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Discussion Starter #1
This is driving me crazy: I've been having a small coolant loss in my bike that takes the coolant from max to min in about 700-800 miles. I've tripled check every single hose but can't find it. Even when letting the engine at max temp with the fans cycling on and off a few times. Nothing...

So now I need to take it to the next level. Where would you suggest starting from:

1) pressure test to system and see if I can force the leak somewhere

2) get an oil sample analyzed and see if the leak is somewhere internal

It's a 2006 999S: any known weak point in the cooling system?
 

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The weak point, coolant reservoir bursts on the right side where the hose up from radiator connects.

Pressure test is easiest.

If it's getting into the cylinders through the head gasket there should be enough coolant in the cylinders when you start the bike, after a pressure test, that you should have white smoke for a few seconds.

If it's getting into the case just drain the oil into a clean basin so as to reuse it. If there is water in there the water will come out first. If there isn't that much water you will still be able see some in the oil just by looking at it.

Is your coolant still clean?
 

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Discussion Starter #3
The weak point, coolant reservoir bursts on the right side where the hose up from radiator connects.

Pressure test is easiest.

If it's getting into the cylinders through the head gasket there should be enough coolant in the cylinders when you start the bike, after a pressure test, that you should have white smoke for a few seconds.

If it's getting into the case just drain the oil into a clean basin so as to reuse it. If there is water in there the water will come out first. If there isn't that much water you will still be able see some in the oil just by looking at it.

Is your coolant still clean?
Coolant is still perfectly clean: I flushed it just recently and it's still perfect. I highly doubt is head gasket: I'm saying just because there is no bubbling in the radiator or steam from the exhaust and as I mentioned, coolant is clean.

Is there a particular adapter to do the pressure test or people just mickey mouse something?

I didn't know the reservoir on the 999 has a history of bursting/leaking but I guess that gives me a reason to get rid of it. It was in the plans since at some point I want to get some larger runners.

I guess I start with that before getting into the pressure testing...
 

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Have you checked to see if the pressure relief valve in the cap on the coolant reservoir isn't just sending the missing coolant to the overflow catch tank that's mounted between the cylinders? The relief valve may be lifting at too low a pressure.
 

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This is driving me crazy: I've been having a small coolant loss in my bike that takes the coolant from max to min in about 700-800 miles. I've tripled check every single hose but can't find it. Even when letting the engine at max temp with the fans cycling on and off a few times. Nothing...

So now I need to take it to the next level. Where would you suggest starting from:

1) pressure test to system and see if I can force the leak somewhere

2) get an oil sample analyzed and see if the leak is somewhere internal

It's a 2006 999S: any known weak point in the cooling system?
I don't know anything about the 999's having upper expansion tank issues like with the 748-998's. I would say the coolant fill cap may be your weakest point in the system as it's designed to fail at a certain pressure.

If that doesn't solve it just add some UV solution to the coolant, go do some hard riding until you think some has leaked, then search for it with a black light.
 

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I don't know anything about the 999's having upper expansion tank issues like with the 748-998's. I would say the coolant fill cap may be your weakest point in the system as it's designed to fail at a certain pressure.

If that doesn't solve it just add some UV solution to the coolant, go do some hard riding until you think some has leaked, then search for it with a black light.
my mistake. i read 996s
 

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Discussion Starter #13
Problem found: it was the water pump seal... I'll post some pix tomorrow: now it's way past my bed time
 

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It may be leaking past the Head Gasket. I am in the process of having my Horizontal Head and Cylinder resurfaced. It has failed twice; first time was obvious; white smoke. Second was not too obvious until I noticed coolant leaking through the exhaust. Up until this time, I also was noticing my coolant level fall and was uncertain WTF was going on. Have the the coolant system pressure tested, or a compression test for sure, then you will know.
 

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Discussion Starter #17
As said, head gasket is fine. It's the mechanical seal on the water pump.

Sent from my Nexus One
 

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Discussion Starter #19
Today was just cleaning and prepping for the reassemble while I wait to get a minute of daytime to go pick up the seals for the dealer.


Since I was in that general area (and I hate saying that cuz it means more money...) I ended up replacing the hoses as well: the front one in particular they didn't look to good. I just pulled the trigger on the Samco kit since on my monster it definitely gave me 5 extra HP and since on this one I got the blue ones it's probably gonna be a tad more.
 

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While you have the case off I would highly reccommend removing the starter motor so you can pull the end cap off and at least clean the armature. If you have time find the cheap $50 rebuild kit that has new brushes, bearing and o-ring seals. cleaning up the starter marks a world of difference in keeping the 999 turning over crisply. While your at I would also do the starter sprang.
 
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