Water Pump Leak Unusual

[Andrew Shadow]

You can get to the thermostat by removing the radiator and frame brace behind it.

Good point this. You may not even need to remove anything depending on which hose is leaking.
With a few creative tool combinations I managed to tighten all of mine by sneaking in through various openings at different angles with different length screwdrivers, bits on 1/4" drive extensions, etc.. Other than lifting the upper fuel tank in to the maintenance position, I never removed anything and I was able to the leak.

 

[marc11]

You don't really need a siphon. If you don't want to wait for it to arrive, see the below method that will drain all but a few ounces of fuel from the lower tank.

Draining the Lower Tank
(Courtesy of John, AKA BakerBoy on ST-Owners.com)

If you want to drain both of your fuel tanks, leaving only a small amount of gas where the pump doesn't go, remove the hose labeled #6 in the below picture and QUICKLY attach a similar size hose to the exposed nipple. Lead the hose to a very big gas can!

1. Have a big gas can with you!
2. There will be hardly any gas left in either fuel tank.
3. Be quick swapping the two hoses when you first start out. You will lose a little gas, but the quicker you are the less you will lose!

The below photo shows the lower fuel tank hose connections.

There are 4 fuel connections on top of the lower fuel tank, numbered as indicated in the picture above:
1- Small hose that vents lower fuel tank vapours into the upper fuel tank.
4- Large hose that connects the upper fuel tank to the lower fuel tank.
5- Pressurized fuel delivered out of the fuel pump to the fuel rail above the throttle bodies.
6- Depressurized excess fuel returned from the fuel rail.

The image below shows the upper fuel tank hose connections.

1- Vent tube to allow air to escape the lower fuel tank during fill-up.
2- Breather tube connected the charcoal canister.
3- Drain tube to evacuate fuel spills or water from around the upper tank filler neck.
4- Large hose that connects the upper fuel tank to the lower fuel tank.
A- Electrical harness for the fuel level sensors.

So the fuel will come out of the fuel pump side once I remove hose as it is being fed from the upper tank and being forced out by the gravity feed from the upper tank? Any idea the size, 3/8 or 1/4?

 

[marc11]

You can get to the thermostat by removing the radiator and frame brace behind it. This is easier than going down from above (which involves removing the tank air box, etc.). Most of the leaks I have heard about were from hose clamps on the big hoses - stat housing and radiator. If you do go down from above, be sure to throw your philips screw driver away and only use a JIS screw driver on the airbox screws. They can be pretty tight. A philips will cam out and damage the screws.

Thanks, I have a set of JIS screwdrivers, been burned way too many times by trying to use a Phillips on front master cylinder screws....

 

[SMSW]

I think you will use the fuel pump to pump out the gas. Guys who have done this will chime in soon.

 

[Andrew Shadow]

So the fuel will come out of the fuel pump side once I remove hose as it is being fed from the upper tank and being forced out by the gravity feed from the upper tank?

I think you will use the fuel pump to pump out the gas. Guys who have done this will chime in soon.

No fuel pump needed.
If you keep the hose to your catch container below the level of the bottom of the lower tank, and if you don't stop the flow at the wrong moment, pressure due to gravity takes care of draining most of it and regular siphon action takes care of sucking up the last bit from the bottom of the lower tank.

 

[Kevcules]

Sounds like it's drained out instead of being pumped out.
I haven't used that way yet. I just put a clear vinyl tube into the large upper tank and start the fuel running with a quick "suck" on the hose and it drains most of the fuel from that tank.(Wouldn't try it without clear hose anymore, sucked in some gas a long time ago and won't do it again. ) Then I only lose a little fuel when I disconnect the large tube at the bottom of the tank.
This way sounds like a good option to try though in the future....
Measure the fuel hose diameter currently on there and have a replacement ready.
Good luck....

 

[Andrew Shadow]

Any idea the size, 3/8 or 1/4?

Original from Honda is 5.5mm inside diameter, which is right about in the middle between 3/16" and 1/4".
I didn't pay attention to what I used- something that I had on-hand. I'm sure that you could force 3/16" on and 1/4" would work just fine with a clamp on it.

 

[dduelin]

You should find the prop rod secured in the aft section of the bike under the seat. It used to prop up the upper fuel tank. Find the section in the owners manual page 93-94 that shows it and how to slide the upper tank back into the maintenance position using the seat adjuster. It's easier of course with an empty tank but not it is not necessary to have the tank empty to lift it. Manual even points that out. It is VERY IMPORTANT however to secure the seat adjuster in the maintenance position before lifting the front of the tank.

Like Andrew said it's possible with the right tools to get to the leakers without lifting the tank and removing the airbox and heat mat. Remove the radiator and come in from the front.

 

[marc11]

Well, a bit late, but the tank is off and the bike and a good part of my garage floor has been "washed" with about half a gallon of fuel, what a PITA that tank removal is, the airbox is out, the screws holding the lower airbox to the intake manifold must have been put in by godzilla's cousin....even with a JIS screwdriver three screws cammed out and stripped, I got them out, but they will need replacing.

