Coolant Leak When Cold

Joined
Feb 27, 2012
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central NJ
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2010 Honda ST13
When I start my ST1300, I get few drops of coolant from the overflow tube near the front of the engine. As soon as the bike warms up, the leak stops. It may resume without starting the bike if I take it out of the garage and it's slightly warmer outside.

Is this a clue that the waterpump is leaking?
 

Mellow

Joe
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A slight leaking is normal per the manual... We see this a lot when the temps start getting colder.
 
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It is one of "they all do that " things.
I have never met anyone who has had a ST1300 for any length of time who has not experienced this.
Tons of documentation about this in the forums.

My ST1100s were much worse!
 
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Jan 8, 2011
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Arizona
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2007 Honda ST1300A
I believe the OP said the coolant is coming out of the TUBE, which on his bike is attached to a Zerks fitting (round hole point).
Leaking, is NOT acceptable, Seeping is normal (damp).
If you start the bike and watch the end of the hose, if the drops come out every few seconds, like a heart beat, then you could have a failing waterpump.
However, on such a new bike, I would agree that its probably loose clamps, leaking out the square hole, and running down the side of the hose, appearing that its coming out of the hose.
Clean and dry everything off, and spray some foot powder on the area, then start the bike a watch it, you'll see where its leaking from.
If its the common loose clamps, it could also be leaking along the shelf of the front water pump cover, and exiting the square hole, just spray the entire area and you'll see right away were its leaking.
 

Blrfl

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Leaking coolant may dribble down the front of the engine and along the bottom of the oil pan to about where the overflow tube is. If the leak stops when warm, odds are very good it's the hose clamps.

These threads bode winter like the mouse-eaten FI wiring threads bodes spring. :)

--Mark
 
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When I start my ST1300, I get few drops of coolant from the overflow tube near the front of the engine. As soon as the bike warms up, the leak stops. It may resume without starting the bike if I take it out of the garage and it's slightly warmer outside.

Is this a clue that the waterpump is leaking?
I need help!!! I have a 2009 Honda st1300pa every morning when i start bike i get a puddle of coolant running down from the square hole... can anyone tell me what going on? I’m getting all kinds of different things like water pump seal and etc.
 

Andrew Shadow

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Jan 28, 2012
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Montreal
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Coolant leak from the square hole is not the water pump. It is coolant being drained down from the the vee of the motor. There are quite a few coolant hose clamps in there for the thermostat, SE wax valve, bypass hose, etc. These hose clamps typically are lose and allow coolant loss. Snugging them up will probably stop the leak but they may leak again after many thousands of miles.

This article explains the two weep holes and what each one drains.
ST1300 - Water Pump Weep Holes

This article details the issue of the loose clamps and a permanent resolution. I simply tightened my clamps up and have not had another leak for 80,000 KM, 50,000 miles.
ST1300 - Solving the Coolant Leak Problem... For Good
 
Last edited:
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Cleveland
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Mentioned in that second article are Gates constant tension clamps. @SupraSabre installed Gates heat shrink "clamps" (well, they are more accurately called bands" on his hoses and has not been hosed since. (Sorry, I couldn't resist). :rofl1: I think there is a thread with the sizes and part numbers. IIRC, McMaster Carr sells them as well as other vendors. They are not expensive, and require no fiddling around to make sure there is no iterference with the screw-tightening mechanism in the tight area of the 'V" of the engine. You will have to cut them off to remove the hose, however.
 
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