NC30 overheating problem

[davidjmclean]

Hi all,

I'm running an NC30 track bike, and it's got a (lovely) Rick Oliver sourced race radiator on it, but I'm having massive overheating problems. At a recent day at Rockingham it was so bad the coolant was boiling in the reservoir and it dumped loads out via the breather/overflow hose.

I'm wondering if there might be a fault with either the thermostat or the water pump, but to be honest I'm clutching at straws. Has anyone got any advice as to why this might be happening & what I can do to fix it? It's driving me crazy!!

Thanks & ride hard!
Dave.

[Cammo]

Best to start with the basics:

- Make sure the old radiator is clean and not blocked (run a garden hose through the top radiator and see what comes out the bottom radiator/engine).
- Take off the water pump cover and see what sort of condition the pump is in and that it’s working.
- It can help to straighten any bent fins on your old rad also, but I doubt this is solely responsible for your overheating.
- Remove the thermostat altogether, you don’t need it on a racebike.

If the system is in good condition it shouldn’t overheat.

[fastdruid]

Check your cap isn't knackered either.

Druid

[Morespeedvicar]

Try taking out the thermostat and giving it a run, but dont thrash it too much as it'll take a while to warm up.
Cheers
Ian

[Neosophist]

Check your cap isn't knackered either.

Druid

+1 on the cap! If you've got a good rad (and have bled it for air) check the rad cap's holding pressure!

My knackered rad cap was just letting water out the system whenever it got warm.

[davidjmclean]

Check your cap isn't knackered either.

Druid

+1 on the cap! If you've got a good rad (and have bled it for air) check the rad cap's holding pressure!

My knackered rad cap was just letting water out the system whenever it got warm.

I know this sounds daft , but other than checking that coolant isn't boiling out everywhere from the cap (which it isn't), what do I check for with it? Is there a pressure test I can do?

I've blown through the rads and all seemed fine, checked the thermostat & it's working within the recommended temps & values, checked the water pump which isn't seized, broken or anything, and I'm running out of ideas!!

[Neosophist]

If everythings working ok and your cap is holding pressure (ie coolants not pissing out everwhere from it) then it's one of two things.

either you have a faulty temperature sensor / temp gauge or both (you need a thermomeeter and a multimeter to check this one, the resistanance values @ specific water temps are in the haynes manual)

Or the more likely culprit is that you have air in your system! Have you bled it properly since filling the bike up with coolant.

You need to run the bike with the rad cap OFF until its warmed up and the stat has opened, then snap the throttle upto 5000rpm several times until no more air bubbles come out, gently squeezing the bottom hoses will help to purge and trapped air. Kill the engine, let it cool down and top the system up with more coolant and put the cap on. any further topping up is done from the expansion bottle (which should be topped up too ^_^)

There is a pressure testing tool you can get for a cap that will tell you what pressure it's holding, but if it's not letting coolant escape it should be fine.

If you've checked water pump, thermostat it's likely to be air ^_^... a new temp sensor is £30 btw

[davidjmclean]

Thanks, that's spot on advice. I definitely didn't go throught the process for bleeding you've described, so this sounds like a good place to start.