HELP, Surge tank severly leaking!

[Dr.304]

Hey all, i just picked up a VN Calais 1990 from this guy in my street...very good condition, 156000kms on the clock, S2 engine, Auto.
I just got a blue slip and i got 1 yr rego on it yesterday!
this arfternoon, i was showing the car to my mate (and btw i have been driving it all day!) and as we pulled into his driveway and turned the car off, we got out and noticed that a ****load of coolant was leaking! like a flowing river!
we popped the bonnet and we noticed it was pouring out of the surge tank with the lid tight on! the coolant was a nice light green colour.
I dont know what happened? the coolant comapartment still has a max level of coolant in it, so i started her up and slowly started to add come water into the surge tank and left her idling for a bit....i dont know what happnened???
And also the mechanic we took it too said everything was fine, even though i dont know if this is serious?!?!?!

Feedback would be greatly aprreciated!!!

thanks

[SthEastCustoms]

dont know the condition on ur tank but alot of them split and crack i know mine has but a replacement from holden is better than buying a second hand one that will do the same sooner, they charge 68 brand new and genuine you cant go wrong

[immortality]

possibly an old tired radiator cap. is the radiator still full?

[Dr.304]

still full?
there is a compartment where you put coolant, which is full then there is the surge/overflow tank which the problem was at.
its wierd it just happened out of no where.
im about to unscrew the surge tank lid and take it off and let the car run until operating temp see how that goes..but could it be thermostat?
the other thing is that the engine hasnt overheated....
HELP!

[Dr.304]

please i need help, came out of nowhere?!?!!?!?
wat to do?
any thoughts would help or could fix...
only seems to happen at operating temperature.......like this arvo i tried to come a conclusion about why it does this.
I unscrewed the surge tank cap and started the car without the lid on...let it idle for about 3 mins (before operating temp) then turned it off.
Nothing happend, as in the surge tank didnt overflow.
I turned the car back on again and let it reach operating temp(as in the radiator fan comes on automatically) then i turned the car off.
All of a sudden coolant started to rapidly fill the surge tank and eventually overflow (without the lid).
Im pretty confident it is thermostat.
still not sure??

[immortality]

sounds like the radiator cap is loosing it's pressure and venting into the overflow tank. it's a little know fact that the coolant in th engine actually gets hotter when you turn the engine off. this increase in temp aslo causes an increase in pressure. looks like the radiator cap is venting that extra pressure. if you don't know when the thermostat was last replaced it wouldn't hurt to change that also

[SweetWagon]

sounds like you have s2 motor, but still have s1.5 cooling system they dont have a radiator cap.

an overflow cap is installed over the surge tank pressure cap (drivers side).
A coolant reserve tank is installed to the passenger side strut tower and an overflow hose is installed between the reserve tank and the overflow cap.

As the coolant volume expands due to a rise in temperature, the pressure valve in the surge tank pressure cap opens and allows the excess coolant to flow into the reserve tank via the overflow hose. When the coolant temperature falls, the vacuum valve in the surge tank pressure cap opens, allowing the coolant to siphon back into the surge tank.

so basically replace your pressure cap inside the surge tank cap, sounds like its not opening and the excess coolant has nowhere to go.

heres a pic of what the s1.5 cooling system looks like:

[immortality]

that is the s1 cooling setup. either way i think you need to replace the pressure/radiator cap.

[J_D]

that is the s1 cooling setup. either way i think you need to replace the pressure/radiator cap.

No, that is S1.5. Ive got a S1 and it doesnt have an overflow tank.

[SweetWagon]

that is the s1 cooling setup. either way i think you need to replace the pressure/radiator cap.

yeah its actualy s1.5, a bit different. doesnt have a radiator cap like s2 and has a different surge tank cap with an inbuilt pressure valve and hose fitting for the reserve tank (passenger side)

[immortality]

yeah, sorry, didn't notice the other tank on the other side. he still needs to replace that pressure cap though

[Dr.304]

hey guys, what i did was tighten the cap up...tight.
i dont think it was tight enough when it overflowed!! i think the mechanic we took it the he had an apprentice and he didnt tighten it engouh because when i tightened it, i tightened it until u couldnt physically tighten it no more!
no more leaks...for the time being!
but the other prob is that my cat completly fell off!! haha while i was driving the welding got rusted.
sounds like an V8 but making everything rattle like the centre console!

thanks guys

[immortality]

hey guys, what i did was tighten the cap up...tight.
i dont think it was tight enough when it overflowed!! i think the mechanic we took it the he had an apprentice and he didnt tighten it engouh because when i tightened it, i tightened it until u couldnt physically tighten it no more!
no more leaks...for the time being!
but the other prob is that my cat completly fell off!! haha while i was driving the welding got rusted.
sounds like an V8 but making everything rattle like the centre console!

thanks guys

hope you got a good deal on this car??