Anyway, I am there, and NOW I see how removing the radiator and going in from the front was a much better approach...anyway, I do not see any obvious signs of leaks, I will run the bike tomorrow and look, but I do see some staining, but that could be from water, the only thing I noticed is the back of the T-Stat, there is a nut holding in something, I couldn't see, maybe a sensor, but that nut is green, it stands out from the rest as being green....made me go hmmm

Question, are there connections under the manifold and mat? Not sure if I need to pull the intake, I would prefer not if I do not have too.

 

[dduelin]

Sounds good! The sensor in the T-stat housing is the coolant temp sensor. The O-ring that seals the two halves often is a leaker. Under the throttle bodies, IIRC, there are small hoses to the wax pellet thing for cold start bypass and to the oil cooler. These small hoses tend not to leak or cause problems.

 

[Rob20111]

My leak was from a bad thermostat housing O-ring and some loose hose clamps at the top front of engine. All were accesible with the rad out, which was quite easy to do.
While inside the housing I also found the T-stat was bad (stuck open) and replaced it.
1 year later and no leaks (so far).

 

[marc11]

Thanks, I will run the bike after work today and see, if it is the o-ring I will also replace the t-stat since it would be silly not to for $45! Fingers crossed its the o-ring and I do not need to pull the intake. I sure am getting to know this bike quicker than expected....

 

[MattSTlouis]

You can get to the thermostat by removing the radiator and frame brace behind it. This is easier than going down from above (which involves removing the tank air box, etc.). Most of the leaks I have heard about were from hose clamps on the big hoses - stat housing and radiator. If you do go down from above, be sure to throw your philips screw driver away and only use a JIS screw driver on the airbox screws. They can be pretty tight. A philips will cam out and damage the screws.

Never heard of a Japanese Industrial standard screwdriver or why those phillips screws were such a pain. I will order one today though.

 

[SMSW]

Never heard of a Japanese Industrial standard screwdriver or why those phillips screws were such a pain. I will order one today though.

Phillips were designed (I think) to limit the torque. Anyway, they will cam out when twisted too hard and damage the screw slots in the process. JIS have more vertical wings and are less rounded where the wings join.

Purloined shamelessly from Wikipedia: Phillips screws - The design is often criticized for its tendency to cam out at lower torque levels than other "cross head" designs. There has long been a popular belief that this was a deliberate feature of the design, to assemble aluminium aircraft without overtightening the fasteners.[14]: 85 [15] Extensive evidence is lacking for this specific narrative, and the feature is not mentioned in the original patents.

JIS - The JIS B 1012[26] was commonly found in Japanese made equipment, such as cameras and motorbikes. Superficially it looks like a Phillips screw with narrower and more vertical slots, to give less tendency to cam out. The bottom of the recess is flat, and the point of the driver has to be blunt. A Phillips screwdriver has the same 26.5 degree cone angle but because of the tapered slots will not seat fully, and will damage the screw if forced. A correctly sized JIS driver will engage at full depth into a Phillips or Pozidriv head screw slightly loosely, but without damage. JIS heads are often identified by a single dot or an "X" to one side of the cross slot.

 

[marc11]

Welp I am at a loss; this AM there was a small puddle under the bike of coolant again, so clearly the leak is active whether the bike is running or not. Not being able to see where it is coming from, I removed the radiator and bracket, everything I can see at, under and around the hoses and t-stat are bone dry. I would have expected, with an active leak and fluid on the ground to find evidence of coolant at the t-stat and or hose area, but it is all dry.

I am officially stumped and am being lead back to, could it be the o-ring gasket that seals the pump cover to the pump?

 

[Andrew Shadow]

Was it cold overnight where the bike was sitting? i.e. Unheated or low heat environment. If so, still sounds like one those loose hose clamps if you didn't manage to get at all of them. Common problem with the ST1300. Many have referred to it as morning sickness.

 

[marc11]

Was it cold overnight where the bike was sitting? i.e. Unheated or low heat environment. If so, still sounds like one those loose hose clamps if you didn't manage to get at all of them. Common problem with the ST1300. Many have referred to it as morning sickness.

Yes it was cold overnight with garage windows open due to fuel spill. But wouldn't I see wetness in the V?

 

[marc11]

Checked all the clamps. All loose, tightened them all. One was bad, it just clicked and would not tighten, replaced it and one on the lower houses by the pump was oblong, replaced it.

Ordered a new t-stat and o-ring will swap them before putting it back together.

After that, it's in God's hands.

 

[Andrew Shadow]

Yes it was cold overnight with garage windows open due to fuel spill. But wouldn't I see wetness in the V?

Depends which one is leaking.

 

[Andrew Shadow]

Checked all the clamps. All loose,

Common issue.

one on the lower houses by the pump was oblong, replaced it.

Take care not to over-tighten the hose clamps on the radiator hoses. The radiator inlet/outlet pipes are soft and can deform if the clamps are over-tightened.