coolant issue, need quick answer please.

[Bludger]

radiator filled full, overflow correct level.

When it gets to operating temperature, coolant flows to overflow.
When it cools, coolant stays in overflow, doesn't go back to radiator.
Radiator level is down.

what is the problem?

changed cap already.

[Bludger]

changed both small hoses....... the one inside the overflow and also the one from the overflow to radiator.

I can see the problem, but don't know how it's occurring.

Overflow bottle and pipe are a little bit clear and i can see there is a break in the coolant flow. Can see the blue coolant going into the bottle but out of no where there is air.

It breaks the flow of coolant back to radiator.

Just 20 minutes running and its missing several hundred ml from the radiator.

Just doing my head in trying to figure out how and why......

[Bludger]

going on a long trip tonight, need it fixed.

Can't see leaking coolant anywhere.

[TODA AU]

What radiator is it? ( stock or aftermarket)
Is it def the correct cap?
Is the thermostat opening?

[markismaximus]

Is the overflow OEM and in the original location?

[Bludger]

Is the overflow OEM and in the original location?

yes.

What radiator is it? ( stock or aftermarket)
Is it def the correct cap?
Is the thermostat opening?

Koyo dc2 radiator, tried 2 caps, correct caps, definitely.

thermostat opens. bottom hose can be felt cool then later hot.

[Bludger]

one cap is cpc one from supercheap, other is denso one that came with radiator.

should i buy another cap again?

[markismaximus]

with the koyo rad does the cap sit at the same height as the original rad? not sure if a difference in height could cause issues

Is the small hose in the overflow cut at an angle so the pipe isnt being blocked?

Possibly try lifting/lowering the overflow bottle to see if a change in height makes any difference

[Bludger]

with the koyo rad does the cap sit at the same height as the original rad? not sure if a difference in height could cause issues

Is the small hose in the overflow cut at an angle so the pipe isnt being blocked?

Possibly try lifting/lowering the overflow bottle to see if a change in height makes any difference

I'll cut it now, doubt it would make difference.

small hose diameter was 8 or 9 mm. new hoses are about 5 or 6 mm.......

make a difference?

height shouldn't be an issue, was working well for a while. but really can't tell because it has always had some leaking issue unrelated to this. so the coolant level was never stable.

Now I've fixed everything i can think of and this happens.


inside where the cap goes, it has turned black, the silver alloy has turned black where the cap seals.

will this cause sealling issue?

i wanna buy another cap but if i'm wrong, i waste more money.

[nickk]

Are you 100% sure there are no leaks?

Is the amount of coolant going into the overflow approximately the same as the amount your losing from the rad?

Drain your coolant into a container and flush the system for 5-10 mins with a hose, see if any crap comes out.

How old's the thermostat? Just because the bottom hose gets hot doesn't mean the thermostat is fine, could be opening only slightly.

[markismaximus]

I'll cut it now, doubt it would make difference.

small hose diameter was 8 or 9 mm. new hoses are about 5 or 6 mm.......

make a difference?

possibly. decreasing the size of the hoses will make it more difficult for coolant to pass through them. As more vacuum/pressure is needed to move the same amount of coolant.

Has this only started happening since changing hose size?

height shouldn't be an issue, was working well for a while. but really can't tell because it has always had some leaking issue unrelated to this. so the coolant level was never stable.

Now I've fixed everything i can think of and this happens.

I see, so it was working previously with the same setup

inside where the cap goes, it has turned black, the silver alloy has turned black where the cap seals.

will this cause sealling issue?

i wanna buy another cap but if i'm wrong, i waste more money.

as long as there is no gunk or buildup around the seal the blackening of the alloy shouldn't cause any sealing issues.

thats just the way diagnostic repairs go unfortunately. you'll spend money on new parts purely to rule them out as the cause

[Bludger]

F it, I'm just gonna buy a new cap and leave it at that till i get back.

Coolant capacity is about 9 liters and I'll carry a spare bottle of coolant with me.

Highway driving, the fans never get to turn on anyway with the Koyo being so efficient.

I'll check back with results...........

Such a pitty cos since the rebuild, the c2 has been nothing but a charm to drive, lovely power, smooth delivery.
Just small little BS issues, been dealling with them ever since the rebuild.