ST1100 LLC leakage. how to separate FAN HARNESS

[ciliaris12]

i ordered genuine thermo SW just now
I can receive it tomorrow， very lucky

part number
thermo SW
37760 MT2 003
3830JPY

O-RING
9130761100
100JPY

THERMO SW is identical with my VFR800 RC46， it's interesting

addinng info.
Just now I received NOT genuine, compatible FAN SW.
the spec shows this compatible part have totally same spec with GENUINE one,

here's the boiling test resut to measure the ohm
very difficult to measure so the value is just as a reference.
the ohm value is 7ohm above 95 ℃
Also infinite resistance lower than 95℃
no variable ohm decrease. it's totally on-off control.
I hope genuine one's actual value also same.

 

[ciliaris12]

addinng info.
Just now I received NOT genuine, compatible FAN SW.
the spec shows this compatible part have totally same spec with GENUINE one,

here's the boiling test resut to measure the ohm
very difficult to measure so the value is just as a reference.
the ohm value is 7ohm above 95 ℃
Also infinite resistance lower than 95℃
no variable ohm decrease. it's totally on-off control.
I hope genuine one's actual value also same.

when the SW turn on, i could clearly hear click sound.

 

[dwalby]

hi dwalby
the photo might be taken slightly after the phenomenon, but i think this level of water temp. is too much high enough to make the water boiling and overflow abnormally for ST1100. FAN shoud have worked more earlier. if i remember correctly, this is the highest temp. that i've seen on my ST1100.
i don't want to try much more higher situation, i think it's too risky. but i understand you believe it's not critical, thank you for your advice.

Well, this is what I was afraid of, but its your decision.

you've apparently never allowed the coolant to get hot enough to close the switch, and for some reason you're afraid to allow that to happen.

you're claiming that the bike overheated because the fan never came on, but the temp gauge never went past vertical, which everyone on this forum knows isn't hot enough to turn on the fan much less overheat the coolant.

I think you're blaming the fan switch without actually testing it properly.

I wish you luck in your repair attempts.

 

[ciliaris12]

Well, this is what I was afraid of, but its your decision.

you've apparently never allowed the coolant to get hot enough to close the switch, and for some reason you're afraid to allow that to happen.

you're claiming that the bike overheated because the fan never came on, but the temp gauge never went past vertical, which everyone on this forum knows isn't hot enough to turn on the fan much less overheat the coolant.

I think you're blaming the fan switch without actually testing it properly.

I wish you luck in your repair attempts.

hi dwalby
when we design RADIATOR,

Well, this is what I was afraid of, but its your decision.

you've apparently never allowed the coolant to get hot enough to close the switch, and for some reason you're afraid to allow that to happen.

you're claiming that the bike overheated because the fan never came on, but the temp gauge never went past vertical, which everyone on this forum knows isn't hot enough to turn on the fan much less overheat the coolant.

I think you're blaming the fan switch without actually testing it properly.

I wish you luck in your repair attempts.

hi dwalby
i hope you to understand mechanical construction correctly though it's slightly difficult to understand, please do not judge by experience.
as an RADIATOR engineer, i can say FAN not worked but overflowed is apparently something is wrong.
LLC overflowed but FAN not working is apparently have trouble in your cooling system, and it's quite dangerous to leave it or test much more severe temperature. it will finally cost you unacceptable amount.

as you know our RADIATOR CAP spec is 1.25kgf/cm2 so if the pure water filled, the water temperature is around 123.8℃。this temperature is measured at thermo sensor located at the bottom of filler neck. slightly different temperature from RADIATOR's FAN SW, However the thermostat obviously full-open above 95℃ so basically both are similar, i think 5℃ difference at most because FAN SW is allocated at inlet of RAD.

Again, FAN MOTOR should have worked way much more earlier timing to avoid any engine trouble.however my ST1100 FAN did not worked while overflowing

process order is
1.engine temp mid
thermostat open, fan not work
2.engine temp high
thermostat full-open. fan work
3.engine temp too much high
thermostat full-open. FAN work, LLC overflow.

3. is sometimes happen while high temperature, severe engine use, after stopped engine.
however LLC overflow amount is small, never to leak from RESERVER TANK.

 

[ciliaris12]

when the SW turn on, i could clearly hear click sound.

I tried to exchange the FAN SW without detaching my COWLs, but it was impossible by my tools, Though i searched some short wrench , but not enough room to operate in this tight space. I will try disassembling related COWLs tomorrow.

 

[Uncle Phil]

If you are going to remove the upper cowling (where the mirror is attached), there is a bolt 'hidden' inside up near the head light.
It is a pain to get to (10MM IIRC) but if you don't you will crack the fairing.
Once I get it out, I do not reinstall it as it is not really needed.

