Fan, radiator, water pump issue 2002 VFR

So being new to VFR's I have found out that they do run hot, but my fan is not kicking on.

I have ground out the fan and it does work, so that is not the issue. With the fairings off I have run the bike up to 230-235F and the top of left side radiator where the thermal switch is doesn't seem like it gets very warm, initially. At around 185F it looked like the thermostat opened because the temp dropped down to about 180 before heading back up. After turning the bike off at 235F it did release coolant into the overflow tank enough to push coolant out the overflow tube. After sitting and cooling a little, on restart the top of the left side radiator was warm to hot to the touch, just not as hot as the bottom of the radiator and definitely not as hot as the right side radiator.

I did top off the radiator and that drained into the overflow tank before start up to the minimum mark before I ran it up to temperature.

I ran it up to 230F 3 times and during that time the fan still didn't kick on.

I am going to try a new radiator cap and leaning towards a new thermal switch to see if that helps but any other suggestions would be appreciated.

Luckystrike

 

Assuming your 6th gen is like my 5th gen... There are 2 wires going to the thermal switch, one from the fan and a ground wire for the radiator which is insulated by the rubber mounting grommets. You can check the wiring by shorting the switch terminal to the radiator body. If the fan comes on, the wiring and fan are OK. When the engine is hot (over 220F), check the voltage at the switch terminal. It should be near 0 V (switch closed). If you think there is an air pocket in the left radiator, park the bike on the side stand, and the air should move to the right side where you can check coolant level with engine cool at the radiator cap. Sounds like you're on the right path to tracking it down.

They do run hot. I'm thinking of installing a thermo switch rated at 85C to bring the fan on earlier. I also added a 120mm x 25mm computer fan behind the right radiator with a switch to turn it on in traffic. It helps, but is not enough to keep the engine cool by itself.

 

Like H3nry said....!
Check the fan first and the switch to make sure they are in working order.
Bases on your statement above seem like the pump is on the way out or the radiator is clog
How old is the fluid and when is the last flush?

 

Sounds exactly like an air pocket as previously stated.

I've never seen3 those temps on my 5th gen & that includes sitting on a sweltering slab in 90 degree weather.

 

Will have to check the switch when it is up to temp. according to PO maintenance log the last coolant change was 1200 miles ago.

 

Yep, what they said. The fan is supposed to come on at 220-221 degrees.

 

Thanks for all the quick replies. Got the issue sorted out and it was a pretty easy fix.

I bought the bike on the condition of getting the cam chain tensioners replaced before I took ownership, they were pretty noisy. Not sure if the PO or the bike shop that did the work got two of the radiator lines mixed up. there is a bypass line off the top of the right radiator and there is also the bypass line to the overflow tank, the lines are very similiar in size, just different clamps. At some point the lines got mixed up. I couldn't figure out why, when adding coolant to the radiator the overflow was filling up. A quick look at exploded view of the system on Partzilla and saw bypass line off the radiator. Took a look and sure enough they got switched.

Put the lines back the way they should be, topped off coolant, 5 min idle up to temp and the fan kicked on at 220F, temp dropped to 210F and the fan kicked off.

Luckystrike

 

Good job!! Now just make sure you use a Honda spec type coolant to keep from messing up the water pump.

 

Yep, silicate free and aluminum safe.

 

Glad it work out without any $$$$ loss :whoo::whoo:

 

All the junk VFR thermoswitches in my trash bin indicate anything over 100C. turns on the fan. Seems semi-unexplzainabled that Honda decided to raise the specs, then ran into higher temps on later gens.