Coolant Leak right in the middle of my ST1100

I'm with dwalby. If you were careful and installed all the recommended new parts properly, nothing to do but button it up and go. You don't need to put all the plastic back on until you're comfortable there are no leaks.

And just in case, the insulators are secured to the intakes for installation, not the carbs. The ramps help the carbs in, and a bit of silicone paste will make the installation drama-free. Just make sure you're applying pressure like outlined in other posts so you don't damage anything.

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Oh, and you may also want to give yourself a generous amount of length for the vacuum hoses so syncing the carbs is easier. You can always cut them shorter when you button it all up.
 
I took off the 4 hoses and found nothing to suggest leaking. I replaced all the hoses anyway and connected everything back and mounted the radiator. Was filling the radiator to see if and where water may leak from again. Water was pouring out on left side where the water pipe is located. What can I do to check this out?
 
Hello everyone,
I went through more or less the same issues, thankfully I only had to change the hoses, but when reassembling it all I found this problem with the little valve on top of the gas filter, could anyone tell me why this happened and how to fix it.
 

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Romonov said:
Hello everyone,
I went through more or less the same issues, thankfully I only had to change the hoses, but when reassembling it all I found this problem with the little valve on top of the gas filter, could anyone tell me why this happened and how to fix it.
Click to expand...
The diaphragm inside the valve is torn. Rebuild kits are available but most people claim that they are not reliable.
Many ST1100 owners just permanently bypassed it when it started to leak and removed it.
Many others have done the same as a preventative maintenance procedure to avoid having troubles while on the road.

Bypass it and forget about it. The below article details how to do it.
How to do an emergency bypass of the fuel valve
 
Winfried said:
I took off the 4 hoses and found nothing to suggest leaking. I replaced all the hoses anyway and connected everything back and mounted the radiator. Was filling the radiator to see if and where water may leak from again. Water was pouring out on left side where the water pipe is located. What can I do to check this out?
Click to expand...
Did you replace the small bypass hose that goes from the water pipe to the thermostat housing?
 
Andrew Shadow said:
The diaphragm inside the valve is torn. Rebuild kits are available but most people claim that they are not reliable.
Many ST1100 owners just permanently bypassed it when it started to leak and removed it.
Many others have done the same as a preventative maintenance procedure to avoid having troubles while on the road.

Bypass it and forget about it. The below article details how to do it.
How to do an emergency bypass of the fuel valve
Click to expand...
Thanks so very much!
 
Smudgemo said:
Did you replace the small bypass hose that goes from the water pipe to the thermostat housing?
Click to expand...
I changed a thin hose that goes from the front left side of the engine to the thermostat, because it had a crack and leaked.
 
Winfried said:
I took off the 4 hoses and found nothing to suggest leaking. I replaced all the hoses anyway and connected everything back and mounted the radiator. Was filling the radiator to see if and where water may leak from again. Water was pouring out on left side where the water pipe is located. What can I do to check this out?
Click to expand...
did you replace the O-rings on the elbows that the hoses attach to?

Winfried said:
From the parts diagram, is it the number 13 number? And how do you get up to it?
Click to expand...
it was under the mat while you were down in the guts of the job. Its a 5-6mm hose that goes from a nipple on the water pipe over to the T-stat housing.

there's also an O-ring inside the water pipe connection to the housing at the top. Some of us have replaced that O-ring, and some haven't.

It sounds like you'll have to pull the carbs again and look inside to see where the water is leaking from. Or maybe just pull the gas tank to look under the carbs and you might be able to see it from there. The mat may be in your way though, so the carbs may have to come off.
 
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Good luck with the carbs in the way. Rubber ring on the end of the water pipe is mentioned above by dwalby as a potential leak if old.

Bypass.jpg
 
Smudgemo said:
I'm with dwalby. If you were careful and installed all the recommended new parts properly, nothing to do but button it up and go. You don't need to put all the plastic back on until you're comfortable there are no leaks.

And just in case, the insulators are secured to the intakes for installation, not the carbs. The ramps help the carbs in, and a bit of silicone paste will make the installation drama-free. Just make sure you're applying pressure like outlined in other posts so you don't damage anything.

1674326254687.png
Click to expand...
Guys, how important is the rubber mat in the picture? My ST didn’t have when I bought it from a good friend
 
Romonov said:
Guys, how important is the rubber mat in the picture? My ST didn’t have when I bought it from a good friend
Click to expand...
hard to say for sure, its some kind of heat barrier for the carbs but nobody has tried removing it, so you're our guinea pig for this experiment. If the bike runs OK in the heat without it, then you probably don't really need it.
 
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