ST1100 coolant leak

major domo

Joined
Aug 20, 2012
Messages
21
Location
Athens
A few days ago, I was in the process of changing coolant on my '93 ST. I had the engine running so that I could slowly add coolant as the system "burped" out excess air. At no time did the temp gauge rise above one quarter.ST 1100 coolant leak area.JPG I noticed a pretty good leak coming from the left rear (as you sit on the bike) of the crankcase, just about 5 inches above and to the right of the oil filter. It seems to be coming from the area of the large, circular plug (with allen head fitting) at that location, but can't be certain. See attached photo of the area where it is leaking. Any ideas?:confused:

Thanks in advance!
 
That's the area that green blood was flooding from when I found it pouring out at a stop light.
I found a broken Al elbow underneath the carbs.
You might want to:
Disconnect the fuel line from the gas filter and empty your gas tank into a gas container.
Disconnect the 3 wires from the top of the gas tank and the one from just in front of the battery (hard to see as it sits behind a frame member).
Disconnect the 4 bolts holding the tank in the frame.
Pull the tank.
Put in more fluid and then start the bike again or go borrow a pressure tester from Autozone or O'Rielly's (which is what I did) to see where the leak is located. A flashlight helps...

Remember to order 2 elbows and 2 o-rings if the leak is from one of the elbows as you *do not* want to have the other elbow go south 1000 miles after you fix one of them.

Let us know!
 
+1 on Marks reply. Becoming a more common issue as these ole' 11's age. Just normal procedure, not uncommon........and the 13's WILL fall in line eventually as they age. Pay special attention to orientation of each boot before removal, as this WILL affect accessability of screw clamps. Also, throttle and enricher cables do NOT have to be remove to do this little chore. Just set carb bank off to RIGHT side where glove box assembly WAS during repair. Spray a little shot of silicone on boots before installing carb bank too.
 
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had the same issue with mine just a week after I bought it. The dealer that sold it to me was great and took care of it as part of the initial purchase. They replaced both elbows and o-rings. They are not a Honda dealer (kaw, suz, triumph) so of course *I* had to show them where the leak was coming from. They could see the green blood trail running down the back of the engine but didn't see from where. I provided them photos of the top under the carbs and pointed it all out and they then easily found the trouble with one, and replace the other at the same time.

This weekend I found the next possibly common issue with coolant. The mounting lug on the back side of the coolant recovery tank has a crack in it so leaks a little bit of coolant every time it gets warm out. Time for a new one of those.
 
When I did mine I changed the hoses as well. From start to finish I got it all done in about 4 hours. That included changing the thermostat and since I could not source an o-ring locally I had to make one and let it set. Once all back together and cured I got a cooling system pressure tester from the local car parts store and put the whole system under pressure for an hour to ensure I would not get any leaks after getting it all together. All said, plan for a full day to get everything done start to finish.
Tony
 
This might be redundant, but, with the carbs out of the way, check the clamp on the PAIR valve hose directly under the upper coolant hose at the right-front (cylinder #1) of the engine. That clamp can intrude on the main coolant hose and eventually rupture it. AMHIK. :D
 
Thanks to all for the imput on this. The bike is still down, awaiting a mechanic friend to squeeze it in. I just may tackle this myself.
 
Hi Mark,

Do you have part #'s for those elbows & o-rings, so I can locate them easier on a parts fiche? I assume these are on parts page titled "Water Pipe"?

Thanks!

Ken
 
Thanks, c130flteng!

BTW: Still in the Air Force as a Herc Flt engineer? I'm retired ANG photographer.
 
Hey George,

Thanks for the tip. That clamp is right up against the hose. so I'm going to turn it,or put on a different-style clamp.
 
I've been waiting for a friend's mechanic to get back to me to make the repair, but time is getting to be a factor, as I'm leaving for the Barber Vintage Rally in about 2-1/2 weeks. So... I decided to try and tackle this myself (que quaking in boots music). After reading numerous posts regarging this problem, I started yesterday to track down the leak (suspected elbows at the head). Fuel tank removal piece of cake, as were the carbs, (thanks to thread about using broom handle!), due to the fact that several boots were loose! Blame that on last major service at a Honda dealer (to remain anonymous!). Found evidence of coolant leak from RH elbow. No cracks in either elbow, but o-rings are in bad shape. Both elbows and o-rings wll be replaced, along with all major hoses, radiator cap and thermostat. Just ordered parts this AM. Thanks for all the imput on this! Great site!

Was thinking of selling the bike for a crusier, but just may have to keep it. The seat (modified by Sargeant) will have to go, as it's not much better than stock, and will probably opt for Meyer Day Long. Other mods will be Heliibars (had for a few years now, but never installed), better windscreen (has Clearview), and maybe some type of hiways pegs.
 
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While you are in there, and since you are ordering parts, if the carb isolators have not been changed in the last few years get those as well. It will not only make putting the carbs back easier but will keep you from developing a lean cylinder now that they have been disturbed. The first time I removed the carbs I did not do this and wish I had followed the advice of this forum. All four looked to be in good shape with no cracks. They were pretty hard and just would not seal. If you are heading to a rally in a couple of weeks you don't want to have a lean condition on the ride. Could force you to buy that new bike if you blow a cylinder.
They are number 4 here
http://www.bikebandit.com/houseofmotorcycles/1995-honda-st1100-st1100/o/m151501#sch30456
 
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Cool. I retired in 2011, with 35 years service with a KC-135R tanker unit, out of Milwaukee, Wi.
 
whenever you need something (parts) look on partzilla.com. They get their parts right from Honda at really super prices. Schematics with real part numbers also.
 
Thanks to all for the help regarding my coolant leak. I replaced the elbows under the carbs, along with new hoses, to include both radiator hoses, elbow hoses, rad.cap overflow hose, and coolant overflow tank hose. Also replaced were the radiator cap, thermostat, radiator drain plug, and thermostat housing 0-ring. Honda Type 2 coolant was used. Carb boots, which had been replaced some years back, where/are stil nice and pliable; carbs went back in with no problem (used just a bit of silicone grease to ease them in). The job was easier than originally envisioned. Started and ran bike to temp, bled the system, fan kicked in as it should, and no leaks! Went to the Barber Vintage Festival this past weekend, and had no issues whatsoever! Thanks again!
 
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