 

[ciliaris12]

If you are going to remove the upper cowling (where the mirror is attached), there is a bolt 'hidden' inside up near the head light.
It is a pain to get to (10MM IIRC) but if you don't you will crack the fairing.
Once I get it out, I do not reinstall it as it is not really needed.

thank you phil
seems no need to remove upper cowl.

procedure to be
POCKET
lower cowl
top shelter
middle cowl
i hope it's enough to replace the FAN SW

i'll keep in mind the hidden bolt if i need to remove upper cowl

 

[kiltman]

To what extent did you take off the Tupperware on the right side to examine the hose going from the filler neck to the overflow tank? From my experience, one had to remove the shelter, and the right pocket fairing to truly inspect that hose properly. I know you mentioned that you had looked at the hose and found no defects, but no mention of removing the Tupperware to determine that conclusion.
My other question which you may have answered but I missed, how long have you owned the bike?

 

[ciliaris12]

To what extent did you take off the Tupperware on the right side to examine the hose going from the filler neck to the overflow tank? From my experience, one had to remove the shelter, and the right pocket fairing to truly inspect that hose properly. I know you mentioned that you had looked at the hose and found no defects, but no mention of removing the Tupperware to determine that conclusion.
My other question which you may have answered but I missed, how long have you owned the bike?

hi kiltman
actually i really don't want to remove any COWL in winter. it's terrifying for me, i don't want to crack my old COWLs.
I know it's not good attitude to maintain my old ST1100, but i'm little bit tired painting my another YAMAHA bike, it is extremely exhausting for me.

Yes, when i exchanged my thermostat in this August, i checked overflow hose line, and found no problem.
in my phenomenon, i think FAN SW have problem, overflowing during riding is kind of abnormal situation i think.
if problem not solved even if i exchange FAN SW, then i will remove right side and visually check the hoses.
thank you for your advice but temporary let me focus on FAN SW.


And my ST1100 was produced at 2000 and I have owned it for more than around 15 years. driving mileage is just only 30,000km.
my maintenance and repair experience is not so much, no major trouble happened.
I recently wish to keep ST1100 riding until I retire my work.

 

[red one]

I also own a 2000 ST1100. You stated from a previous post that it does not leak at high temp from the reserve tank? So where is it leaking / overflowing from? It sounds like your fan switch is acting normal as mine won't come on until it is way pass half way. I'd still check the hoses for crud and thermostat housing. I will have to do some checking on mine too because it got down to -7 below zero and I noticed antifreeze leakage not much on my garage floor. The consensus repair for this is the hoses, seals, and water outlets under the carbs. I been saying I'm going to get to it for the last 10 years it's been leaking in the winter. Anyway good luck and don't give up on her for she's a fine machine and although old deserves a second chance

 

[Andrew Shadow]

I have had two ST1100's. It has been a long time so I may be misremembering, but I agree with dwalby that the photo that you show of your temperature gauge in post 31 is not hot enough to activate the fan.

As long as the engine temperature stays out of the red you are not in the danger zone. You might consider letting it get at least a little hotter to confirm fan operation to make sure that you are not chasing ghosts.

 

[ciliaris12]

I also own a 2000 ST1100. You stated from a previous post that it does not leak at high temp from the reserve tank? So where is it leaking / overflowing from? It sounds like your fan switch is acting normal as mine won't come on until it is way pass half way. I'd still check the hoses for crud and thermostat housing. I will have to do some checking on mine too because it got down to -7 below zero and I noticed antifreeze leakage not much on my garage floor. The consensus repair for this is the hoses, seals, and water outlets under the carbs. I been saying I'm going to get to it for the last 10 years it's been leaking in the winter. Anyway good luck and don't give up on her for she's a fine machine and although old deserves a second chance

hi red one
LLC leaked from top CAP of RESERVER TANK i think because the leakage amount was too much. no other leakage found from any other hoses.
FAN SW

I have had two ST1100's. It has been a long time so I may be misremembering, but I agree with dwalby that the photo that you show of your temperature gauge in post 31 is not hot enough to activate the fan.

As long as the engine temperature stays out of the red you are not in the danger zone. You might consider letting it get at least a little hotter to confirm fan operation to make sure that you are not chasing ghosts.

hi Andrew
as i posted previously the photo was taken a little bit later than overflow happened
so the indicator was much more higher when overflow happened.

 

[ciliaris12]

finally FAN was fixed anyway. FAN worked correctly at around 98℃ approx.
removed fan switch did not work while the water(i used edible oil) temperature higher than 110℃
so 1st step was finished.

 

[ciliaris12]

finally FAN was fixed anyway. FAN worked correctly at around 98℃ approx.
removed fan switch did not work while the water(i used edible oil) temperature higher than 110℃
so 1st step was finished.

