Coolant Leak
- Thread starter Sidewise
- Start date
Uncle Phil
Site Supporter
Since it appears to be a ST1100, I would check the overflow hose just beneath the radiator cap.
I'd also check around the temp sensor and the thermostat gasket located in the same area.
Could also be a loose hose clamp or split hose.
I'd also check around the temp sensor and the thermostat gasket located in the same area.
Could also be a loose hose clamp or split hose.
Yes it is an ST1100. All that seems ok. What is that device with the coolant puddle on top. Hoses, elbows, no sign of leak at thermostat, overflow only wet at that thing indicated in pic.
Uncle Phil
Site Supporter
I presume that shot is from the left side rear of the engine (just noticed the oil filter 
) - the tipover bracket drew my first attention.
If you have a leak at the rear, either you have a cracked block or one of the water necks (there's two) under the carbs is leaking.
I just took a look at a spare engine I have and it has a casted 'hole' there with no cap in it (later model ST1100 2001).
What year is the bike as there are some minor engine differences from the early to later years?
) - the tipover bracket drew my first attention.If you have a leak at the rear, either you have a cracked block or one of the water necks (there's two) under the carbs is leaking.
I just took a look at a spare engine I have and it has a casted 'hole' there with no cap in it (later model ST1100 2001).
What year is the bike as there are some minor engine differences from the early to later years?
Uncle Phil
Site Supporter
In your picture they are the 'nozzles' the two hoses with clamps are attached to.
Looking at the one in the right of the picture, the brown 'junk' seems to indicate a leak to me.
That deep into it, you might consider replacing them (Honda PN#19523-MT3-000 and the o-ring 91331-PC9-003) and all the hoses.
There are a complete set of silicone hoses on EBAY that fit a ST1100 - two of us have already installed them and they seem to work fine -
https://www.ebay.com/itm/2777990866...vDZy4NlZsroD5DRMQLdDUGpw==|tkp:Bk9SR4Dqr4KsaA
For the overflow hose, I use 5/16 heater hose available at most auto parts stores.
The thought is that the silicone ones will outlast the rubber ones.
Looking at the one in the right of the picture, the brown 'junk' seems to indicate a leak to me.
That deep into it, you might consider replacing them (Honda PN#19523-MT3-000 and the o-ring 91331-PC9-003) and all the hoses.
There are a complete set of silicone hoses on EBAY that fit a ST1100 - two of us have already installed them and they seem to work fine -
https://www.ebay.com/itm/2777990866...vDZy4NlZsroD5DRMQLdDUGpw==|tkp:Bk9SR4Dqr4KsaA
For the overflow hose, I use 5/16 heater hose available at most auto parts stores.
The thought is that the silicone ones will outlast the rubber ones.
I presume that shot is from the left side rear of the engine (just noticed the oil filter
If you have a leak at the rear, either you have a cracked block or one of the water necks (there's two) under the carbs is leaking.
I just took a look at a spare engine I have and it has a casted 'hole' there with no cap in it (later model ST1100 2001).
What year is the bike as there are some minor engine differences from the early to later years?
I've had a pressure tester on it, the right side hose is currently not leaking nor the left, coolant is consistently leaking a drop every few seconds but that elbow hoses although looking suspect are not actually leaking. I'm thinking water pipe or cracked block.