Coming from the square hole in the waterpump cover, I was just in the V again the other day, did not see any hoses leaking, but it's definitely apparent that the coolant is coming out of the square hole. Dang biggest problem with this ST, cant run the engine to watch for leaks, because you need the throttle bodies out to see the hoses. Can someone explain exactly whats behind the cover? The diagram really wasn't much help. Ordinarily I'd assume the cover gasket was leaking, but I understand that's not always the case.
Coolant leaking, again
- Thread starter Ozzie
- Start date
I been chasing that same leak for two years now. Ive replaced the water pump cover oring gasket like three times now. Ive been reading on here about the upper hoses leaking but have not been able to see it. I assumed if that was the case that water would be running over the engine V not a specifically designed drain hole that empties out behind the water pump cover making it look like a wpc gasket leak. I went back to 2014 on the leaks post and found a picture that showed the drain path and boy did I feel stupid Also showed two hose clamps on the rear side of the throttle body that I apparently missed. Looks like I have more work to do.
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Blue STar, my '04 ST13, began to seep coolant on cold starts and stops, a couple of seasons back. Over the winter,, I tightened all 8 hose clamps on the engine side coolant system, and checked all those toward the rad. It was not easy to access all the rear-most. However,, more than a full season later,, still no leaks. I did not change the old hoses, or the clamps that were on there. The best possible job would replace all those items, as well as properly preparing and sealing the joinings. I will do that next time around. But for now,,, a bunch of tightening has proven effective,, Cat'
Dave.David
Rider
Can you post that drain path picture for us please?
This is from post made by Byron on June 2013. Any liquid from leaky hoses on top will drain from this hole. My assumption was the leak would run over the edge of the engine V. But after seeing this photo and looking at engine pictures on ebay I now understand the reason for this weep hole. If it weren't there the engine V would fill up and flood the alternator. As I stated in a previous post. I always assumed the leak was coming from the water pump cover gasket.
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Last fall I had a small leak, pulled the radiator and saw a v. small drop of anti freeze on the bottom of the big hose where it joins the right side of the t-stat housing. Tightened the clamp a bit and that was it. However, I also saw corrosion on the bottom of the stat housing so this winter I pulled it apart again, changed the stat, and two big hoses from radiator input and output and used breeze clamps where i could. I'm planning on going back in there in two years to replace every sweet little hose and clamp from the front, if I can, if that fails, then I'll pull the throttle bodkins.
Seems to me years ago i watched an auto mechanic spread some kind of sealant on the spigot of a radiator before he put the hose and clamp on. Wonder why that isn't done today - especially on a bike like the 1300 with its known propensity to weep aunt freeze. If cars can be assembled w/o coolant leaks, why not mc's?
Seems to me years ago i watched an auto mechanic spread some kind of sealant on the spigot of a radiator before he put the hose and clamp on. Wonder why that isn't done today - especially on a bike like the 1300 with its known propensity to weep aunt freeze. If cars can be assembled w/o coolant leaks, why not mc's?
I too had a cold start leak. The pic of Rocket helps me see the path of my leak. The top hose would leak, follow the drain hole circled, then follow the crease along the waterpump cover, exiting at the bottom. Looked just like it was coming from the waterpump weep hole. I struggled at accessing the top hoses from above and added a quarter turn on one of the clamps. Ended my leak 
I went all out and removed the throttle body and all the water hose connections on top. Inspected cleaned all and reassembled. It was about a 6 hour job. One thing I noticed is the throttle body clamps were all loose. Not sure if someone had been in there before me or the clamps worked their way loose like the water hose clamps. Wishing now I would have taken more pictures. It's all back together now so if all is dry after 3 to 4 cold starts then I will call it a total success. I could not get the throttle cable bracket off because the Phillips head screws were so tight. I removed the front frame from the throttle body. The service manual said DONT DO IT. I don't know why. It fits together with enough precision. It now Idles and seems to run a little smoother than before. Im assuming the loose throttle body clamps being tightened back had something to do with that.I too had a cold start leak. The pic of Rocket helps me see the path of my leak. The top hose would leak, follow the drain hole circled, then follow the crease along the waterpump cover, exiting at the bottom. Looked just like it was coming from the waterpump weep hole. I struggled at accessing the top hoses from above and added a quarter turn on one of the clamps. Ended my leak
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We own aging bikes, so we are going to see little problems that are not seen on new ones.
