Breather pipe weeping (Concluded)

[st1300marc]

I have what appears to be a slight weep of oil which appears to drop from one of the two breather pipes at the bottom of my 2004 St1300, it's not a huge leak approximately the size of a Uk 50p coin

Any ideas? Maybe even if you chaps/chapettes could clarify where the two breathers go to would aid my search

 

[ScubaDave]

One of those comes from the air box. I have seen a drop now and then from it. If its just that I would not think is anything to worry about. Another is from the gas tank. You would need to see what one it is coming from to really know if you have an issue. Also does it keep dripping or is it more like a couple drops a year thing.

 

[Al st1100]

slight weep .. normal

 

[Igofar]

A few things to check....
Has the engine oil ever been over filled? If so, check the air box crank case breather to see if oil is in the airbox.
Also, check to make sure that a leaking oil filter is not just following the line down and dripping from it.
Are you sure its oil, and not a coolant leak mixing with road grime, that appears to be oil?
A loose drain plug will also allow oil to follow the transmission pan fins rearward and blow onto the lines etc.
What oil filter are you using? Some aftermarket filters have been known to leak (including K&N oil filters) etc.
Can you post a picture of the area so we can help advise you more?

 

[st1300marc]

little update....

* Over the last fortnight I have repaired a sticking fuel cap, gently filed the edges of the two locking pins

* After this I brimmed the tank upto the metal bar in the filler neck

* At the same time we've had a rapid increase in temperature and sunshine in the UK (16-18'c)


Am I right in deducing that a brimmed tank and a bike sat in direct sunlight may produce fuel vapour seepage from a breather pipe and mark the asphalt underneath the bike?

 

[st1300marc]

I've owned this St1300 this September 2018 and never had an issue before or changed/topped up the oil

There is no obvious leaks from the sump, drain nut or oil filter

I did fix a weeping left valve cover gasket back in January........never weeped enough to drop oil onto the floor

 

[CYYJ]

Am I right in deducing that a brimmed tank and a bike sat in direct sunlight may produce fuel vapour seepage from a breather pipe and mark the asphalt underneath the bike?

If you have only filled the tank up to the metal bar below the filler neck, I think it is unlikely that sunlight & air temperature rise would cause fuel to overflow. I believe that the horizontal metal bar is there to indicate what safe expansion area should remain in the tank to prevent exactly that problem.

Michael

 

[st1300marc]

If you have only filled the tank up to the metal bar below the filler neck, I think it is unlikely that sunlight & air temperature rise would cause fuel to overflow. I believe that the horizontal metal bar is there to indicate what safe expansion area should remain in the tank to prevent exactly that problem.

Michael

Well that's that theory gone, some further investigation required

 

[st1300marc]

Just had a quick peek and it's becoming a little obvious that it's not an oil leak

 

[Andrew Shadow]

That is where coolant seeps out if you have a leak from the hoses under the throttle bodies.
Looks to me like you have the common problem of a coolant leak due to insufficiently tightened clamps on the coolant hoses under the throttle bodies.

If you want to tighten them up- access coolant lines
If you want to change the clamps for constant tension clamps- ST1300 - Solving the Coolant Leak Problem... For Good

 

[st1300marc]

I brimmed the expansion bottle which took between 500-650ml of water and removed the lower fairing panel to make a leak trail more obvious

Upon riding 10miles home and turning the bike off the bike leaked from the expansion bottle only......nothing from the front of the engine

Temperature on my morning ride is 4'c and the ride home is 16-18'c if that makes a difference?

 

[CYYJ]

That is where coolant seeps out if you have a leak from the hoses under the throttle bodies.

Exactly.

Drain lines at the bottom of the ST 1300 are found in two places: There is one drain line / drain area at the very front of the engine, which you provided a picture of in your post #9 above, and another set of drain lines at the rear of the engine (picture below).

The drain line / drain area at the front of the engine serves the "square hole and round hole" that are found near the water pump. See this post for an illustrated explanation: water pump weep holes. There is also additional information and pictures showing an older model ST 1300 at this post.

If you are going to start investigating the source of your leak, you might want to browse this rather long discussion, which not only addresses finding and fixing coolant leaks, but also other maintenance tasks that can be carried out when you disassemble to find the coolant leak: ST1300 - 1st Significant Service: Coolant, Thermostat, Starter Valve Synch, & Other.