FAN rotated at this timing

 

[red one]

hi red one
LLC leaked from top CAP of RESERVER TANK i think because the leakage amount was too much. no other leakage found from any other hoses.
FAN SW
hi Andrew
as i posted previously the photo was taken a little bit later than overflow happened
so the indicator was much more higher when overflow happened.

Should not be coming out of reservoir cap should be the reservoir overflow hose. It has to be something you are overlooking. radiator cap overflow hose from thermostat housing air in system thermostat bad. Clogged radiator? blown head gasket? keep at it. Btw Mine was ran briefly into the red zone on temp guage when I was having some cooling issues and my motor did not explode. But remember I said briefly.

 

[ciliaris12]

FAN rotated at this timing

however, LLC leakage again.
almost same timing with FAN SW on.
i thought it was pretty early to overflow since the FAN SW worked correctly temperature at 98℃.
itls not critical problem also the leaked amount also not so huge but i checked the next step.

next step is to ensure FILLER CAP tighly closed, or FILLER CAP's seal surface is clean and no leakage on the overflow path.

this is so much embarrassing but the FILLER CAP was incorrectly assembled. CAP was not surely closed, the rotation angle was a little bit not enough.
i think it was my fault during August's thermostat exchange.
at that time i was confident that i perfectly closed, but now i assume it was not enough.
that's why FILLER CAP opened much earlier timing than designated pressure 1.25kgf/cm2 because the CAP's pressure was a little bit smaller.
then i correctly assembled the CAP, it is quite difficult to close manually, so i used oil filter exchanger.

upper photo shows incorrect CAP closure.
bottom photo is correct one. red line is vertical with vehicle.

fourth photo shows some incorrect foreign residual preventing seal surface work correctly.
fifth photo shows rough sealing surface in CAP, it's time exchange my old CAP, but no dealer working now for new year holidays.

now there's no leakage at all.
it was extremely fantastic experience i fixed problem by myself based on everyone's advice.
thank you all so much supported me.

 

[ciliaris12]

Should not be coming out of reservoir cap should be the reservoir overflow hose. It has to be something you are overlooking. radiator cap overflow hose from thermostat housing air in system thermostat bad. Clogged radiator? blown head gasket? keep at it. Btw Mine was ran briefly into the red zone on temp guage when I was having some cooling issues and my motor did not explode. But remember I said briefly.

yes, some LLC leaked from RESERVER TANK CAP, it's quite easy to observe. however almost all LLC was leaked from LLC drain hose.

 

[red one]

however, LLC leakage again.
almost same timing with FAN SW on.
i thought it was pretty early to overflow since the FAN SW worked correctly temperature at 98℃.
itls not critical problem also the leaked amount also not so huge but i checked the next step.

next step is to ensure FILLER CAP tighly closed, or FILLER CAP's seal surface is clean and no leakage on the overflow path.

this is so much embarrassing but the FILLER CAP was incorrectly assembled. CAP was not surely closed, the rotation angle was a little bit not enough.
i think it was my fault during August's thermostat exchange.
at that time i was confident that i perfectly closed, but now i assume it was not enough.
that's why FILLER CAP opened much earlier timing than designated pressure 1.25kgf/cm2 because the CAP's pressure was a little bit smaller.
then i correctly assembled the CAP, it is quite difficult to close manually, so i used oil filter exchanger.

upper photo shows incorrect CAP closure.
bottom photo is correct one. red line is vertical with vehicle.

fourth photo shows some incorrect foreign residual preventing seal surface work correctly.
fifth photo shows rough sealing surface in CAP, it's time exchange my old CAP, but no dealer working now for new year holidays.

now there's no leakage at all.
it was extremely fantastic experience i fixed problem by myself based on everyone's advice.
thank you all so much supported me.

So that would make sense the hot coolant would flow into the reservoir but since cap loose no vacuum to pull it back into radiator. Still kinda puzzled that no coolant seeped from the loose cap on the thermostat housing. Who knows but glad you are working towards a resolution.

 

[OleBoy]

thank you dwalby
my ST1100 is EUR model, no Japanese domestic model produced.
I also think the CONNECTOR color is strange compared with mannual.

LLC leaked from RESERVER TANK upper CAP. i thought root cause is MOTOR FAN not work. but as you said, too low LLC level might be ROOT CAUSE of FAN not work. I'll check again after filling LLC full.
seems there's no HOSE cracks. though i've not checked but leakage obviously from RESERVER TANK cap.
Re-filled LLC successfully returned to RAD , seems overflow and return tube has no crack.
I understand I need to cool-down engine and let LLC return for several times to re-fill required LLC level. I'll try it, thank you.

 

[OleBoy]

I put a switch in for fan and just ground fan wire to earth works great !