Coolant system problem.

S

Scott71

Registered
Hi all hope you can help!!!

I went out for a ride Gen 2, i did around 100 miles all was good. When i pulled up on to drive i noticed coolant seeping from under bike, the bike was running fine not overheating according to temp gauge and no spluttering.

I removed fairing and found expansion tank full and coolant seeping from overflow pipe on tank, after bike had cooled i took radiator cap off and radiator is empty.

Do you think this is a thermostat problem, water pump or else were. All advice is appreciated.

Scott
 
Berlin Germany said:
@Scott71

sorry but to me the head gasket is massively under suspect

the exp. tank was really full?

make at first a pressure loss test to find out if the gasket is worn and the air blows somewhere into cooling system.

and don´t start the engine any more before that test please.
Click to expand...
If the headgasket was the issue wouldn't he have gum residue on the oil fill plug? I forgot to ask if he checked the fill plug.
 
TallTom said:
He could have a HG leak that doesn't involve the oil passages. He could just be steam cleaning a cylinder or 2. But the not overheating part doesn't add up. An empty radiator should be showing up on my gauge!
Click to expand...
So just a minor head gasket leak then....

I guess I've never come across one of those before..

Any head gasket leak I've ever seen personally involved the oil and coolant blending together.
 
Bumblebee said:
So just a minor head gasket leak then....

I guess I've never come across one of those before..

Any head gasket leak I've ever seen personally involved the oil and coolant blending together.
Click to expand...
I've seen on rare occasions a failed HG that blows out to the exterior of the head. It can get mistaken for an exhaust leak or valve cover gasket oil leak. I don't know if it's really a gasket that fails, so much as a head that warps and the gaskets are just collateral failures.
 
@HayaWakened

if the exp.-tank is full till shortly under the rubber plug at its top,
the HG is worn and you need a new one.
the exp.-gases of the engine blow into the water system and pump it up ==> water/the coolant "flees" and "goes" to its tank.

@ZeePopo
there never "chocolate" will (can) be found at the oil plug (like at cars, trucks etc.).

techn. said :
there are no such cold surfaces / parts at a bikes engine where "steam" can condensate and mix with the oil to "light chocolate cream" like at cars, trucks etc. where the valve covers usually are made of "metal" and the plug area is the "coldest" area there.
in new/newer cars, i know e.g. from mercedes, these covers are made of plastics to avoid the condesation (a bit)

at least I've never seen it at bike engines (busas), and neither has my brother, and together (in sum) we've probably replaced around 40 busa head gaskets (or even more) in the last 10 years or so - especially on the gen1s and not yet at all at gen2s.
 
Last edited:
Hi all,

There is no milky residue around oil filler cap as someone mentioned and also oil is normal colour through sight glass and no drop or rise in oil level.

I tested the thermostat it didn’t start to open straight away at 82c took a few degrees more and didn’t open as much as specified in service manual at most only 6mm, I have ordered a new thermostat and will try this I will get back to you on the results.
 
@Scott71
I'm late to the party here, but a few questions I have listed below, have not been asked or even considered . . . these are THE BASICS.
1) Has the Radiator cap been pressure tested? If the cap has low spring pressure, it will allow the coolant to flow freely past the rubber seal and fill/overflow the expansion bottle, in turn emptying the radiator and engine of it's coolant.
2)Has the electric fan operation been tested? On and off, switched by the thermo switch? (Depending on weather temps and traffic/speed conditions,) If the fan doesn't run this will cause overheating and push the coolant out of the radiator.
3) Has the radiator been tested for blockage percentage? Has it been pressure tested for leakage/cracks?
If the radiator is blocked or even partially blocked, the system could/will overheat and push the coolant past the spring seat of the rad cap and empty the coolant from the radiator.
4) Also the thermostat needs checking for correct operation (yes I know he has checked it, but the previous 3 checks must be done first before assuming it's just a bad thermostat)

These are the basics to look at BEFORE jumping to conclusions about the head gasket or cracked head/cylinder lining.
Now after the basic checks have been made and all in order, it's time to check for leaking head gasket . . . pressurize the cooling system with 15psi.. is the pressure dropping or staying constant?
Also, run the engine up to normal temp with the cooling system bled (no air in system) and look for bubbles coming up to the rad filler neck.

There are two types of bubbles . .
1) Combustion pressure bubbles caused by a breach in the head gasket seal between combustion chamber and the water jacket.
2) Bubbles created by boiling the coolant.

