ST1100 LLC leakage. how to separate FAN HARNESS

[ciliaris12]

Hi
could anyone tell me how to separate this WIRE CONNECTOR from SW??

Yesterday my ST1100 had LLC leakage
during short touring. FAN-MOTOR didn't work at all.
I assume FAN MOTOR or its' fuse had some problem.

So i tried to separate the wire , then i wanted to connect to body for body-earthing. Because if SW has failure, direct earthing will make the MOTOR work.
But it's quite difficult to separate.

please anybody tell me how to do it.

 

[Uncle Phil]

Normally you just wiggle the connector loose - yours looks like it is cracked.
The top 'cap' pulls loose from the switch.
(I just happened to have a radiator on the bench from my recent engine swap) -

 

[ciliaris12]

Hi Phil
thank you so much advising.
I'll try wiggling it.

 

[Uncle Phil]

You may have to get a small screwdriver and gently pry it off the sensor.

 

[ciliaris12]

I'll keep some related documents for anyone's reference,
I'm very sorry if it's not suitable to post them

Hi
could anyone tell me how to separate this WIRE CONNECTOR from SW??

Yesterday my ST1100 had LLC leakage
during short touring. FAN-MOTOR didn't work at all.
I assume FAN MOTOR or its' fuse had some problem.

So i tried to separate the wire , then i wanted to connect to body for body-earthing. Because if SW has failure, direct earthing will make the MOTOR work.
But it's quite difficult to separate.

please anybody tell me how to do it.




modify; 20th Dec.
add some documents for anybody's reference.
I'm very sorry if they're not suitable to post.

 

[dwalby]

your connector doesn't look familiar to me, the one in Phil's photo looks like mine. Not sure if that's a difference between US and Japan models, or if someone has replaced the original connector.

Don't try to force it too much, you may end up breaking the connector, and it may not be your primary problem.

That coolant leak in your picture looks like it could be one of the hoses under the carbs leaking, or it could be the overflow tank being overfilled. Take a look under the right body panel at the overflow tank and see if its full, if so, then look at the overflow hose attached to the radiator at the cap. They tend to crack over time and cause coolant to flow into the overflow tank, but not return after the engine cools down because the crack prevents a vacuum from being created to suck the coolant back from the overflow tank into the radiator. This is a very common failure with the simple solution to just cut off the part with the crack (its usually very close to the rad cap where the tube makes a sharp bend towards the rear of the bike).

As the coolant level drops one of the secondary symptoms is the fan stops working because the coolant level drops below the level needed to activate the switch. So rather than try to troubleshoot the switch, look first at the overflow tank and reply back.

 

[Oldbikefixr]

Seems the single most troublesome hose is the one that runs from the thermostat housing back to the reservoir. This was the first thing I fixed when I bought mine a while back. Had to replace the thermostat housing as well as the hose connections were badly corroded. Doesn't show at this angle but the ridge at the end of the overflow connection was really bad on the other side, I didn't think it would ever seal properly. I bead blasted the corrosion away and spray painted it so the depth of the corrosion could be seen.

your connector doesn't look familiar to me, the one in Phil's photo looks like mine. Not sure if that's a difference between US and Japan models, or if someone has replaced the original connector.

Don't try to force it too much, you may end up breaking the connector, and it may not be your primary problem.

That coolant leak in your picture looks like it could be one of the hoses under the carbs leaking, or it could be the overflow tank being overfilled. Take a look under the right body panel at the overflow tank and see if its full, if so, then look at the overflow hose attached to the radiator at the cap. They tend to crack over time and cause coolant to flow into the overflow tank, but not return after the engine cools down because the crack prevents a vacuum from being created to suck the coolant back from the overflow tank into the radiator. This is a very common failure with the simple solution to just cut off the part with the crack (its usually very close to the rad cap where the tube makes a sharp bend towards the rear of the bike).

As the coolant level drops one of the secondary symptoms is the fan stops working because the coolant level drops below the level needed to activate the switch. So rather than try to troubleshoot the switch, look first at the overflow tank and reply back.

 

[ciliaris12]

your connector doesn't look familiar to me, the one in Phil's photo looks like mine. Not sure if that's a difference between US and Japan models, or if someone has replaced the original connector.

Don't try to force it too much, you may end up breaking the connector, and it may not be your primary problem.

That coolant leak in your picture looks like it could be one of the hoses under the carbs leaking, or it could be the overflow tank being overfilled. Take a look under the right body panel at the overflow tank and see if its full, if so, then look at the overflow hose attached to the radiator at the cap. They tend to crack over time and cause coolant to flow into the overflow tank, but not return after the engine cools down because the crack prevents a vacuum from being created to suck the coolant back from the overflow tank into the radiator. This is a very common failure with the simple solution to just cut off the part with the crack (its usually very close to the rad cap where the tube makes a sharp bend towards the rear of the bike).

