Page 1 of 2 12 LastLast
Results 1 to 10 of 20

Thread: coolant leak!

  1. #1

    coolant leak!

    At the end of last season (chicago), i noticed a very small pool of coolant... Oh well.. about 65k on 1999. I'm trying to track down where it's coming from. The pool is centered under block.Ive read about pump, hoses and a lol plastic joint that's prom to failing. Plastic is off bike, and it only happens after cooling from warmed up condition, so right now I know it's small...

  2. #2
    Bush's Avatar
    Bike
    1996 ST1100
    Join Date
    Jun 2006
    Location
    British Columbia
    Age
    68
    Posts
    1,984
    My Gallery

    Re: coolant leak!

    Commonly found to be coming from loose hose clamps on the hoses buried in the engine V, when the drips are coming from the rear of the engine. Also common for the overflow hose to develop a split where it connects to the thermostat housing/rad cap area. Is the overflow bottle full? That would indicate a split as mentioned.

  3. #3
    Erdoc48's Avatar
    Bike
    00 ST1100/94 ST1100A
    Join Date
    Jan 2009
    Location
    Myrtle Beach, SC
    Age
    53
    Posts
    393
    Tip Overs
    1
    My Gallery

    Re: coolant leak!

    One of the more common areas of a leak is the under the carb bank hoses and the aluminum joint where they attach to the head. The aluminum elbows can rot and crack as well as have an O ring seal failure. Also, the hoses are exposed to a lot of heat that can cause failure. It could be a relatively minor leak but you don’t want to have a more major failure when on a longer ride away from home. There are some very good write ups here on how to do the work and I’ve completed the work on each of my 2 STs in the past few months (never did it before and found it all pretty intuitive). It’s actually pretty straightforward if you take your time and are willing to do a little disassembly - if you choose to do the work yourself, I would get all the parts together before doing anything (new hoses, elbows, O rings, etc.). Also, just for completeness, it can be the overflow tube as it tends to get a little dry and brittle vs the bike needing a new radiator cap. Does it run hot? A thermostat could be faulty if that’s the case.

    If you need it, I can look up my Partzilla list of the pieces I bought when I overhauled my STs

    Edit...here’s the list:

    Order Items
    Ordered Shipped Total Price
    16211-MT3-000 - INSULATOR, CARB
    8 8 $70.72
    19503-MT3-000 - HOSE, RADIATOR
    2 2 $24.06
    19504-MT3-000 - HOSE, L. THERMOSTAT
    2 2 $35.64
    19505-MT3-000 - HOSE B, WATER
    2 2 $23.68
    19506-MT3-000 - HOSE, R. THERMOSTAT
    2 2 $30.00
    19523-MT3-000 - JOINT, WATER
    4 4 $33.32
    91331-PC9-003 - O-RING (21.2X2.4)
    4

    Remember, the above is for 2 bikes. Also, I got some 1/4” fuel line for the overflow hose from a local Advance Auto parts, so no need to get this from Partzilla.
    Last edited by Erdoc48; 02-12-2018 at 06:35 PM.
    Bob 2000 ST1100/1994 ST1100 ABS (now in Dark Gray!)

  4. #4
    (Threadstarter)
    MattK's Avatar
    Join Date
    Jul 2016
    Location
    CHICAGO
    Posts
    45
    My Gallery

    Re: coolant leak!

    thanks for the info!! I'll inspect around the overflow.. If it is prings or hoses I'm thinking about jus replacing ALL! prob even the pump just for Peace of mind on long trips! I dont have a prob doimg it myself although i have read some hos kits dont quite fit.

  5. #5
    (Threadstarter)
    MattK's Avatar
    Join Date
    Jul 2016
    Location
    CHICAGO
    Posts
    45
    My Gallery

    Re: coolant leak!

    referances that fit would be great! thanks

  6. #6
    (Threadstarter)
    MattK's Avatar
    Join Date
    Jul 2016
    Location
    CHICAGO
    Posts
    45
    My Gallery

    Re: coolant leak!

    leak is under engine, centered, kinda around oil plug. but haven't seen it drop yet

  7. #7
    Bush's Avatar
    Bike
    1996 ST1100
    Join Date
    Jun 2006
    Location
    British Columbia
    Age
    68
    Posts
    1,984
    My Gallery

    Re: coolant leak!

    Quote Originally Posted by MattK View Post
    leak is under engine, centered, kinda around oil plug. but haven't seen it drop yet
    That could indicate a leaking water pump seal. It wouldn't be a major leak from there, but you can usually trace the dried coolant back up on the front of the engine. The use of a coolant that contained silicates (cleaning agent) can damage that seal. A leak from the V of the engine will normally fall off the rear of the engine, not near the oil drain plug.

  8. #8
    Erdoc48's Avatar
    Bike
    00 ST1100/94 ST1100A
    Join Date
    Jan 2009
    Location
    Myrtle Beach, SC
    Age
    53
    Posts
    393
    Tip Overs
    1
    My Gallery

    Re: coolant leak!

    Interesting idea. How often would the pump seal be expected to leak at 65K miles?

  9. #9
    Bush's Avatar
    Bike
    1996 ST1100
    Join Date
    Jun 2006
    Location
    British Columbia
    Age
    68
    Posts
    1,984
    My Gallery

    Re: coolant leak!

    Quote Originally Posted by Erdoc48 View Post
    Interesting idea. How often would the pump seal be expected to leak at 65K miles?
    Using the proper coolant, one would never expect to see that pump fail at 65K miles, but I, unfortunately, speak from experience.

    On my previous '95 model, bought new and when I was uneducated about the contents of coolant, I used a regular auto store coolant that required me to add the distilled water 50/50. That was after four years and about 30,000 miles. Changed it again three years later and at 55,000 miles, with the same stuff, since a gallon jug goes a long way!

    A year and a half later and about 60,000 miles, the pump was leaking. Then I found out, on a forum, about the silicates in some coolants and the danger they posed. Using Honda Type 2 ever since.

  10. #10
    STOC #687 dwalby's Avatar
    Bike
    '97 ST1100
    Join Date
    Mar 2012
    Location
    San Diego, CA (San Pasqual Valley)
    Posts
    2,537
    Tip Overs
    2
    My Gallery

    Re: coolant leak!

    Agree with Bush, the hose leaks from the engine V drip well to the rear of the engine, oil drain plug area is something else.

    But, if you're riding a '99 that's never had the hoses in the V replaced, its time to do it, they're just waiting to split. When the hoses fail they split along the length of the hose and your coolant blows out almost instantly and leaves you stranded.

+ New Posts
Page 1 of 2 12 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •