Thermostat o-ring leak

[Raia]

With 30,000 miles the thermostat o- ring is leaking,I’ve been smelling it for a while and had to add some antifreeze to the overflow bottle, but no complaints, other than maintenance. This has been the first repair.

 

[SMSW]

You did not say what year bike you have. While you are in there, consider pulling the big hoses off the front of the thermostat housing. Look for corrosion on the metal.

 

[Raia]

2017, I had pulled the hoses off of housing ,was nice and clean under the hoses and they were tight.

 

[Rob20111]

With 30,000 miles the thermostat o- ring is leaking,I’ve been smelling it for a while and had to add some antifreeze to the overflow bottle, but no complaints, other than maintenance. This has been the first repair.

Mine (ST1300) was leaking at only 12,000 miles, but the bike was 18 years old.
When I got the housing opened I noticed the thermostat was stuck about 1/3 - 1/2 open.
Tested it in a pot of boiling water on the stove, didn’t move, hot or cold. Replaced it with a new one.
Removed all the reachable hose ends and cleaned the metal connections, and tightened all clamps.
Cleaned the ground wire connection next to the T-stat housing which was slightly corroded.
Easy job to do, just drain coolant and remove radiator and frame cross member.
Be careful not to scratch your front wheel fender.

 

[Al Gully]

One of the thermostat bolts siezed into the base of the housing and snapped a chunk of the housing off.
I replaced the housing base, housing cover, thermostat, 2 bolts and O-Ring.
Reused the hose clamps.
No leaks