Coolant leakage.

Joined
Jul 5, 2017
Messages
81
Location
DFW
Bike
ST1300
Bike is an 07 ST1300 with 39,500. Bought in 7/17 with 38,000.

This past Monday I was out for a ride, temp here in DFW was near 80F. Rode for a couple of hours, in town, several stops then get home, park the bike and shut it off. After dismounting and removing gear I notice a puddle of coolant below the bike about a cups worth. Freak out time, wipe up mess, turn bike on, fans run temp bars at mid level. Wednesday, I pull the plastic, no evidence of any leaks. I run the bike two different times, first 10 minutes then 20 minutes plus. No leaks and the temperature does not go over mid point. The coolant bottle the entire time was about 3/4" over the full line but did not move. Take if for a nekkid ride about 90 minutes, still same results. I checked the radiator and it has plenty of fluid.

At this point I'm puzzled, a little apprehensive about putting plastic back on only to have it mark it's territory again. The only thing I can think of to do is check the thermostat.

Also while I have all the plastic off, is there any maintenance that I should be doing. Oil & filter were last changed 2,000mil/2years ago. Spark plugs & air filter were changed at 20,000. I plan on inspecting the air filter, plugs and checking the oil. Am I missing anything?
 
Joined
Jun 3, 2009
Messages
248
Location
Surrey, BC, Canada
Bike
2008 Goldwing GL1800
I have a 2007 too. I had major coolent leak August this year. See picture. Tried to fix it myself, too technical, took it to my favourite shop, replaced all hoses and clamps up in the valley, new coolant and new thermostate, rebuilt water pump.
Your leak could come from the radiator cap. There should be an overflow tube from the cap neck to the plastic reservoir. It may be disconnected.
For a 10 year ST, if the coolant, radiator cap, and thermostate are original, I would change them.
The rear differential oil should be changed as well. You can do that without pulling the panels.
I can't think of anything else for now. The ST is a very reliable bike.
 

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SupraSabre

48 Years of SoCal Lane Splitting/Commuting-Retired
Site Supporter
Joined
Nov 20, 2005
Messages
9,497
Location
Cedar City, Utah
Bike
12/04 ST 1300s
2024 Miles
000145
STOC #
5901
Check the small hoses that are behind the radiator cap. There is a three way connector that is known to crack. It connects three hoses, with two different sizes. Also check your clamps. you can do that by removing the airbox under the gas tank and pulling back the rubber heat dam.

Even though the oil only has 2,000 miles on it, I would probably replace it since it's two years old.

If you have the maintenance records of the bike, check them out to make sure brakes and clutch have been bled, and other maintenance has been done.

If you don't have a maintenance record, you need to change out all fluids including the radiator/coolant!

Good luck!
 
Last edited:
Joined
Mar 13, 2016
Messages
24
Location
Ardmore Ok
Bike
2007 Honda ST1300
Come and go coolant leaks aren't unheard of on the ST1300. There's about 2,000 posts on the subject here:

https://www.st-owners.com/forums/forumdisplay.php?457-ST1300-Leaks
My 2007 is leaking too for the second time. I found the problem to be the oring gasket on the water pump cover. I replaced it and applied some silicone sealer just to see what would happen. Stayed fixed until I started the bike up on a 50 degree morning and it started leaking again. It may not have been a good idea to apply the silicone sealer being it was not assembled with it at the factory so next time I will leave it off. Im not sure why the gasket started leaking to begin with. My only guess is when the engine starts to heat then the aluminum parts are expanding causing the oring to roll and tweak. ?? Duno. I have another new gasket now. Just need to get it done. Just wondering if I should apply a small amout of grease or silicone oil to the flat surface the oring gasket sits against. Maybe that will let it slide a litle to keep it from rolling tweaking.

Mark
 

SupraSabre

48 Years of SoCal Lane Splitting/Commuting-Retired
Site Supporter
Joined
Nov 20, 2005
Messages
9,497
Location
Cedar City, Utah
Bike
12/04 ST 1300s
2024 Miles
000145
STOC #
5901
My 2007 is leaking too for the second time. I found the problem to be the oring gasket on the water pump cover. I replaced it and applied some silicone sealer just to see what would happen. Stayed fixed until I started the bike up on a 50 degree morning and it started leaking again. It may not have been a good idea to apply the silicone sealer being it was not assembled with it at the factory so next time I will leave it off. Im not sure why the gasket started leaking to begin with. My only guess is when the engine starts to heat then the aluminum parts are expanding causing the oring to roll and tweak. ?? Duno. I have another new gasket now. Just need to get it done. Just wondering if I should apply a small amout of grease or silicone oil to the flat surface the oring gasket sits against. Maybe that will let it slide a litle to keep it from rolling tweaking.

Mark
When you put that cover on, make sure you have the correct torque values! If you just "tighten it up", it will leak on you!
 
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Chef Jim
Joined
Jul 5, 2017
Messages
81
Location
DFW
Bike
ST1300
Try as I might I could not get it to leak again. I think the problem was the over flow container was over filled. I emptied some coolant out and all seems to be good. Hoses and clamps inspected, all in good shape and look to have been replaced.

IMG_1521.jpgIMG_1504.jpg
 

Mellow

Joe
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Joined
Dec 1, 2004
Messages
18,819
Age
60
Bike
'21 BMW R1250RT
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000540
Excellent, always nice when it's an easy fix.
 
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Chef Jim
Joined
Jul 5, 2017
Messages
81
Location
DFW
Bike
ST1300
Yes, sometimes you get lucky. Now if it would stop raining.
 
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