As the coolant level drops one of the secondary symptoms is the fan stops working because the coolant level drops below the level needed to activate the switch. So rather than try to troubleshoot the switch, look first at the overflow tank and reply back.

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.

 

[ciliaris12]

Seems the single most troublesome hose is the one that runs from the thermostat housing back to the reservoir. This was the first thing I fixed when I bought mine a while back. Had to replace the thermostat housing as well as the hose connections were badly corroded. Doesn't show at this angle but the ridge at the end of the overflow connection was really bad on the other side, I didn't think it would ever seal properly. I bead blasted the corrosion away and spray painted it so the depth of the corrosion could be seen.

Hi Oldbikefixr
oh, it's really really terrible corrosion
Very surprising the point is inside of HOSE.
I will check any corrosion in HOSE line more precisely.
Fortunately my filler neck had no problem at all when I exchanged my thermostat in August this year.

 

[dwalby]

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.

OK, good info here.

First question is what is the level of your overflow/reserve tank after the engine cools down? If its too high to begin with, then the additional coolant pumped in while the engine is hot may be enough to overflow it. Make sure its at the line level on the tank when cold.

Then if that checks out OK, the next step is to strip the bodywork to get access to the radiator cap. Remove the cap and fill the radiator until the level is at the bottom of the neck. Run it for 30 seconds or so to pump the coolant around and purge any air, then put the cap back on (refill if a lot of air is purged and level drops). Run the bike up to temp and if the fan doesn't come on, then you start troubleshooting the fan and the thermo switch.

BTW, I know you're referring to the coolant as "LLC", but I've never heard that term before, what does it mean?

 

[ciliaris12]

Seems the single most troublesome hose is the one that runs from the thermostat housing back to the reservoir. This was the first thing I fixed when I bought mine a while back. Had to replace the thermostat housing as well as the hose connections were badly corroded. Doesn't show at this angle but the ridge at the end of the overflow connection was really bad on the other side, I didn't think it would ever seal properly. I bead blasted the corrosion away and spray painted it so the depth of the corrosion could be seen.

OK, good info here.

First question is what is the level of your overflow/reserve tank after the engine cools down? If its too high to begin with, then the additional coolant pumped in while the engine is hot may be enough to overflow it. Make sure its at the line level on the tank when cold.

Then if that checks out OK, the next step is to strip the bodywork to get access to the radiator cap. Remove the cap and fill the radiator until the level is at the bottom of the neck. Run it for 30 seconds or so to pump the coolant around and purge any air, then put the cap back on (refill if a lot of air is purged and level drops). Run the bike up to temp and if the fan doesn't come on, then you start troubleshooting the fan and the thermo switch.

BTW, I know you're referring to the coolant as "LLC", but I've never heard that term before, what does it mean?

ok, I'll check the level.
in my memory, it's between highest and lowest indicator. i think it's normal level.
in my understanding, the LLC level in filler neck was high enough when i exchanged the thermostat at this August. i didn't drained LLC at that time. so no concern mixed air caused some failure in the circuit.
i can understand the LLC amount was enough because filler neck position is highest in ST1100 cooling circuit.
basically it's impossible for SW to oppose over the LLC level.

sorry LLC means long life coolant. i am Nissan cooling system engineer in Japan. we call it as LLC.
i think both are same for car or motorcycle.
sorry late introducing myself. i can imagine the structure by maintenance manual but difficult to disassemble or fix.
anyway thank you for your advice

 

[kiltman]

i think both are same for car or motorcycle.

Not necessarily, however as you are a coolant engineer, I’m assuming that you know the coolant has to be friendly to the aluminum components of the engine, especially the water pump. (I use the Honda coolant)
The other members here are giving excellent troubleshooting advice. Good luck

 

[ciliaris12]

Not necessarily, however as you are a coolant engineer, I’m assuming that you know the coolant has to be friendly to the aluminum components of the engine, especially the water pump. (I use the Honda coolant)
The other members here are giving excellent troubleshooting advice. Good luck

thank you kiltman
In Japan we can buy LLC ethylene glycol 90% or more, and anti-rust materials. it's Japanese standard "JIS". LLC is very strictly managed by JIS standard.
and normally we don't add water.
sorry i didn't use Honda genuine LLC but i think LLC composition is same especially in Japan.
for your reference, Japanese JIS do not separate LLC standard for car or motorcycle.

