Weird water hose in GL1100.

[vladimirch]

Hi all,

I have a question about the GL1100 cooling system.
My daughter bought a GL1100 Interstate 1981 and while inspecting the motorcycle, I found a strange hose that connects the thermostat area and the water pump. This is the physical bypass of the coolant cooler. You can see the details in the photos.
Have someone of you ever seen anything like this? Can this hose have any practical meaning? I have the feeling that this is practically nonsense, which greatly limits the effectiveness of the coolant cooler. I am concerned that the engine may overheat. I think I'm going to throw the hose away. I will replace the thermostat holder and the water pump lid. Do you have any other idea why someone did this?

The end of the hose connected to the temostat.

The end of the hose connected to the water pump.

The end of the hose connected to the water pump.

Schematic image.

With best regards
Vladimirch
GL1500

[Rambozo]

Lots of engines have a small bypass hose across the thermostat. Typically to help purge air and keep some coolant flow even when the thermostat is closed. This gets rid of hot spots and makes the motor heat up more evenly. Some have a bypass passage cast into the thermostat housing instead of a hose, while others just have a hole in the thermostat. They all do the same job.

[sjk4]

I'm a little late on this one. Just browsing some posts.

I have an '83 1100i and there is no hose like that. From the photos it looks like a DIY modification. If you use the correct thermostat it has a small hole at the top that lets air bleed. Fill the cooling system slowly to give the air a chance to bleed as you fill it and you should have no problems.