overheating!!!!

Hi

I got my 1985 VF500F about 6 months ago and i've had a overheating problem.
now im not a very good mechanic but im learning as i go.
normally when im ridding on the highway its pritty goot, it sits on about 1/3 on the tem gauge.
but once i get into town it gets very hot and the fan comes on. the tem gauge goes right up to the red.
also when it gets hot it revs up, at idal it sits on about 4-5000 rpm.

i've flushed out the engine and the raidator, they seemed clean. i took the thermalstat out and checked it.
that was fine and ran it a bit without the thermalstat and it still ran hot.

im not sure what else to check so if anyone has any advice for me that would be nice, thanks.

[image: View Post]Talon, on 02 December 2009 - 01:42 AM, said:

Hi

I got my 1985 VF500F about 6 months ago and i've had a overheating problem.
now im not a very good mechanic but im learning as i go.
normally when im ridding on the highway its pritty goot, it sits on about 1/3 on the tem gauge.
but once i get into town it gets very hot and the fan comes on. the tem gauge goes right up to the red.
also when it gets hot it revs up, at idal it sits on about 4-5000 rpm.

i've flushed out the engine and the raidator, they seemed clean. i took the thermalstat out and checked it.
that was fine and ran it a bit without the thermalstat and it still ran hot.

im not sure what else to check so if anyone has any advice for me that would be nice, thanks.

Did you bleed the air from the cooling system after filling? There is a bleed screw on the thermostat housing.

What condition is the front of the rad in? Are there a lot of bent fins?

Drain the coolant and take the water pump cover off. Is it blocked with sludge?

Failing those, remove the pump (which will drain some engine oil) and check the drive shaft tabs aren't broken.

In addition to what has been mentioned you can also try "burping" your system to remove excess air. This may seem like a stupid question but you have checked the coolant level in the radiator itself and not just the level in the overflow tank??

Regards,
Rollin

[image: View Post]rhubarb, on 02 December 2009 - 05:03 AM, said:

[image: View Post]Talon, on 02 December 2009 - 01:42 AM, said:

Hi

I got my 1985 VF500F about 6 months ago and i've had a overheating problem.
now im not a very good mechanic but im learning as i go.
normally when im ridding on the highway its pritty goot, it sits on about 1/3 on the tem gauge.
but once i get into town it gets very hot and the fan comes on. the tem gauge goes right up to the red.
also when it gets hot it revs up, at idal it sits on about 4-5000 rpm.

i've flushed out the engine and the raidator, they seemed clean. i took the thermalstat out and checked it.
that was fine and ran it a bit without the thermalstat and it still ran hot.

im not sure what else to check so if anyone has any advice for me that would be nice, thanks.

Did you bleed the air from the cooling system after filling? There is a bleed screw on the thermostat housing.

What condition is the front of the rad in? Are there a lot of bent fins?

Drain the coolant and take the water pump cover off. Is it blocked with sludge?

Failing those, remove the pump (which will drain some engine oil) and check the drive shaft tabs aren't broken.


thanks for that advice.
i did bleeed the air but that didn't seem to make ant difference.

the front of the red is pretty good. there is a few bent fins but not many.

i had a look at the water pump and there was no sludge.
and i took it off and it all seems fine. the actual pump is a bit stiff and rough but it still spins.

and what does burping it mean? how do you do that?

Burping the system is another way of getting trapped air out. You would fill the radiator to the top with 50/50 mix of coolant/water and then also fill the overflow bottle to the correct level. You then leave the radiator cap off and turn on the engine, rev it up a few times and let it run until you see the coolant level drop or hear a large air bubble come to the top of the radiator opening. After the air has been expelled you simply top the radiator off again and put the cap back on. How exactly did you check the thermostat? Did you put it into boiling water to see if it opened properly?

Regards,
Rollin

with the idle going up so high (4-5 grand) when hot, you may have an air/vacuum leak. that would explain the overheating (extra air=lean=running hot) and also the high idle.

[image: View Post]CandyRedRC46, on 02 December 2009 - 09:50 PM, said:

with the idle going up so high (4-5 grand) when hot, you may have an air/vacuum leak. that would explain the overheating (extra air=lean=running hot) and also the high idle.


well i have tried burping it then. yes, i put the termalstat in boiling water and it opened up.

do you check the spark plugs to see if its running to lean?

how would you fix or check an air/vacum leak?

would that be by re-tuning the carbs?

[image: View Post]Talon, on 03 December 2009 - 03:42 PM, said:

how would you fix or check an air/vacum leak?

Check the condition of the carburetor boots and clamps. Loose clamps or cracked boots can cause an air leak.

[image: View Post]rhubarb, on 03 December 2009 - 06:40 PM, said:

[image: View Post]Talon, on 03 December 2009 - 03:42 PM, said:

how would you fix or check an air/vacum leak?

Check the condition of the carburetor boots and clamps. Loose clamps or cracked boots can cause an air leak.


the boots do not seem to have any cracks and the clamps are all tight.