Coolant Leak right in the middle of my ST1100

Bike is always stored in the garage. I bought the bike 12/31/2015. I do the regular oil changes, flushed the radiator once before. Never took everything apart like this. Looking down on this, it's hard to differentiate what hoses belong to what. Had to tear the top mat just to look underneath. What is the metal thing dead center? The hoses and other connections, elbows, o-rings, do I find those on PartZilla, eBay, Honda dealership's parts dept?
 
Winfried said:
Totally frustrated. I removed the motor mount and isn't helping as I cannot see the head of any screw whatsoever. I feel like I had a totally driveable motorcycle and now I have a total torn apart motorcycle ready to be sold as parts, and all for a radiator hose leak.
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Hang in there! Those on this forum are patient and helpful; especially when you get as far into your bike as you have! And you'll be better for the work you successfully completed and the knowledge you gained in doing so!
 
When loosening - Go easy on those bolts holding the the elbows , they are long , thin (6mm?) and go through a lot of aluminium , which can corrode them over time. Penetrating oil and time and repeat - if in doubt !
 
Winfried said:
What is the metal thing dead center?
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If I’m reading you correctly, that’s the Air Suction Valve (PAIR). I don’t recall… are you using the Honda Service Manual….?

If you really want to identify the current source of the coolant leak, just go to the nearest Auto Zone and borrow their coolant system pressurization kit for free, BTDT. Get the adapter for the ST1100 radiator coolant filler neck (replaces the radiator cap) and pump up the pressure with the little pump through the adapter to 18 PSI. The leak will appear soon after… again, BTDT

Damn, that’s one of the worST/dirtieST “under-carbs” I’ve seen. You ride an older motorcycle that requires ongoing and long-term care. When you reinstall be sure to hook up the carb bowl drain hose to the 4-way drain manifold under the carbs.

John
 
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Okay, I ordered the elbows on PartZilla, the hoses and carb insulators on eBay. On PartZilla, found carb insulators but couldn't tell if they were for my ST1100. But on eBay, they were clearly marked for the ST1100.
 
The complete parts list is in the ST-Riders article. Don’t forget the o-rings for the elbows. The insulators are the same for all years/models.
 
here's a parts list that I used when I did mine, check the numbers against your orders. The bulk hose can be found at an auto parts store rather than ordering it from Honda, its way too much hose, and way too much money from Honda. Its the thin tube that goes from the water pipe to the T-stat housing.

hoses2.jpg
 
After the carbs were removed and the insulators were removed, to get to the hoses to be replaced, the rubber cover was totally torn up. I can't seem to find the replacement for it. Tried searching but don't know what it is called or the part number.
 
I've replaced the 4 hoses. and what they are connected to and I don't see or feel where the coolant leaked from. Putting radiator back so it is just hanging there and about to go about attaching hoses, but don't want to tighten anything down until I identify where it was leaking from.
 
I'm putting the boot insulators on but can't remember how they came th-3338927962.jpgoff. Can't tell right side up and which part points to which direction.
 
Those appear to be upside down. The tab that forms the v goes over the cast ridge of the intake to prevent them from spinning, and the top has a bit of a funnel shape to help get the carbs to go into the insulators. Make sure the upper clamps are oriented so you can tighten them with the carbs seated. They only go one way.
Are these old? They look a bit dirty and maybe damaged, but I can't tell for sure. I'd get new ones, if so. Getting the carbs to seat and work properly in hardened rubber seems like a gamble considering the effort to get to them.
 
Winfried said:
identify where it was leaking from.
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This is a challenge, and in the best case scenario can be difficult to determine because of the airflow around the engine. You may think it’s coming from the left rear of the engine but in fact it will be from the front right……you have to check each clamp in the system to make sure it’s doing it’s job properly, frustrating I know. ;)
 
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The picture I posted is not of the boots I am installing, the picture is something I copied and pasted from the web. The boots I am installing are brand new.

I see that the boots fit with the nib, but the top part of the boot isn't uniform, so I would assume that the top half has to fit properly to the carbs, or does it matter?
 
You know, I started this in November, but I stop every time I am not sure about something as I want to get everything right. The bike rode perfectly until I wanted to do a radiator flush, and found that I had a leak which is why the left side felt hot. Now for a simple leak I have had to tear down the whole top half just to check for where it is leaking from. I took off the radiator, replaced the 4 main radiator hoses and 2 elbow joints, but still can't tell where it was leaking from. I blew through the hoses cupping one end and no air came out so no cracks or holes. I have to put the whole bike together to do a pressure test which I don't want to do. So if not leaking from radiator, the 4 hoses, or the 2 elbows, where else can it leak from?
 
I think you've replaced everything that it could be leaking from, most likely it was from one of the two hoses/elbows under the carbs, that's a common failure point.
 
I can't find any leaks from the hoses and I replaced the 2 elbows. The leaks occured without motor running. Before putting it back together, I want to know what was leaking.

Also, on the insulators, what is the right position to put them back on? Don't want to put them on facing the wrong direction. I put one on the carb and it looks like it is facing the right direction, but want to be sure. I don't want to do any of this again.
 

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