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Discussion Starter · #1 ·
Hey everyone,

I'm opening the engine tomorrow for other issues but I figured I'd ask anyway. My coolant has been sloooowly lowering for the past couple of months.. it's really nothing extreme, like half an inch every couple months. Every now and then, I add a sip to keep it up to the "max" line so I can see how much it's loosing, etc.

Couple weeks ago a friend of mine worked on the bike a bit, did an oil change and when he noticed the coolant was down (it was down about 3/4 inch) so he added some and ended up with 3/4 over the mark. No biggie...

This weekend we did a ~220 miles ride on saturday and against all my expectations, it raised instead of lowering AND I was loosing a bit out of the overflow tube (just drops, nothing extreme).

I have an inline temp gauge on the top hose and never at any point did it go over 200 degrees (it's always been about there at operating, *ahemm*, beating temp).. so I don't think it's overheating...

What do you guys think it could be? Only thing I can see that would get so much out in the overflow would be compressing in the coolant system, but then again, I have no overheating, oil is clean, no coolant smell out the exhaust, no perceived loss of compression, etc.

I'm about to go out and start taking off stuff the bike, I'll report back on the coolant level in the rad.
 

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u know mine has done that also a little bit but one thing ive noticed it doesnt not like a completly full radiator it will just push it out into the resi bottle. so i havent added any coolant at all for awile and just noticed that my resi was empty. i also have not had any overheating issues. but i dont know exactly what my temp is untill i install my vapor system which is on the way. but more than likely if u have a problem i do as well. but i would just keep going if no overheating issues arise.
 

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Discussion Starter · #3 ·
Like I said I need to open it for other reasons so I guess I'll inspect everything when I get to it.. I'll check the water pump and thermostat as well... I'm sure there's something wrong somewhere cause it didn't do that before and it seems to be getting worse.

At first it was just lowering slowly, so I thought it was a bit of it getting out the overflow when doing wheelies... but last ride, the tide turned around, the coolant literally raised up to the top of the bottle and some of it is leaking from the overflow tube right on the ground... not a lot of it, but still...
 

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Discussion Starter · #4 ·
Well I opened her up last night and I can't see any issues. I filled the rad before dropping the coolant to see how much was missing and it was missing about 150-200 milliliters which is about what I have extra in the overflow.

No apparent damage to the head gasket... so I'm a bit confused. Could it be my rad cap that's not holding pressure?
 

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2008 SMX Series Champion HO
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Rad cap is good for 120psi I believe, If it rises above that from overheating it will blow steam out the top and i'm sure you haven't seen that.
 

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Discussion Starter · #6 ·
Rad cap is good for 120psi I believe, If it rises above that from overheating it will blow steam out the top and i'm sure you haven't seen that.
Isn't the rad cap bidirectional, in the sense where it will spew some in the overflow when there is too much pressure and take from it when there is negative pressure? I'm guessing the 120 psi you mention would kick in if the little hose is plugged?

I'm really concerned and confused about why my overflow is filling like that and my rad is emptying... 200 ml isn't a lot though.. and I'm not seeing anything wrong on the temp gauge.. so it's weird.
 

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Correct me if I'm wrong but I've heard a head gasket leak can cause air to get into your cooling system and overflow your radiator into your jug.
 

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From The Stix 2 Da Brix
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Correct me if I'm wrong but I've heard a head gasket leak can cause air to get into your cooling system and overflow your radiator into your jug.
I seen this on many many cars.
 

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Discussion Starter · #9 ·
Correct me if I'm wrong but I've heard a head gasket leak can cause air to get into your cooling system and overflow your radiator into your jug.
Yeah that's what I think it could be. I inspected the head gasket closely last night and couldn't find any signs of compression getting into the coolant area but I guess it can be hard to spot if it's not a major leak.

I'll take the water pump and thermostat off and inspect all of that for any damage or weirdness... and if all checks out I'll have to assume the gasket had an issue. I'm replacing my piston so it's all apart already.
 

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Double check all your lines and the clamps, I got my motor back from a dealer with a loose clamp between the water pump and cylinder, good thing I caught it, I had another line on top of the radiator back off a few mm and took me a bit to catch it. If your not losing any overall net amount of coolant than disregard. Do a compression test and see where you stand.
 

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Discussion Starter · #11 ·
Double check all your lines and the clamps, I got my motor back from a dealer with a loose clamp between the water pump and cylinder, good thing I caught it, I had another line on top of the radiator back off a few mm and took me a bit to catch it. If your not losing any overall net amount of coolant than disregard. Do a compression test and see where you stand.
Alright, I guess there's no clear answer. I'll inspect everything and when I get my new piston I'll close it up and see what happens. I don't seem to be loosing a significant amount of coolant, but I know I'm loosing a bit of it because every time I stop there is a coolant smell. It's coming from that baffle under the tank and it's very small amounts (drops basically).

Also when I opened it it confirmed my suspicion, the rings were blowing oil. I'm guessing some compression was lost in the base as well.. I don't see how this could affect coolant but might as well mention it.
 

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I had a top end goin bad years ago and I had the piston slap, rings goin, burnin oil and coolant lol....you gotta keep that top end fresh and stay on top of oil changes and clean oiled air filters to make it last. Let your quad run and set a bowl under the water pump drain hose, see if any water comes out of there too, does your oil have any coolant in it ?
 

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Discussion Starter · #13 ·
I had a top end goin bad years ago and I had the piston slap, rings goin, burnin oil and coolant lol....you gotta keep that top end fresh and stay on top of oil changes and clean oiled air filters to make it last. Let your quad run and set a bowl under the water pump drain hose, see if any water comes out of there too, does your oil have any coolant in it ?
Oil didn't have water in it. As for the top end I've maintained it very well since I've had it. The ring problem was there for quite some time, but it wasn't bad at all at first so I figured I'd wait and see how long I can keep it up. Now is the time.. but it doesn't really explain the coolant issue unless I'm missing something.

Btw can't have it run right now, the head, piston and cylinders are in a box in my truck :)
 

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So you've torn it down already ? Just prep the mating surfaces for a good gasket seal and I'm sure she will be fine, check the decking on the head for a good flat surface, good luck. Are you gonna throw a new piston and rings in it ? Take the opportunity to have a shop clean your exhaust ports out too ;)
 

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Discussion Starter · #15 ·
Yeah I got a 11.5 tqs piston ordered and I'll make sure the install is proper.. the rings I have now were custom made by TopSeal to fix the KDS piston issue but apparently either they f-ed up or I did :) It was all cheap enough that it's no biggie...
 
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