 

[dwalby]

sorry late introducing myself. i can imagine the structure by maintenance manual but difficult to disassemble or fix.
anyway thank you for your advice

The thermal switch is generally reliable, but now that these bikes are entering the 25+ years old phase I guess anything can fail.

Sounds like you think the coolant level is going to check out OK, but its a good idea to make sure before going any further.

Another potential cause of fan failure is corrosion at the electrical ground point on the radiator. The switch closes, but the radiator ground is poor and the fan can't draw enough current to run.

If you can pry that connector off without breaking anything, measure the voltage at the connector, you should have 12 volts (approx.) on that connector with the ignition on. If no voltage then there's something wrong between the ignition switch and the connector.

 

[red one]

thank you kiltman
In Japan we can buy LLC ethylene glycol 90% or more, and anti-rust materials. it's Japanese standard "JIS". LLC is very strictly managed by JIS standard.
and normally we don't add water.
sorry i didn't use Honda genuine LLC but i think LLC composition is same especially in Japan.
for your reference, Japanese JIS do not separate LLC standard for car or motorcycle.

Your Japanese coolant I assume is the same formula that Honda and Toyota uses here in the USA. I'm happy to report I have over 232K miles on my 05 corolla and it still has the same original cooling system components radiator, hoses, water pump, thermostat etc etc. Same deal on my over 82K mile ST1100 oem radiator, water pump, all hoses have not been changed etc for the reservoir tank to thermostat housing hose and the fan switch and thermostat has been changed 1 time. The Asian stuff is pretty good that's why I only use the oem fluids.

 

[ciliaris12]

The thermal switch is generally reliable, but now that these bikes are entering the 25+ years old phase I guess anything can fail.

Sounds like you think the coolant level is going to check out OK, but its a good idea to make sure before going any further.

Another potential cause of fan failure is corrosion at the electrical ground point on the radiator. The switch closes, but the radiator ground is poor and the fan can't draw enough current to run.

If you can pry that connector off without breaking anything, measure the voltage at the connector, you should have 12 volts (approx.) on that connector with the ignition on. If no voltage then there's something wrong between the ignition switch and the connector.

hi dwalby
yes my ST1100 is 20 years old, so i will check every part for sure.
thank you, checking ground point corrosion is necessary.

sorry, to check between which voltage?
originally I am planning to connect the separated CONNECTOR to earth point of SHROUD. Is my trial same with yours?

 

[ciliaris12]

Your Japanese coolant I assume is the same formula that Honda and Toyota uses here in the USA. I'm happy to report I have over 232K miles on my 05 corolla and it still has the same original cooling system components radiator, hoses, water pump, thermostat etc etc. Same deal on my over 82K mile ST1100 oem radiator, water pump, all hoses have not been changed etc for the reservoir tank to thermostat housing hose and the fan switch and thermostat has been changed 1 time. The Asian stuff is pretty good that's why I only use the oem fluids.

yes, Japanese staff normally try to satisfy customer expectations. and sometimes
the attitude tends to be too much, but it's good for us.
I met Mr. Yamanaka last year who developed ST1100. he is so much sincere, cheerful and so jovial. I respect him as a same engineer.

 

[red one]

yes, Japanese staff normally try to satisfy customer expectations. and sometimes
the attitude tends to be too much, but it's good for us.
I met Mr. Yamanaka last year who developed ST1100. he is so much sincere, cheerful and so jovial. I respect him as a same engineer.

Mr Yamanaka designed a masterpiece when he developed the ST1100. The man should be enshrined in the Honda's Hall of fame

 

[dwalby]

sorry, to check between which voltage?
originally I am planning to connect the separated CONNECTOR to earth point of SHROUD. Is my trial same with yours?

yes, we're talking about the same thing.

Now, if for some reason the fan doesn't come on when you ground that connector, that's what I meant by checking the voltage at the connector with the ignition switch on. Put the (+) lead on the connector, and the (-) lead on the battery negative terminal. If you don't have something close to 12v between the connector and ground, then there is a problem in the electrical path to the connector.

The other way the electrical path can fail is if there's corrosion on the ground at the radiator. That will cause a voltage drop which prevents the fan from drawing enough current to run. To test that out put your multimeter in ohms mode and measure the resistance from the radiator ground point (the base of the thermo switch) and the battery negative terminal. That resistance should only be a few tenths of an ohm, something like 0.5-0.7 ohms or so, if its a lot more than that then there's something in the ground path that needs to be cleaned up.

 

[tnbill]

A better test on these would be a 20 watt light bulb as the ohm meter will not test it for load capacity.