HELP... Mysterious Coolant Leak

Joined
Sep 3, 2007
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66
Location
Bryan, Texas
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1999 ST1100
Guys and Gals,

I had a coolant leak previously last year from the valley under the carbs. That is fixed and the fittings are tight! I had to take the carbs off two other times, both due to leaks, and I know they are tight.

However, now I have a leak from the same(ish) area that is presenting on the front left side of my block. The thing that make me think it is different from the valley is a slightly different presentation and thinking that there is a weep hole that goes to the water pump (this should go to the underside of the cover that encases the timing belt). Hope that makes sense. Please see pics below.

In one of the pics below I circled where the leak is coming from (or is making its way externally).
 

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John OoSTerhuis

Life Is Good!
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Bettendorf, Iowa
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1991 SSMST1100
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1058
Hi David. The water pump weep hole is a rectangular hole. Can't tell if that's the source from the pictures, but it doesn't seem like...

Did you replace the bypass hose? The one from the thermo housing to the nipple in the water pipe (just behind the water pump housing on the left side). I can find a picture if you need it.

John
 
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dualsportdave
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Sep 3, 2007
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Bryan, Texas
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1999 ST1100
John,

I am pretty sure I did in fact replace that hose. Most of my hoses were at the end of their life last year. Could you please send that pic though. Anything helps.

Also, just clarifying the leak is on the left side of the bike on the front of the block.
 

John OoSTerhuis

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1991 SSMST1100
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1058
You made it sound like your previous fixes were just tightening hose clamps. With that, and no clear indication of the water pump weep hole as the source, I went to the next candidate for a forward left side coolant leak. You wouldn't be the first to have a bypass hose leak.

I'll jump on the desktop later and dig up some pics.

John

via iPhone 4S
 

ST1100Y

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Agree with John... bypass hose, w/pump seal or the steel pipe/flange (radiator return line)...
Pull the carbs and check for the traces/deposits which will lead you to the source.
 

John OoSTerhuis

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Location
Bettendorf, Iowa
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1991 SSMST1100
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1058
The bypass is the one on the right connecting to the Water Pipe:



Thought I had a picture of the water pump weep hole 'in situ' but can't find it. Here's one of the pump removed from the bike:

water pump backt-jschneider.jpg

HTH

John
 
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dualsportdave
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Sep 3, 2007
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66
Location
Bryan, Texas
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1999 ST1100
John,

Thank you for the great pictures. Also, thank you for the great advice. I will have to find time to find this problem and I bet you it will lead me right to the places that you stated.

Really guys and gals,

Thanks
 
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