If the bubbles appear BEFORE the coolant temp reaches 220F (boiling temp) it's definitely a head gasket issue
There is also another way to verify head gasket leaks . . the Tee Kay Head Check.
wbtools.com.au

Tee-Kay Head Check Combustion Leak Detector

wbtools.com.au wbtools.com.au
 
Kiwi Rider said:
@Scott71
I'm late to the party here, but a few questions I have listed below, have not been asked or even considered . . . these are THE BASICS.
1) Has the Radiator cap been pressure tested? If the cap has low spring pressure, it will allow the coolant to flow freely past the rubber seal and fill/overflow the expansion bottle, in turn emptying the radiator and engine of it's coolant.
2)Has the electric fan operation been tested? On and off, switched by the thermo switch? (Depending on weather temps and traffic/speed conditions,) If the fan doesn't run this will cause overheating and push the coolant out of the radiator.
3) Has the radiator been tested for blockage percentage? Has it been pressure tested for leakage/cracks?
If the radiator is blocked or even partially blocked, the system could/will overheat and push the coolant past the spring seat of the rad cap and empty the coolant from the radiator.
4) Also the thermostat needs checking for correct operation (yes I know he has checked it, but the previous 3 checks must be done first before assuming it's just a bad thermostat)

These are the basics to look at BEFORE jumping to conclusions about the head gasket or cracked head/cylinder lining.
Now after the basic checks have been made and all in order, it's time to check for leaking head gasket . . . pressurize the cooling system with 15psi.. is the pressure dropping or staying constant?
Also, run the engine up to normal temp with the cooling system bled (no air in system) and look for bubbles coming up to the rad filler neck.

There are two types of bubbles . .
1) Combustion pressure bubbles caused by a breach in the head gasket seal between combustion chamber and the water jacket.
2) Bubbles created by boiling the coolant.

If the bubbles appear BEFORE the coolant temp reaches 220F (boiling temp) it's definitely a head gasket issue
There is also another way to verify head gasket leaks . . the Tee Kay Head Check.
wbtools.com.au

Tee-Kay Head Check Combustion Leak Detector

wbtools.com.au wbtools.com.au
Click to expand...
Hi,

I have also ordered a combustion leak tester to test this, the electric fan is operating as should be, not checked radiator cap or radiator but all hoses are clear of blockages.

Will let you know results from thermostat changes and combustion leak test when they both arrive.

Thanks for the advice all.
 
Bumblebee said:
So just a minor head gasket leak then....

I guess I've never come across one of those before..

Any head gasket leak I've ever seen personally involved the oil and coolant blending together.
Click to expand...
Bill, I've seen many blown head gasket issues (cars) and most did not mix oil and coolant . . . just remember the combustion pressure is enormous compared to cooling system pressure (15psi or less) and will always pressurize the cooling system rather than coolant flowing into the combustion chamber.
I have only seen on two occasions the coolant getting blown out the exhaust (H/G was utterly blown to bits) and mixing of oil and coolant is common also.
 
Kiwi Rider said:
Bill, I've seen many blown head gasket issues (cars) and most did not mix oil and coolant . . . just remember the combustion pressure is enormous compared to cooling system pressure (15psi or less) and will always pressurize the cooling system rather than coolant flowing into the combustion chamber.
I have only seen on two occasions the coolant getting blown out the exhaust (H/G was utterly blown to bits) and mixing of oil and coolant is common also.
Click to expand...
Most of my head gasket leaks were related to V-8 engines...never had one go on a bike or small engine before.
 
Bumblebee said:
Most of my head gasket leaks were related to V-8 engines...never had one go on a bike or small engine before.
Click to expand...

hi bee :)

unfortunately, your experiences do not quite match the gen1 (´99 - ´07).

this model has a recurring problem with leaking head gaskets (as I said elsewhere, my brother and me certainly must have had 30 or more cases of this type)

the problem is, as far as I/we can judge, grounded in several main things:
1. when replacing the coolant, no meticulous attention is paid to ensuring that the cooler is filled to the brim and free of air bubbles.
2. the switch for the fan is located (top left in the radiator) in a very unfortunate place - the engine runs the risk of overheating and the head gasket breaks / blows through into the coolant
3. one single fan doesn't seem to be enough, especially at higher outside temperatures and the number of individual, horizontal, cooling fins also seems to be too few ==> the gen 2 has 2 fans and, i think, 3 or 4 more horizontal fins as a countermeasure . (but with moving the switch to RH this problem is nearly 99% solved - see the link in the next paragraph)

to point 2. (above), we (bros & me) generally recommend moving the fan switch to the rh side in the water hose more or less directly at the head by THE t-piece. (how to? see here my page)
this permanently reduces the water temperature in the system by about 5-10°C and the head gasket THEN feels like it lasts forever.

again to point 2. (above) : a 2nd way to lower the prob of over heating a bit
buy ´n replace the hayabusa fan switch by another one which switches at 95°C and no more at 105°C ;)
THIS (M18x1.5 outside thread) switch is e.g. used in the suzuki scooters and has the art.-no. 17680-50F10
 
Last edited:
Berlin Germany said:
hi bee :)

unfortunately, your experiences do not quite match the gen1 (´99 - ´07).

this model has a recurring problem with leaking head gaskets (as I said elsewhere, my brother and me certainly must have had 30 or more cases of this type)
Click to expand...
Agreed,

Definitely not the same experience...never had a head gasket go in any of my small engines (and I've had more than a few water cooled small engines from snowmobiles to diesel garden tractors).
 
Hi all,

Thanks for all the ideas a quick update replaced thermostat no change in fault, bleed cooling system and burped box change in fault, did compression leak test x3 all came back ok.

Replaced radiator cap drained coolant and replaced with new 250 miles down and all good now so looks as thou faulty radiator cap.

Thanks for the advice.

Scott
 
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