K75 Belly pan, Ceramic chromed engine covers, paralever)
K75 Frankenbrick (Paralever, K11 front end, hybrid ABS, K1100RS fairing, radial tires)
86 K75C Turbo w/ paralever
94 K1100RS
93 K1100LT (x2)
91 K1
93 K75S (K11 front end)
91 K75S
14 Yamaha WR250R
http://www.ClassicKBikes.com
    

10Back to top Go down    Re: Coolant overflow tank move/removal on Wed Sep 14, 2016 12:43 am

Holister

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Didn't mean to imply that the cap didn't fail Duck, just that often it can be just a simple washer. I ordered a new washer for my 'Old Girl' and turned the old one around to get me by till the new one arrived (a suggestion back then by Olaf). 40k later and the old washer is still doing its job just fine.
Cheers


__________________________________________________
1988 K100RT VIN No. 0094680
1989 K100RT VIN No. 0097367 (naked)
1996 K1100RS VIN No. 0451808
Fuel: 95 Octane
Engine Oil:Nulon Full Synthetic 15W50
Gear Box Oil: Nulon Synthetic 75W90
    

11Back to top Go down    Re: Coolant overflow tank move/removal on Wed Sep 14, 2016 1:12 am

Dai

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The indicated black wire is the GPI switch lead. Should end in a four-pin connector - white for pre-86 bikes (tank connector front-left) and black for post-85 bikes (tank connector on a tail at the rear). Dates approximate - someone will be along to correct me soon Very Happy


__________________________________________________
'83 K100 upgraded to K100RS spec
Others...
'78 Moto Guzzi 850-T3, '79 Moto Guzzi 850-T3 California,'93 Moto Guzzi 1100ie California,
'03 Suzuki Blandit GSF600SK3 (NFS any more because wifey has claimed it)
    

12Back to top Go down    Re: Coolant overflow tank move/removal on Wed Sep 14, 2016 8:35 am

Born Again Eccentric

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Dai wrote:The indicated black wire is the GPI switch lead. Should end in a four-pin connector - white for pre-86 bikes (tank connector front-left) and black for post-85 bikes (tank connector on a tail at the rear). Dates approximate - someone will be along to correct me soon Very Happy
Dai - that's what I first thought...then I edited my answer (talking tosh) because, if you zoom in on the pic you can see that the mystery wire continues forward (and under) of the battery tray The bit you see under the tray and the loose end with missing connector appear to be the same colour...and a different colour & thickness to the GPI wire which goes through the grommet. It looks like the GPI wire curls around and goes into that blob of black masking tape and off to the the right hand side of the bike.


__________________________________________________

Paul

"Heidi" K100LT 1991 (Grey) (VIN 0190172 Engine No. 104EB 2590 2213) - 5th owner. January 2014 (34,000 - 61,000 miles and counting....)
"Gretel" K100LT 1989 (Silver Grey) (VIN 0177324 Engine No. 104EA 2789 2211) - 4th+ owner. September 2015 (58,500miles and counting....). Cat C Insurancewrite-off rebuild Feb 17
"Donor" K100LT 1990 (Red) (VIN 0178091 Engine No. 4489 2024) - 6th & final owner (crash write-off now donor bike). June 2012 (73,000 miles) to November 2013 (89,500 miles)
    

13Back to top Go down    Re: Coolant overflow tank move/removal on Wed Sep 14, 2016 9:07 am

Dai

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So it does.


__________________________________________________
'83 K100 upgraded to K100RS spec
Others...
'78 Moto Guzzi 850-T3, '79 Moto Guzzi 850-T3 California,'93 Moto Guzzi 1100ie California,
'03 Suzuki Blandit GSF600SK3 (NFS any more because wifey has claimed it)
    

14Back to top Go down    Re: Coolant overflow tank move/removal on Wed Sep 14, 2016 2:54 pm

blaKey

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Sticking my neck out here...

I rekon it's thelead for the accessory (merit) plug that sits on top of the cover for the coils.

Maybe?

It's a possibility?

Perhaps?

Could be?

Might be?


__________________________________________________
Neil
K100RS 1986 RED!
K100RT 1987 (now nekkid with red bits)

Remember Rule No. 6
    

15Back to top Go down    Re: Coolant overflow tank move/removal on Wed Sep 14, 2016 11:11 pm

Gaz

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If the mystery black tube/cable at the top of the photo is in fact part of the electrical system it might be useful to trim back a tiny bit of the outer covering to expose the colour coding on the cores. This will then be able to be identified from a coloured wiring diagram for the bike. The outer covering removed can be replaced by heat shrink when it is restored to it's proper function (or removed if the project requires).

I agree that the lower tube is battery vent pipe used on wet cell batteries.

Cheers


__________________________________________________
Gaz
95 K1100LT 0232224; 90 K75 6427509; 87 R80G/S PD 6292136
    

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