Coolant question

[CISE]

I have a 99 I/S with 89K miles on it. There seems to be a cooling system issue.


(All coolant levels checked when cold)

Stars off with good coolant levels, the reservoir tank is at the proper level.

Run the bike for a while (800 miles - one week's driving), and the radiator is down maybe 3 ounces of fluid - and the reservoir is high.

It looks like that when the bike heats up, the expanded coolant goes into the reservoir, but never goes back.

Any ideas?

Thanks in advance!!!
 

[bigdog99]

check the plastic tank breather line to make sure iyts not plugged, you may be sucking air into the filler cap too. was it wet when you put it on? it may not be sealing good.

[Wildman]

Check the integrity of the resevoir line that returns to the radiator cap and it's connection to the radiator cap collar.

[Wildman]

put a piece of card board under it to check for leaks.
It's common to have the inlet and outlet radiator hoses leak due to slightly loose hose clamps

[sandy]

Only 2 things can be wrong. The rad cap is failing and/or the overflow hose has a small hole in it. If the res has more fluid and the rad is down, it's the cap. Buy a new one.

[CISE]

 

Thanks!!!! I will replace teh cap & check lines this weekend!!!

[Ricky-D]

Where the cap attaches is an important place to inspect.

There is a set screw that is intended to keep the cap immobile.

Failure to note the "screw" will result in deforming the mating surfaces and thereby cause the cap to become a failure to operate properly.

Notice the cap has two sealing surfaces.
One seal is to maintain the pressure inside the radiator and motor.
The other seal is to close the system completely and allow the radiator to utilize the fluid recovery operation from the reservoir tank.

The latter sealing is probably where your problem lies.

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