Gsxr 750 dumped coolant during a ride

[PaleHorse]

I picked this bike up a few months ago and have been riding it constantly. I took it out today, rode up old san Jose, into Saratoga and stopped at 9 and skyline. I turned the bike off and it dumped a big spot of cool and on the ground. I couldnt tell where it was coming from at the time. Started the bike back up and it didn't leak anymore.

I limped it back home watching the temp gauge and all it ran around 190-200 degrees. Put it up on stands in the garage, pulled the fairings and dont see anywhere it could be leaking from and it wont do it again. The coolant was a little low and I topped it off. Still wont do it.

Any idea what the cause could be? Temps were normal leading up to it leaking.

 

[Busy Little Shop]

Possible boil over from the catch tank... proper order of items to trouble shoot are:

1)Faulty radiator cap... system should hold 1.1 pressure ratio...
2)Insufficient coolant...
3)Passages blocked in the radiator, hose or water jacket...
4)Air in the system...
5)Thermostat stuck closed...
6)Faulty temp meter or thermo sensor...
7)Faulty fan...
8)Faulty fan switch...

 

[GPzPop]

yes, i would check the rad fan for correct operation.
i ended up putting a manual switch on my zzr, although new thermostats are not too expensive

also, the catch tank can get brittle, crack and leak, with age

 

[mototireguy]

Possible boil over from the catch tank... proper order of items to trouble shoot are:

1)Faulty radiator cap... system should hold 1.1 pressure ratio... 2)Insufficient coolant... 3)Passages blocked in the radiator, hose or water jacket...
4)Air in the system... 5)Thermostat stuck closed... 6)Faulty temp meter or thermo sensor... 7)Faulty fan... 8)Faulty fan switch...

+1 start with radiator cap. If rubber brittle can not hold pressure and burp into the overflow and then overflow overflows.

 

[PaleHorse]

I started the bike on stands with the fairings off and let it come up to temp again the. When the bike hits 219 degrees the fan kicks on.

A new radiator cap was only a few bucks so I ordered a replacement. It appears that everything is functioning as it should. Checked all hose connections as well and they were dry.

Still really confused as to why this happened. Nothing like walking over to the bike and having a big puddle under it.

 

[Alan_Hepburn]

Still really confused as to why this happened. Nothing like walking over to the bike and having a big puddle under it.

Did you notice someone standing close by, with a s**t-eating grin on their face?

 

[ST Guy]

My vote is air in the main cooling system.

One major cause of this that the majority of mechanics miss is the integrity of the overflow system, most especially the hose (and its connections) that goes to the overflow bottle. Not only must it not leak coolant, it must not leak air when under a vacuum. If there is any vacuum leak, when the engine cools down after use it will suck air into the main cooling system instead of coolant. After enough cycles of this you end up with too much air in the system and bad things start happening.

Even if the hose looks good, replace it. Also thoroughly clean the fittings the hose slips over at each end. Sometimes the hose will go straight to the bottom of the tank so you only have that one fitting just under the pressure cap. That on often gets corroded, making it difficult to get a good seal. I've had to smooth it up before with some fine sandpaper. I also use some wheel bearing grease to assist with the seal. And don't use screw clamps, use the little wire spring clamps.

I can take a bike with a perfect cooling system, put a tiny leak in the overflow hose that will only leak air, and end up with your exact symptoms.

 

[ST Guy]

FYI, cooling system pressure caps have three sals, two of which are valves.

The first seal is the main seal to the neck it attaches to. It's a static seal and depends on the rubber itself for the seal

The second seal is the one that has the big spring behind it. This is the one that allow pressure to build in the main cooling system to raise the boiling point of the coolant. If the pressure builds up to high, the spring yields and allows some coolant to go to the overflow tank.

The third seal is a small one with a light spring. It's located on the bottom of the second seal. When the engine is running, pressure keeps it closed. When the engine cools and a vacuum is created, it opens and coolant flows back into the engine....assuming there are no vacuum leaks between the seal and the coolant in the overflow bottle.

FYI, the overflow tube should always have coolant in it.