There are several hoses (3, I think) that exit at the back of the engine. One of them is the overflow drain from the area around the top of the fuel filler port (the small hole you see at the 10 o'clock position when you open the gas cap and look at the moat around the filler port). I'm not sure what the other hoses there are for - I suspect one of them probably attaches to the charcoal canister that deals with fuel vapour, and the other might be the overflow cap from the coolant reservoir that is on the left side of the motorcycle, just forward of where your left shin is when you sit on the motorcycle.

Michael

Drain Hoses at Rear of Engine

 

[st1300marc]

I removed the side cover and let the bike idle upto normal operating temperature but no leaks were visible. However it does appear evident that there have been leaks from both the weep hole and valley area



I shall report back in the morning when I have completed my 10 mile ride in 1-5'c temperature......maybe I have a coolant leak when the ambient temperature is cold

 

[CYYJ]

Hi Marc:

I think you will find that coolant leaks correlate more with engine RPM than with coolant temperature. As RPM increases, coolant pressure in the water pump increases (hence leaks from the "round hole"), and coolant velocity and pressure increase further upstream at the thermostat and hoses directly behind the thermostat (hence leaks from hose clamps that result in coolant dripping out of the "square hole").

To avoid possible confusion, be aware that if you thoroughly wash your moto with a power washer or a garden hose and succeed in spraying water into the V between the cylinder banks, that water will then run out the square hole. Don't misinterpret that (water out of the square hole as a result of energetic motorcycle washing) as a coolant leak.

Based on the picture you posted above in post #13, I think you have a "round hole" leak, which implies leakage within the water pump. You may also have leakage from the square hole, which implies hose clamp leaks within the V of the engine. If I were you, I would scrub it all down with degreaser until the whole area around and under those two holes is clean, then watch it over the next few weeks until you can determine exactly where the leak is coming from.

Michael

 

[st1300marc]

Closure to this thread

My problem was multiple small coolant weeps in the thermostat and front of engine area. Underneath where the rubber pipes push onto the aluminium had also mildly corroded which didn't help


After removing the Tupperware and radiator I managed to do the job from the front of the bike, I cleaned up the corrosion and changed the standard hose clamps with stainless steel JCS hi torque items

2 weeks later and no sweet whiffs of coolant for me...........FOR NOW! Lol


This is a very time consuming and fiddly repair, there is very little room to work around the thermostat

 

[CYYJ]

This is a very time consuming and fiddly repair, there is very little room to work around the thermostat

That is very true.

This past winter, I took the throttle bodies off to let me get to all the hoses and replace some, tighten some up, replace a few clamps, and clean out the debris under the rubber heat protection mat. I think that's the best way to deal with coolant leaks from the hoses - wait until winter, then just take the whole thing apart. That enables a bunch of other preventative maintenance tasks at the same time - washing out the radiator, cleaning the "square hole" drain path, making sure the heat mat is in the right place, etc.

There are a few photos showing the coolant plumbing and thermostat with the throttle bodies off at this post: Coolant Leak.

Michael

 

[bdalameda]

Hi Marc:

I think you will find that coolant leaks correlate more with engine RPM than with coolant temperature. As RPM increases, coolant pressure in the water pump increases (hence leaks from the "round hole"), and coolant velocity and pressure increase further upstream at the thermostat and hoses directly behind the thermostat (hence leaks from hose clamps that result in coolant dripping out of the "square hole").

To avoid possible confusion, be aware that if you thoroughly wash your moto with a power washer or a garden hose and succeed in spraying water into the V between the cylinder banks, that water will then run out the square hole. Don't misinterpret that (water out of the square hole as a result of energetic motorcycle washing) as a coolant leak.

Based on the picture you posted above in post #13, I think you have a "round hole" leak, which implies leakage within the water pump. You may also have leakage from the square hole, which implies hose clamp leaks within the V of the engine. If I were you, I would scrub it all down with degreaser until the whole area around and under those two holes is clean, then watch it over the next few weeks until you can determine exactly where the leak is coming from.

Michael

In my experience coolant leaks most frequently begin to show up on the ST's during cold winter months when sitting in the garage or minimal running. This is mostly due to the hoses shrinking and the clamps loosening. Also the o-rings can shrink. Many of these leaks will stop after warming the engine up, when things expand and get tight the leaks stop. Constant tension hose clamps can stop this from happening.