NC30: Coolant overheating?

[Neosophist]

Ive not filled the coolant from the back always the front, i dont think the temp gauge has not gone ( or not far ) past the 90 mark, never enough for the fan to come on anyway.

I can see theres a lower and upper level on the rear reservoir, but when the bikes cold where should both the rads and rear reservoir be filled to?

I did get a new cap with the rads, my dad said the original one would do a better job, ill dig around for the one that came with the new rads and try it out aswell.

Extra info: the coolant hasnt yet leaked from the rad cap, only the bleeder in the rear reservoir

The level should be filled to the MAX mark when cold.

The rads should be filled to the very top.

The coolant goes into the resevoir bottle by going past the cap (it lifts up slightly when the pressure is too much)

[RonniB]

Ive not filled the coolant from the back always the front, i dont think the temp gauge has not gone ( or not far ) past the 90 mark, never enough for the fan to come on anyway.

I can see theres a lower and upper level on the rear reservoir, but when the bikes cold where should both the rads and rear reservoir be filled to?

I did get a new cap with the rads, my dad said the original one would do a better job, ill dig around for the one that came with the new rads and try it out aswell.

Extra info: the coolant hasnt yet leaked from the rad cap, only the bleeder in the rear reservoir

The level should be filled to the MAX mark when cold.

The rads should be filled to the very top.

The coolant goes into the resevoir bottle by going past the cap (it lifts up slightly when the pressure is too much)

No, the chinese rads are bigger capacity than oem honda.

The resovoir is made for a coolant expansion of approx 5-10%, lets say 10, of the 2 liters of coolant. So when hot 200ml of coolant is pushed to the resovoir, which is sucked back as it cools down.

Then you fit a bigger capacity rad, with the same pressure rated cap and the same type of coolant (same expansionrate). Lets say the new rads are 25% bigger, then the coolant system now holds 2.5 liter. This still expands 10%, which is 250ml instead of 200ml. So if the resovoir is filled to the max marking when cold, it might overflow when warm.

Ronni

[iArGod]

Before I go for a ride next ill fill the rear reservoir near the max and fill the front up see how it goes, thanks for all the feedback guys been very helpful yet again

[Mavirick]

No, the chinese rads are bigger capacity than oem honda.

The resovoir is made for a coolant expansion of approx 5-10%, lets say 10, of the 2 liters of coolant. So when hot 200ml of coolant is pushed to the resovoir, which is sucked back as it cools down.

Then you fit a bigger capacity rad, with the same pressure rated cap and the same type of coolant (same expansionrate). Lets say the new rads are 25% bigger, then the coolant system now holds 2.5 liter. This still expands 10%, which is 250ml instead of 200ml. So if the resovoir is filled to the max marking when cold, it might overflow when warm.

Ronni

I must say I agree RonniB if the capacity of the rads are bigger the expansion of the liquid will be more hence the reservoir isn`t big enough to hold the expanded capacity of the coolant. IMO

[CMSMJ1]

Before I go for a ride next ill fill the rear reservoir near the max and fill the front up see how it goes, thanks for all the feedback guys been very helpful yet again

Don't fill the res up to max - it will only piss out again.

Fill the rads up and put a wee bit in the res.

[Neosophist]

Interesting with over-size radiators.

If you know how bigger they are then you can work roughly how full the rear resevoir should be.

It's supposed to be filled to MAX with the stock rads so work from that.

My stock rads never seem to push water into the rear-resevoir, even with the fan on, well not an amount that is noticeable anyway.

If it's sending enough in there to make it overflowing I'd suspect cap / airlock first.

[iArGod]

Tried draining rear reservoir to just above minimum line, was fine for first few rides but still drained my coolant eventually, my dad reckons the spring cap in the top radiator isnt allowing cool water back to the radiators from the rear reservoir, possibility?

[CMSMJ1]

Tried draining rear reservoir to just above minimum line, was fine for first few rides but still drained my coolant eventually, my dad reckons the spring cap in the top radiator isnt allowing cool water back to the radiators from the rear reservoir, possibility?

Not in the way he thinks* - if the rad cap is not sufficently strong to keep the pressure in the system then it allows the fluid to boil earlier and start to run into the over flow.

It should all end up in a nice balance with a teeny bit of fluid lost when you really get it overflowing.

So..if the reservoir is empty when you set off and the rads are full to the brim - when you have finished your ride how much have you in the rads?

Getting a new rad cap is a good idea



*a poor cap will stop the cooler water coming back in but the bigger problem is that it is allowing the fluid to boil sooner letting more of it out!

[iArGod]

Tried draining rear reservoir to just above minimum line, was fine for first few rides but still drained my coolant eventually, my dad reckons the spring cap in the top radiator isnt allowing cool water back to the radiators from the rear reservoir, possibility?

Not in the way he thinks* - if the rad cap is not sufficently strong to keep the pressure in the system then it allows the fluid to boil earlier and start to run into the over flow.

It should all end up in a nice balance with a teeny bit of fluid lost when you really get it overflowing.

So..if the reservoir is empty when you set off and the rads are full to the brim - when you have finished your ride how much have you in the rads?

Getting a new rad cap is a good idea



*a poor cap will stop the cooler water coming back in but the bigger problem is that it is allowing the fluid to boil sooner letting more of it out!

Was that a question or are you asking me to try it?
You suggest getting a new cap but as far as i can see this cap is fine, it has a nice hold on the rad and the spring is fairly rigid; what other qualities make a good cap?

[CMSMJ1]

That the spring in the cap is of the specified weight.

you might have a 1.1bar cap.

you might have a 0.9bar cap - it would work fine, hold the head and the spring feel rigid

You might want to try a 1.2 or 1.3bar cap and see if it helps....