NC24 too hot?

[Neosophist]

Still having issues with my temp.

With the old rad cap the temp needle stays roughly in the middle of the gauge unless i'm on a long fast run (i.e motorway driving) where it will get towards the red. The expansion bottle fills almost upto the top but obv goes back into the bike when its turned off. i've not been on a looong run since I brought the bike but i'm thinking it'll probably let enough coolant expand to overfill the bottle as it had overflowed when i got home after buying the bike (150 mile run)

Now if I have the new cap on when the bike is warm the temp tends to stay in the upper section of the temp gauge and very little water expands to the bottle.

I've contacted david silver who i brought the cap off and they said i could send it back and they'd test it for me.

Flushed the rad, bled it for air, 50/50 coolant mix.

I've watched quite a few NC24 vids on youtube and their temps seem stable aroudn mid-way point.

New cap faulty? Don't wanna send it back and look like a plonker.

Fan hardley eveer comes on, but i've left it idling and it came on after aaages so it does work!

[fastdruid]

I still think it's the thermostat.

Druid

[spooky]

Whats the rad like, is the bit where the cap fits on damaged.

[fastdruid]

Still having issues with my temp.

With the old rad cap the temp needle stays roughly in the middle of the gauge unless i'm on a long fast run (i.e motorway driving) where it will get towards the red.

It shouldn't do that, on a constant high speed run although the engine is making a lot of heat it's also losing it fast (or should be). My 750 sits just under halfway on the motorway, ISTR the NC35 does too.

The expansion bottle fills almost upto the top but obv goes back into the bike when its turned off. i've not been on a looong run since I brought the bike but i'm thinking it'll probably let enough coolant expand to overfill the bottle as it had overflowed when i got home after buying the bike (150 mile run)

It shouldn't do that, there should only be a slight level change. Sounds as if the cap is leaking/releasing at too low a pressure.

Now if I have the new cap on when the bike is warm the temp tends to stay in the upper section of the temp gauge and very little water expands to the bottle.

The overheating isn't right but the overflow to the bottle sounds better.

Personally I'd try it without a thermostat, dunno about the NC24 but on the RC24 it's a 10min job to whip it out. You can then test the thermostat[1] plus you can ride the bike without it and see if it makes a difference.

Druid

[1] suspend it in water with a thermometer on a cooker and heat it up, the valve should open at something like 60-80 degrees (I don't have the manual to hand to check).

[Neosophist]

Yeah it's only 10 mins to whip the thermostat out, i'll try that next. Thanks for the suggestions and advice about the rad-cap FastDruid!

I chucked the thermostat in a pan of boiling water when i flushed the rad / cooling system and it did open but it might be opening late so I think i'll have to get the digital thermo on it later.

Seems the new cap would be ok then and the old one isn't holding pressure.

[Neosophist]

Same with the thermostat out..

I think I may have found the problem though....




It also doesn't turn

[kenny629]

yeah that might be it mate

[fastdruid]

Same with the thermostat out..

I think I may have found the problem though....




It also doesn't turn

OTOH it could be the pump....

Druid

[Neosophist]

Thats not the half of it! The shaft has actually snapped, thankfully on the waterpump end, I guess when it finally siezed that was the weakest point. Just gotta fish the piece of shaft out the sump before i put the new pump in.

Funny thing is i've driven the bike 1100 miles trying to sort out this running hot problem with no waterpump! hopefully the gaskets are still ok...

Ordered me a new 2nd hand pump so hopefully all will be gravy soon enough.

Thanks for the help / advice people.

Seems my problem was faulty cap / knackered waterpump, probed the stat earlier on, it's opening at 82c and fully open shortly afterwards so no probs there!