Coolant Leak Left Side ST1100

john.berg

I have developed a coolant leak, it appears on the left side. I don't think it's the normal under the carb leak, I replaced the hoses under the carbs and the upper and lower radiator hoses less than 1k ago and also resealed the elbows (seperate item but when I pulled the elbows there was no orings or groove for orings in the elbows so I used a silcone sealer).

The leak comes down the left side of the belly pan in front of pegs and sidestand so I'm assuming it's not under the carbs.

The odd thing is it drips about a tablespoon of coolant when cold then it stops once it's even slightly warm. I notice in the schematics there is a metal pipe from the lower radiator hose to the block, anyone experince leaks here?

Any ideas before I pull all of the plastic? I thought I would ask so I could have any parts needed in hand before starting.
 
You should be able to take the lower cowl off and look up inside to see where the leak is. There is a lower hose on the left side that can weep if the clamp loosens up.
 
Sealing the elbows other than using orings throws up a red flag right away.....not saying that's the leak point, but suspicious.....JAT. The small bypass hose runs over to the left side in proximity of the lage radiator hose, and those are on outside of block....maybe worth a look removing the cover where valve cover is located. Coolant CAN run out frontside same as backside if leak is associated with elbows.........:(
 
john.berg said:
I have developed a coolant leak, it appears on the left side. I don't think it's the normal under the carb leak, I replaced the hoses under the carbs and the upper and lower radiator hoses less than 1k ago and also resealed the elbows (seperate item but when I pulled the elbows there was no orings or groove for orings in the elbows so I used a silcone sealer).

The leak comes down the left side of the belly pan in front of pegs and sidestand so I'm assuming it's not under the carbs.

The odd thing is it drips about a tablespoon of coolant when cold then it stops once it's even slightly warm. I notice in the schematics there is a metal pipe from the lower radiator hose to the block, anyone experince leaks here?

Any ideas before I pull all of the plastic? I thought I would ask so I could have any parts needed in hand before starting.
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I bet the bottom of the elbow had black circle stain???????? This stain is the old o-ring. Mine were the same. I even asked on forums if they had a o-ring grove. They do. Got ta dig them out. My 1st guess is the leak is the siliconed sealed elbows, followed by the 1/4" bypass hose. When I changed out my hoses, the originals looked pretty good except the bypass hose which was hard as a rock. That metal pipe O-ring will be a big time booger to get to. I didn't mess with mine.
 
+1 on what Raiph said about the elbows and bypass hose (my guess for the leak).


John OoSTerhuis STOC 1058

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John OoSTerhuis said:
+1 on what Raiph said about the elbows and bypass hose (my guess for the leak).
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Slam dunk! Those things get so baked and hard that if you didn't know there were O-rings there you would make the assumption that you did. Don't feel bad though, I wondered for a bit how the heck Honda had pulled it off. Take your elbows off and if you don't want to wait for, and pay shipping on two o-rings, get some at an auto parts store or hardware. You want them to be about .010 to .015 higher than the surrounding aluminum for a compression seal.
 
BuddingGeezer said:
My 1st guess is the leak is the siliconed sealed elbows
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It is amazing to me that the elbows stay sealed after the rings get hard. There must be enough antifreeze sludge forced into the minute gaps that it self seals. Amazing to me that the heat/cool cycles don't keep that from working but it does in most cases, apparently.
 
Could you guys point out the bypass hose # on the fiche? Planning on doing hoses (and o rings) over the winter. Thanks.
 
DeanR said:
Could you guys point out the bypass hose # on the fiche? Planning on doing hoses (and o rings) over the winter. Thanks.
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Dean, the bypass hoss is the small one on the right side of the picture leading to the Water Pipe:



The picture is a link to the whole album of my coolant hose R&R pictures (with captions).

edit: item 16 here in the AOW article: http://www.st-riders.net/index.php?topic=3523

Regards, John
 
Oh my gosh, your exactly right. When I pulled the elbows there was a dark ring, looked nothing like an oring and I used a pic to try and loosen the material but it wasn't going any where so I assumed.....

Looks like Im pulling it apart again, so should I just order new elbows to be safe (I still have the orings I ordered and found the new bolts I had ordered also.

Does anyone know the schematic number for the bypass hose?

This all makes sense now, I had replaced the overflow hose a week ago and the leak started. I'm guessing because the appeared because I haven't been able to keep the block full of coolant (constantly over running the overflow tank) or its cold enough now the leak now appears
 
Elbows will be fine if new,if not get two new ones [just done mine too] Part 16 on the image should be the overflow pipe you need http://www.pan-europe.utvinternet.ie/parts/water_pipe.htm

16 95005-55380-20 TUBE? 5.3X380 (95005-55001-20M)

6f8909023d60c9b0a160dddb003096da.png
 
Andi As said:
Id say the high level of heat in that area combined with the number of years they are fitted
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They go through so many heat/cool cycles that they get cooked. I would bet Honda learned from this application and did not repeat it.
 
John OoSTerhuis said:
Dean, the bypass hoss is the small one on the right side of the picture leading to the Water Pipe:



The picture is a link to the whole album of my coolant hose R&R pictures (with captions).

edit: item 16 here in the AOW article: http://www.st-riders.net/index.php?topic=3523

Regards, John
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WOW!!! :bow1: John, I just bought a 1993 ST1100 with only 50,000 miles on it. It was ridden on and off. After pulling off the covers when I got it home, I see the exact same evidence of small leaks that you have so I am replacing all of the hoses, Thermostat, Overflow hose to the reservoir and stuff today. I just ordered all the hoses from Honda and will get them tomorrow. Your link has given me an incredible insight to what I NEEDED before I get started. YOU ROCK!

Hope you are still around on the FORUM.. God bless
:biker:
 
TopGunPilot said:
WOW!!! :bow1: John, I just bought a 1993 ST1100 with only 50,000 miles on it. It was ridden on and off. After pulling off the covers when I got it home, I see the exact same evidence of small leaks that you have so I am replacing all of the hoses, Thermostat, Overflow hose to the reservoir and stuff today. I just ordered all the hoses from Honda and will get them tomorrow. Your link has given me an incredible insight to what I NEEDED before I get started. YOU ROCK!

Hope you are still around on the FORUM.. God bless
:biker:
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Hope your pulling that carb bank and replacing those elbows and o-rings too. If the elbows aren't fractured, guarenttee they soon will be and you'll be right back in there re-peating what should have been done the first time.
Reason for replacing elbows, even if they look fine: the elbow casting mounting holes location has one side taller than the other(who knows why, cept maybe to cover different applications). The metal not being equal amount on both sides heats and cools at different rates, causing more stress on one side than the other.........ain't rocket science....but metalurgy helps;)......replace them, period:).
 
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