ST1300 coolant leak

[ST1]

I have a ST 1300 A6 i noticed some coolant staining on the right hand side engine block.
i have removed the side cover to inspect.

I am starting the bike and getting it up to operating temperature to try and see where the leak is.

 

[GhenghisKen]

What about that crack in photo number#2 just to the left of that bolt?

 

[ST1]

I ran the bike for 15 minutes the fans came on as normal and stayed at three bars on the temperature gauge.
The round hole above the square one was a bit wet, i place a cotton bud inside and there are green marks.

The big bolt is a mount for the radiator.

 

[gordow88]

What about that crack in photo number#2 just to the left of that bolt?

good eye.

 

[SupraSabre]

This is what a water pump leak looks like:



And from the Square hole, coolant leaking from the valley or thermostat cover.

 

[SMSW]

What about that crack in photo number#2 just to the left of that bolt?

Looks to me like a casting flaw, not necessarily a crack.

 

[vstrom.zrxdude]

Water pump cover o ring groove corodes, cleaned,resealed my cover only with old o ring silicone sealer ,holds coolant good now,184500 mi on mine now never replaced wp mechanical seal

 

[dduelin]

Every ST1300 on the planet weep, seeps, or leaks coolant from umpteen hose connections, most of which are concealed under the rubber heat mat in the vee of the cylinder banks and/or behind the radiator. Once seen in the light of day it is a simple job to stop or reduce the leaks by slightly snugging up the OEM hose clamps or replacing them. The O-ring that seals the thermostat housing is also probably leaking. It’s not difficult to set things to right. I’m out riding today but when I get home, I will attach a PDF file with a tutorial on how to remove the radiator and access the thermostat housing if you haven’t already done that.

 

[eyrepb]

Looks to me like a casting flaw, not necessarily a crack.

I will guess a shadow of the rough edge from the light angle

 

[RVtraveler48]

My 2009 ST1300A has had a small coolant leak for ages, but it was not much and easy to keep up with. Realized I'd never had the radiator flushed - $400 later it's leaking much worse. 1/2 pint in 100 miles of local driving. 1) could flushing the coolant (94,000 miles 1st flush) have worsened the leak? 2) Is putting radiator stop leak in via the reservoir (only easy access) an ok idea? A good idea? A terrible idea? When it was apart for the flush the mechanic said there was a leak but he couldn't tell from where. Water pump cover looks like a brutal job. I'm interested in opinions about the stop leak idea. Thanks!

 

[Andrew Shadow]

He had to open the system somewhere to be able to flush it. Maybe he left a hose clamp loose somewhere.

ST1300's are known to leak at the hose connections in the vee and to the thermostat. Snug them up.

Stop leak is a bad idea in my opinion as it often blocks up things that it shouldn't. Better to find and fix the leak.

 

[Al st1100]

He had to open the system somewhere to be able to flush it. Maybe he left a hose clamp loose somewhere.

ST1300's are known to leak at the hose connections in the vee and to the thermostat. Snug them up.

Stop leak is a bad idea in my opinion as it often blocks up things that it shouldn't. Better to find and fix the leak.

I'll bet the hose connection is all corroded and driving blows the coolant towards the back showing up on the block. Notice how swollen the hose is at each side of the clamp.The pump may be leaking too.

 

[Buckeyechris]

@ST1

The lower hole is likely evidence not a leaking water pump but a coolant leak under the throttle body. Here a thread that discusses the weep holes: https://www.st-owners.com/forums/threads/st1300-water-pump-weep-holes.166819/.

On my '05, the O-rings, shown as part #24 on the parts diagram below, had nearly totally disintegrated. Coolant was leaking from the top of both cylinder heads, down a channel under the front cover, and exiting the lower hole on the cover.


If the leak is coming from the upper hole, then it might be a coolant pump leak. If I were in your shoes, I'd remove the airbox and pull back some of the rubber matting near the front of the bike to look for coolant leaks. Although I've not done it, pulling the front cover off and replacing the pump is not for the faint of heart.

Chris

I have a ST 1300 A6 i noticed some coolant staining on the right hand side engine block.
i have removed the side cover to inspect.

I am starting the bike and getting it up to operating temperature to try and see where the leak is.