Fluid leak near the VEE???

I discovered a fair amount of oil on my floor after a short ride to meet Shuey for Supper Sunday night. I traveled, maybe 7 mile at the most and just 2 miles to get home.

There is fluid on the front of the oil pan and cooling fins. Inside the front of the lower cowls.

Took the right side plastic off tonight to get a better look. No real sign of where it was coming from. Cleaned the water and clutch cover housings. Started the bike and let it idle for a good ten minutes. Nothing, nota drop. Increased the RPM's to about 3k, shortly a stead flow of what looked like oil came out from between the Water and Clutch housing. Next step with the help of Scooter on the phone, pulled the air box and inspected the valve cover gaskets, no leaks. Looked under the mat as best as I could. Did not see any fluids. Ran the bike again watching for upper leaks. Nothing. At the higher revs now I am getting coolant colored fluid from the same area between the two covers, NOT the ROUND weep hole.

Next step - pull the radiator and tighten hoses at the Tstat and R & R that "Mystery" plug.

Any one with the same symptoms that has a fix, please reply as I have a long planned trip to the Pacific ocean leaving on 9-12.

Thanks in advance, Kevin

Kevin, it sure sounds like that plug at the front of the motor leaking as it sounds like you have looked at the other possible areas. Let us know what you find.

keep us posted

Crap!!! Good luck Kevin!

While your checking the clamps pull the mystery plug and clean it then apply some hondabond to it and replace it.

Here are a few threads that have some good information.
Gotta check my mystery plug when I remove the rad for a coolant change.

https://www.st-owners.com/forums/showthread.php?122213-Not-antifreeze-but-oil-leak

https://www.st-owners.com/forums/showthread.php?123950-Oil-leak

Coolant would indicate a leaking hose clamp. There are so many in the area it's hard to say which one. Could be a small one that feeds the throttle bodies, or it could be the bigger ones that come out of each head. Doesn't really matter as they all need tightened up while your in there.
Since yours is an 03 then the mystery plug should be sealed since you will be that close. If just for piece of mind.

One common source of coolant leak that a lot of folks miss are the two small coolant lines that come off the t-stat housing. These are plated metal, and can often rust and pit underneath the clamp area. No amount of tightening of the clamps will stop the leaks unless you take the time to remove the hoses and clean the pipe fitting. I've found some so badly pitted that JB weld had to be used (emergency fix) to fill in the pits and then sand back down to the original shape before re-installing the hose again. You may want to remove all the hoses and check the condition of the pipes. .02

I hate to report that after removing the mystery plug, applying sealant and reassembly, I still have a steady stream of oil at 2500 rpm.

Off to camp and wait for your actual experience on what else can be leaking. I have eliminated the valve covers earlier.

Over many years at dealerships I've seen a few oil presure sensors leak by the top screw fitting. Just about all of them look just like the ST's but in different locations. I have an extra if needed.

I guess I'm confused if the fluid at 2500-3000 rpmis coolant or oil. Different posts said different things.

Fluid coming out the square drain opening next to the tiny round water pump weep hole drains from above. Ruling out the gallery casting plug, oil could conceivably leak out under pressure (operating oil pressure is 80 psi IIRC) out of the oil pressure sensor in the floor of the vee or perhaps out of the alternator gear drive. The alternator drive if leaking would be wet under the alternator itself. A large O-ring seals the alternator to the drive.

The pipe joints bolted to the cylinder heads are sealed with O-rings that flatten and harden with heat and miles. Fresh coolant obviously look and feels very different from oil. Old coolant leakage mimics an oil seep but a flow of coolant at 3000 rpm in my mind is not going to look or feel or taste/smell like oil. Larry also mentioned that corrosion in fittings under hoses could cause coolant leaks.

Here is a picture that Kevin texted to me the other day...



When he initially called me he was reporting an oil leak. Later after running the bike for a second time he thought that the leak might be coolant which is what confused me also. After his latest post, I'm thinking it is probably an oil leak in which case I like Ken's suggestion about the oil pressure sender.

Another thing to keep in mind is that Kevin replaced virtually all of his hoses (at least I think he got them all) at the TechSTOC at Steve & MaryAnne's house two years ago. I'm not sure if he replaced the clamps with Belleville clamps or not. He can chime in...

Scooter said:

Here is a picture that Kevin texted to me the other day...



When he initially called me he was reporting an oil leak. Later after running the bike for a second time he thought that the leak might be coolant which is what confused me also. After his latest post, I'm thinking it is probably an oil leak in which case I like Ken's suggestion about the oil pressure sender.

Another thing to keep in mind is that Kevin replaced virtually all of his hoses (at least I think he got them all) at the TechSTOC at Steve & MaryAnne's house two years ago. I'm not sure if he replaced the clamps with Belleville clamps or not. He can chime in...

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That looks like some coolant that has collected a lot of road grime which can look like oil. Pull the throttle bodies off and take a look and see where the leak is.

970mike said:

That looks like some coolant that has collected a lot of road grime which can look like oil.

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Must agree. If there's green down there, it's coolant.

--Mark

Guys today it was OIL. it had me consused yesterday. I know the difference between oil and coolant. Lasr easy check is the pressure switch. Hopefully Sunday.

It could also be the mechanical and oil seal behind the water pump that failed. Do you feel any knocking in the grips or strange noise coming from the waterpump?

Igofar said:

It could also be the mechanical and oil seal behind the water pump that failed. Do you feel any knocking in the grips or strange noise coming from the waterpump?

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That should still come out the round hole I believe. Anything from the square hole is up higher.

What does the oil look and smell like? If the gasket or seal behind the front cover gave up the ghost it could be following the cover seam down and appearing like a leak up in the V area?
I'm hoping its just something as simple as the switch seal for his sake.

Igofar said:

It could also be the mechanical and oil seal behind the water pump that failed. Do you feel any knocking in the grips or strange noise coming from the waterpump?

Click to expand...

If the seals fail oil can flow into the water pump galley and contaminate the coolant only. Where the oil is comming out of leads to the drain hole from the Vee.
There is no vibration or unusual sounds. Have a new pressure switch on its way.
I am hosting WiSTOC at the moment so it will be Sunday before I can get at the next step of removing that switch with the hope of seeing oil where it does not belong.

Perhaps you did see some coolant Kevin in addition to oil--small coolant leaks when cold (even on a well maintained bike) exist on most bikes and are acceptable.

The core concern is oil leak. Possible oil leaks in the vee can be via/through the following:

• Alternator oil seal
• Oil pressure switch threads
• Right cam chain tensioner release (3 bolts on/thru it)
• Block casting plug (called 'mystery plug') above
• Front crankcase cover gasket
• Breather tube leak (the tube that connects to the underside of the air cleaner housing from the left valve cover)
• Cylinder head cover gasket (left or right)
• Cracked cylinder head casting (left or right)
• Cylinder head gasket (left or right)
• Cracked block casting
• Water pump seal failure along with a water pump gasket failure (<< very unlikely ... the oil would be mocha-foamy brown in the oil level sight window)

You should be able to see the source of the leak by pulling the air cleaner housing off and looking under the throttle bodies using a small mirror and flashlight (it will still run and you've a chance to see the oil stream being produced). If the source isn't obvious at that point, you may need to pull the throttle bodies too (obviously you won't be able to run it at that point).

How much oil is it losing (have you had to add any)?

Let us know what you find...