91 ST1100 coolant hose change tips???

[number9]

Tom, it sounds like you need to tear the bike back down, drain the coolant a bit so you can remove the T-stat housing and be SURE the T-stat is seated and sealed properly and also clean the knecks off good with a wire brush to get them to seal the best they can.

You may need to use some heat (heat gun) and lube (vasoline) on the hoses to get them on the T-stat housing. I had a time with mine getting them fully seated.

This is not a job you can rush or do less than 100%. You certainly don't want a coolant system failure (leak) in the middle of the desert somewhere in June because of trying to cut a few corners.

 

[TomInOregon]

The thermostat housing is good now. The O-ring wasn't seated properly. Now I just have a leak on the lower hose going onto the T-stat housing from the block. I have tried 5 different hose clamps, cleaned the neck of the T-stat housing and tried combinations of hose clamps, but coolant keeps leaking between the hose and the neck. I have about run out of (constructive) ideas.

Tom

 

[number9]

I wonder if the hoses your sourced from the parts store are a tad larger ID than the Honda hoses?

 

[TomInOregon]

That's certainly a possibility. The funny thing is that they aren't leaking at the engine and the top hose doesn't leak. Maybe a variance in the lower T-stat housing neck combined with slightly ID hose?

Tom

 

[number9]

That hose kneck may have a pinhole in it from simple corrosion or purosity in the casting. It could have a hairline crack as well. But it may actually be a hose fittment issue. Hard to say without actually seeing how it is leaking.

Only way I can think of trying to see what is happening is not quick and easy. You could position the hose as close to the end of the kneck as you can get it and still get a clamp on it above the raised ring. Then put the carbs on and hook enough stuff up needed to start the bike and let it run and get up to temp and see if the area is leaking. If it is a pinhole or crack you may see it on the kneck part that would be exposed and not covered by the hose. Then, move the hose up about 1/2 inch and do it again, and repeat until you have the hose all the way seated at the top of the kneck. If the leak is present during all this and the way it leaks is the same I'd say it could be hose fittment. If the leak changes relative to hose position, you very well could have a crack or pinhole in the kneck, of very bad corrosion.

The thing is, this area of the bike is covered up and very hard to see when the bike is put together. You need to KNOW the leak is fixed when you button everything back up. Otherwise you could be doing it all over the next week.

 

[TomInOregon]

I managed to get it fixed. I put RTV on the neck and then put the hose on over that. Between the RTV and several heating/cooling cycles, it stopped the leak. I checked it good by riding down to Fortuna Ca. for the ST.N WCRM3 meet. ~1,300 miles and the leak hasn't shown back up yet. Thanks for the help.

Tom