 

[PaleHorse]

Did you notice someone standing close by, with a s**t-eating grin on their face?

I wish. That would make this much easier.

Looking at the bike closer today I can see a small amount of residue on the fairing where the small hose from the overflow / reserve tank stops.

What would cause the overflow to "overflow" and dump the coolant?

Edit: the overflow tank is about 1/3 full with the bike sitting level and cold.

 

[Tom G]

I had problems with a car where the head gasket has a small leak under high engine load. It will push the water into the overflow and eventually leak out. The engine has high miles and needs to be replaced. Or a head gasket replaced.

 

[ST Guy]

I wish. That would make this much easier.

Looking at the bike closer today I can see a small amount of residue on the fairing where the small hose from the overflow / reserve tank stops.

What would cause the overflow to "overflow" and dump the coolant?

Edit: the overflow tank is about 1/3 full with the bike sitting level and cold.

Often, the cause is air in the main part of the cooling system. When pressure builds high enough, the pressure cap allows the air to escape. And, because air is compressible and coolant is not, there's a large volume of air that escapes and makes it's way down the overflow tube to the overflow bottle and that air then blows coolant out the bottle which has it's own vent. If it was coolant getting released from the main part of the cooling system, the volume of the coolant released is relatively small. But when it's air that is released, it expands much more than the coolant would and it's enough to blow coolant out the overflow bottle.

Check your overflow system.

 

[PaleHorse]

Often, the cause is air in the main part of the cooling system. When pressure builds high enough, the pressure cap allows the air to escape. And, because air is compressible and coolant is not, there's a large volume of air that escapes and makes it's way down the overflow tube to the overflow bottle and that air then blows coolant out the bottle which has it's own vent. If it was coolant getting released from the main part of the cooling system, the volume of the coolant released is relatively small. But when it's air that is released, it expands much more than the coolant would and it's enough to blow coolant out the overflow bottle.

Check your overflow system.

Thanks! I have a new oem cap on it's way. In the next few days, I'll drain the system including the overflow and replace the coolant with new and make sure I get all of the air out of the main system.

 

[rise above]

pray its the cap/thermostat.....not the head gasket is theres a oily sheen in overflow tank its the head gasket

 

[ST Guy]

And replace he overflow tube anyway. Feed the new one in as you slowly pull the old one out. That way there's no doubt about the routing. Clean the fittings the hose goes onto. Use a little wheel bearing grease to assure a seal at both ends. And use the spring clips, not screw clamps. Good luck!

 

[Hooli]

GSXR's usually have an air bleed screw somewhere, either on the water pump or thermostat housing.

 

[PaleHorse]

GSXR's usually have an air bleed screw somewhere, either on the water pump or thermostat housing.

I just got a Clymer manual for the bike in the mail last night and you are correct. There is a bleed screw on the thermostat housing.

Also, the manual says to not lubricate the hoses as they could slip off and to only use screw type hose clamps.

 

[ST Guy]

I just got a Clymer manual for the bike in the mail last night and you are correct. There is a bleed screw on the thermostat housing.

Also, the manual says to not lubricate the hoses as they could slip off and to only use screw type hose clamps.

For the main cooling system hoses, yes, no lube or spring clamps. For the overflow hose it's fine. It doesn't see any pressure and all it needs is a spring clamp. Screw clamps can't compensate for hose material creep and eventually you end up with leaks. A spring clamp can compensate.

 

[Alan_Hepburn]

Need hose clamps and don't know which type is better? Take a look at this tool - saw it demonstrated recently and it looks pretty impressive...

 

[295566]

Need hose clamps and don't know which type is better? Take a look at this tool - saw it demonstrated recently and it looks pretty impressive...

Looks sweet, but three thoughts: 1) holy balls that's expensive 2) that looks like a PITA to do in tight spaces, like for radiator hoses 3) that looks like a PITA to remove, and of course they're single use

 

[PaleHorse]

pray its the cap/thermostat.....not the head gasket is theres a oily sheen in overflow tank its the head gasket

Nope... drained the coolant and the oil out of her tonight and everything is clean. No cross contamination. :thumbup