I'm not going to address simple loose hose clamp conditions.
Water on the hose side of the clamps will, over time, seep all or most of the way up to the clamp and will eventually cause corrosion (gray fuzz) to form, which may also eventually creep underneath the clamped area and result in a small drip. Cold runs of just a few minutes, and the moisture can be seen. On longer rides where everything heats up, these little drips will evaporate away leaving no moisture in evidence...but they will cause corrosion to grow around the visible end of the hose, pipe area. Once the corrosion has reached a critical point, you will find evidence of a leak...little drips or streaks...but the leak will have halted and evidence at the source will have evaporated away. So.....unless you are able to physically see the drips in progress, you will be in for a frustrating time trying to locate one of these small leaks. Most of the problematic little drips will be from under the carbs or throttle bodies, depending on your ST, because the connections are not easily visible. The rest can be observed with the removal of a few plastic panels.
I first noticed this when I refurbished my newly purchased ST1100 just two years back. It was quite evident at the thermostat housing connections, so I examined each connection as I replaced the hoses. All had a band of corrosion around the circumference of the metallic connection. I bead blasted that away and inspected for damage under the relatively soft corrosion. Several had deep pits that would never again seal properly against leaks so those got replaced with new, along with all the hose clamps. The serviceable parts were repainted and reinstalled. After two years, no evidence of drips or corrosion.
My 2006 ST1300 has a slow drip, two or three drops on the garage floor every night. NO obvious source. So I have ordered a complete set of water hoses, except for the bulk items and I will go through the whole exercise on my six month old new acquisition.
It's a frustrating condition, but fixing all potential leak locations at once is far better than dropping all the coolant some 100 miles from the nearest aid.
I'm not going to address simple loose hose clamp conditions.
Water on the hose side of the clamps will, over time, seep all or most of the way up to the clamp and will eventually cause corrosion (gray fuzz) to form, which may also eventually creep underneath the clamped area and result in a small drip. Cold runs of just a few minutes, and the moisture can be seen. On longer rides where everything heats up, these little drips will evaporate away leaving no moisture in evidence...but they will cause corrosion to grow around the visible end of the hose, pipe area. Once the corrosion has reached a critical point, you will find evidence of a leak...little drips or streaks...but the leak will have halted and evidence at the source will have evaporated away. So.....unless you are able to physically see the drips in progress, you will be in for a frustrating time trying to locate one of these small leaks. Most of the problematic little drips will be from under the carbs or throttle bodies, depending on your ST, because the connections are not easily visible. The rest can be observed with the removal of a few plastic panels.
I first noticed this when I refurbished my newly purchased ST1100 just two years back. It was quite evident at the thermostat housing connections, so I examined each connection as I replaced the hoses. All had a band of corrosion around the circumference of the metallic connection. I bead blasted that away and inspected for damage under the relatively soft corrosion. Several had deep pits that would never again seal properly against leaks so those got replaced with new, along with all the hose clamps. The serviceable parts were repainted and reinstalled. After two years, no evidence of drips or corrosion.
My 2006 ST1300 has a slow drip, two or three drops on the garage floor every night. NO obvious source. So I have ordered a complete set of water hoses, except for the bulk items and I will go through the whole exercise on my six month old new acquisition.
It's a frustrating condition, but fixing all potential leak locations at once is far better than dropping all the coolant some 100 miles from the nearest aid.
I'm on your side hoping for dry morning starts. Also agree: my idle improved after snugging up several throttle body connections.