Radiator / head gasket blown?

[GavGav]

Hey all, hope someone can put my mind to rest.

My 07 FSR has a habit of loosing coolant.
I suspect it is the head gasket.

Symptoms:

• Looses fluid. (200mm aprox per ride)
• System stays presurised for a few days, even when cooled down to stone cold.
• The fluid in reservoir behind the head-stem goes white frothy when you rev the bike. But it does not stay frothy when it quickly settles (eg No oil in there)

I have had the thermo fan fitted as I thought the fluid was disappearing down the overflow through the radiator cap. (KTM one fitted)

Questions for you fellow FSE-FSR riders:

1. Does everyones fluid go frothy when you rev the engine? (cooling fluid that is! )
2. Anyone fitted a boil over reservoir LIKE THIS to catch the lost fluid and will it return to the radiator when cool?
3. Can a gaskit be blown where it forces air into the cooling system but not loose it all the other way?

I should probably take some video to help explain it.

My back pack is getting a bit heavy now with the 1.25L of reserve fuel, 600mm of spare coolant, 2L of camelpak and tools!

Any help appreciated.

[GavGav]

Anyone got any ideas?

Anyone?

[iajim]

I don't own, nor have even worked on an FSE 450, My experience w/other four strokes is that you probably do have a leaking gasket. If it is a very small leak the coolant is being burned/ consumed/ turned into steam leaving the engine. When the engine is running at idle there could be a "sweet anti-freeze" odor. Check the exhaust , determine if there is coolant residue coming thru the muffler. You could have a small amount leaking into the engine, but not enough to contaminate the oil. What is puzzling is the radiator remaining pressurized even when it is "overnite" cold. I would do a little more checking before you tear everything apart. One other wild guess, make sure the radiators are flushed and clean, no sludge in the bottom to impede water flow to the pump. Let us know what you find out. Jim

[jostby]

My 07 FSR has a habit of loosing coolant.
I suspect it is the head gasket.

Symptoms:
Looses fluid. (200mm aprox per ride)
System stays presurised for a few days, even when cooled down to stone cold.
The fluid in reservoir behind the head-stem goes white frothy when you rev the bike. But it does not stay frothy when it quickly settles (eg No oil in there)

Can a gaskit be blown where it forces air into the cooling system but not loose it all the other way?

Yes, rare but not unheard of. Compression pressure is higher than the coolant pressure. It is possible that a weak gasket or o-ring will allow preesure to pass one direction but not the other (radiator pressure 14psi +/- vs. compression at 175psi +/-). Cylinder pressure may pressurize the cooling system (radiator) but if that is the case it usually will also blow the coolant out the overflow because the radiator cap is not strong enough to contain it. But if you really are seeing bubbles when reving the engine I think you are seeing combustion pressure that is leaking through. I hope you will post a follow-up when you find the cause.