1993 Overheating...

I have a 1993 VFR750F and am having a problem with overheating. Seems to be okay when Im on the highway but riding through the city with some traffic causes it to slowly overheat.

Symptoms:
- Temperature guage slowly increases.
- Never hits the red as my coolant resevoir starts letting coolant out via the overflow and this caused me to pull over.
- Coolant in the resevoir is high and boiling.


I dont recall the bike doing this when I bought it last November but I also didn't ride it under these conditions (riding was limited at the end of the season). Mechanic just recently did a valve adjustment to the bike and my rad cap was just replaced (thinking that may be the cause of the problem).

When my mechanic was putting my side fairing back on yesterday he noticed the neck (of the radiator by the cap) was bent. Not sure if this is stock or as a result of damage from a previous owner, etc. I suspect either this or the Thermostat but am looking for suggestions, advice, information, etc.

Looking to bring the bike back to my Mechanic tomorrow.

Derec

 

When its hot, does the fan come on? You might have a bad temp switch. If the rad neck is bent, there might be other damage to the rad. Whens the last time the coolant was changed?

FWIW, VFRs tend to run hot, especially in slow-moving situations (city). The fan on mine comes on a lot when I am rolling through town.

 

Does a '93 have a fan?
(I am sorry if that sounds like a really dumb question)

When I ride the bike to my Mechanic tomorrow I will have to take note of the fan (granted there is one) cause at the moment I don't know (never paid attention for that). As for the coolant...it was changed when the valve adjustment was done. They had to take off the radiator.

Derec

 

Ok...I totally answered my own question and there is a fan on the 1993.

I figure it will be one of four things:
1. Rad cap (unlikely as I am already on number 2)
2. Thermostat
3. Temp swtich for the Fan
4. That bent neck on the Radiator letting air into the system


The coolant level in my resevior gets very high when it is overheating...I am not sure if that is normal or what it indicates. When the bike cools down the levels go back to normal.

Derec

 

Yep, thats normal. The reservoir is officially called a Recovery Tank; as the engine heats up, the coolant moves into it. When it cools, it moves back.

You def have a fan; it's a H2O-cooled engine. Make sure you have the correct rad cap (and that its not worn), make sure the fan is coming on when it's hot (it's pretty loud so you shouldn't have any prob hearing it). I'd start there if it were me, then move on to the thermostat; you can check to make sure it is opening at the correct temp by heating it on your stove in a pan of water and checking it with a meat thermometer. I'd also have your mech look the rad over and make sure the neck isn't bent as that may be affecting whether the cap works correctly.

 

Not having the fan kick on has been your main problem.

the rad-mounted temperature switch is a VERY common failure item on Hondas, but here's a chance your mechanic forgot to plug the fan into wiring after rad removal.....

 

Good suggestions. An easy way to determine this is find the fan switch on the rad and unplug it. Turn your key on and if it's a two wire coupler short 'em with a paper clip, if it's one wire ground it and your fan should run. If it does the fan switch is bad...if it doesn't, check the motor coupler to make sure it's plugged in. If it is...you should have positive battery power there...if you don't, locate and check the fan motor fuse.

 

Well...I took the bike back to my Mechanic and told him what I suspected was causing the problem. A few days later they called me to confirm that the fan had, in fact, not been coming on as I had suggested and that it was now working properly. In the end they didn't charge me for the new Rad Cap they thought was originally causing the problem and I was not charged any labour. I didn't call my Mechanic out on it (I'll let it be their secret) but I suspect they forgot to plug the fan in and found it when they gave everything a closer look.
*shrug*

Either way...I will know Thursday morning if it is still a problem. That is when I will make the run I have overheated on twice (slow moving city traffic).