1995 Honda CBR F3, Overheating ...

Absoluteg · 04-23-2008, 12:15 AM

So I've recently noticed that my bike is overheating when I'm stuck in traffic or idling for a long period of time. So far I've replaced the Thermo Sensor (Which tells the gauge when its hot), and Thermostat, also the Fan Switch (When the coolant gets hot the switch grounds the circuit making the fan turn on). The Fan never turns on, even when the temp starts to rise. I'm not sure if thats normal . I will try to clean the radiator as best i can. Any suggestions on what could cause the Bike to overheat and what i could do to resolve the problem.

lanbrown · 04-23-2008, 12:19 AM

How is the radiator cap? Any air in the system? When was the coolant chnaged last? Did you use distilled water?

Absoluteg · 04-23-2008, 12:23 AM

The Radiator cap looks fine (but i did not test it), I did flush the system recently, but unsure of how to purse air in system (if any). I used 50/50 of a pre-mixture.

lanbrown · 04-23-2008, 12:27 AM

Make sure the cap seals properly. You might just replace the cap, the spring could keep the correct pressure from reaching. It could be 13-years old.

Make sure you do this when the engine is cold. To purge air, you need to have the engine running and just squeeze the hoses to dislodge air. Blipping the throttle can help as well.

Absoluteg · 04-23-2008, 12:32 AM

I Appreciate the advice, i will purchase a new cap, and also try the technique of blipping the throttle and squeezing the hosed to dislodge any air.

lanbrown · 04-23-2008, 12:37 AM

A cap should be $10 or so, so it is cheap to try.

Absoluteg · 04-23-2008, 4:04 PM

Its $30 from the dealership, I opted to purchase one from Auto zone for $8. I did make sure it was a 16lb cap. After replacing the cap, I did degrease the radiator. Its still Overheating

!!! I cant think of anything else ...

-G-

lanbrown · 04-23-2008, 6:13 PM

If it was the thermostat, it would be stuck open. I think you have air in it then. Unless the bike is running way too lean.

Absoluteg · 04-24-2008, 12:03 AM

So how else can i bleed the system (Besides what i did previously)?

-G-

lanbrown · 04-25-2008, 12:39 AM

Rock the bike from side to side. Air can be tricky and wants to stick around.

How does the coolant look?

blue1000rr · 04-25-2008, 1:28 AM

is your water pump operating like it's supposed to? also put some Water Weter or Engine Ice in it. makes it run 10-20 degrees cooler. also check the fan motor if it isnt turning on at all. mine turns on at about 202 degrees

Absoluteg · 04-25-2008, 8:56 AM

I've rode the bike a few hundred miles, would that be enough for the bubbles to come loose? I did replace the water pump seal about 2 months ago, the water pump looks good and seems to be working normaly. I've grounded out the fan (It turns on). When i plug it into the fan switch(in the radiator), no matter how hot it gets, the fan never turns on. The coolant was flushed about 2 months ago and looks good. I dont have a digital temp gauge, i have a analog one (which isnt that reliable). I also have some pictures posted, ill post some of the guage.

Absoluteg · 05-13-2008, 2:24 PM

So ill tried the technique of bleeding the air out of the cooling system by:
Removing the radiator cap
Blipped the throttle
Replaced cap after about 1 minute.
Let bike idle till it got to normal operating temperature, then waited a few more minutes to watch the bike overheat again.
Any other ideas ?

avendelrdp · 05-18-2008, 1:59 PM

Check and see if both the inlet and outlet hoses to the radiator and getting hot. If one is not, then your water is not circulating. Could be the pump, or the thermostat. Could be an obstruction in the system.

jordantech02 · 05-19-2008, 1:59 PM

Just wanted to make sure you checked your fuse for the fan circuit because you have not listed this in your diagnostic checks.

SoCal94F2 · 05-23-2008, 5:52 PM

All of the above are good suggestions, but If I had to guess based upon your description, I would say that the ground to your radiator is not connected. Your fan sensor switch is probably doing what it is supposed to by connecting the ground wire to the radiator, but because the radiator is rubber mounted it needs to have the ground wire from the plug attached directly to the radiator metal (usually at the fan mount). Make sure you clean that connection of all paint and such so you get a goo ground.

Worste case scenario, you could always run a wire from ground to the sensor plug - the fan will always be on when the key is on.

Absoluteg · 05-23-2008, 8:15 PM

I did check the routing of the hoses, they are correctly installed. I also check the fuse for the fan circuit and the ground(where radiator is mounted), all are good and working fine. I did ground out the fan so it stays running, the temperature would still climb to hot. The only thing i haven't checked is the actual gauge. The service manual says to ground it out and watch the gauge rise to hot (Would be nice if i knew the resistance). Ill try and get it to the shop to have a technician look at it but that would not be for a few weeks. More suggestions would be appreciated.

-G-

SoCal94F2 · 05-23-2008, 10:17 PM

For the temp sensor next to the fan you only need 3 things to test; a boiling pot of water, a multimeter and a cooking thermometer. Bring a pot of water to 200 degrees using the thermometer, attach leads to sensor and submerge it. Bring the temp of the water up quickly. Resistance should drop move from almost open to almost shorted at around 215 degrees.

Absoluteg · 05-23-2008, 11:46 PM

Thanks for the information, I've replaced that sensor. I was asking how to test the actual gauge. I did read the service manual but it does not show the testing procedures for the gauge.

Absoluteg · 05-31-2008, 3:45 PM

Yesssssaaaaaa !!! So I tried to "burp" the cooling system again. Apparently it worked, my temp got up to just over half then the fan kicked in and brought it back down a bit then the fan shut off (Like it should). So Thanks Again for everyone's support and advise, I appreciate it. Now ill be riding as much as possible.

-G-