vn overheating heelppp

[sleekVL]

hey guys

having problems with my vn.
car was all fine used to drive long distences all the time without a problem.
driving into town one night and it overheated.
so ive put a new thermostat in it , its full off coolent n not leaking anywhere ,ive flushed the radiator,checked water pump, theres no white bubbles coming from the radiater , yet within 5 minutes of driving it nearly boils , can anyone help? any other ideas why its heating up?
my radiater hoses are soft , a mate told me there sposed to be hard n that could be why, is this true?
use guys seem to no a fair bit n this site seems good for help so thort id throw it up.ive tried eveyrthing i can think of
its a s2 v6.
thanks heeps in advance

[db_notso]

when the cars HOT (15 mins drive ISH) the radiator hoses should FEEL harder than when first start and cold
if there not hard then the car isnt holding coolant pressure
if you have no leaks.... try replacing the radiator cap and bleeding the coolant UNTIL THE THERMOSTAT OPENS

[FXST01]

How old is the water pump?
Take the belt off and see if the water pump turns easily and doesn't wobble.
You may even have to take it off just to rule it out, although sounds to me as if the impeller isn't doing it's job.

[db_notso]

caps die all the time and are a cheap part and when too old would cause this fault
the pumps normally die at about more than 200,000km's have seen them last 300,000km's

[pow3rslave]

i'd also be looking at the welch plugs (search for welch or welsh on the forum) there's one at the front and the back of each head, and i think some on the side of the block beneath your exhaust manifold, also some at the back but you need to take the gearbox off to get to those. they're little brass plugs about the size of a 10c/20c coin. just check them to see if they're corroded or look like they could have leaked.

[sleekVL]

How old is the water pump?
Take the belt off and see if the water pump turns easily and doesn't wobble.
You may even have to take it off just to rule it out, although sounds to me as if the impeller isn't doing it's job.

ill give it a go tomoz man.thanks

[sleekVL]

caps die all the time and are a cheap part and when too old would cause this fault
the pumps normally die at about more than 200,000km's have seen them last 300,000km's

is there any way of telling if its the cap without goin out n buying one? thanks heeps for your help man.

[db_notso]

well if you got no leaks and coolant full and fan is all good and pump isnt noisy and turns freely and no oil contamination gearbox or engine (if has auto cooler...)
then i would put a cap on and see if it comes up too pressure
are you losing coolant? do you have to top it up all the time?
is there a puddle under it when you park when its hot? (puddle that isnt from ac drain tube e.g. is coolant not clear water)

[db_notso]

oh you can check if its rubber seal is cracked or brittle and hard
should be soft and flexible
if cap is rrooted then probably have a stain around the radiator near it

[sleekVL]

well if you got no leaks and coolant full and fan is all good and pump isnt noisy and turns freely and no oil contamination gearbox or engine (if has auto cooler...)
then i would put a cap on and see if it comes up too pressure
are you losing coolant? do you have to top it up all the time?
is there a puddle under it when you park when its hot? (puddle that isnt from ac drain tube e.g. is coolant not clear water)

nah not loosing any coolent, no puddles under car.the rubber on the cap has eroded a bit on one side , dosent seem like much though , and the spring is hard to push in and out? is it supoosed to be easy? i never thort something as simple as a radiator cap could make the car overheat the way it does , learn something new everyday i guess.

[FXST01]

is there any way of telling if its the cap without goin out n buying one? thanks heeps for your help man.

Might want to check the pressure rating of the cap as well, my VP book states 135 kPa opening pressure (i assume the VN will be the same).

[wraith]

Yeah the same. Pain in the butt part is the SCA catalogue list's the radiator cap as something like 90kpa. I can't remember the exact wording but it goes along the line the higher the kpa the higher the boiling point of the coolant.

[db_notso]

i believe its supposed to be like 130 isnt it? pretty sure its higher than 90
more pressure means higher temperature it can reach before vapourising inside system

any erosion or pitting or cracks on the seal is a failed radiator cap
if anywhere on the seal isnt complete this lowers the amount of preasure it can hold and there sssooooo cheap worth a try buddy
before you get to involved in what might be a simple problem

[sleekVL]

i believe its supposed to be like 130 isnt it? pretty sure its higher than 90
more pressure means higher temperature it can reach before vapourising inside system

any erosion or pitting or cracks on the seal is a failed radiator cap
if anywhere on the seal isnt complete this lowers the amount of preasure it can hold and there sssooooo cheap worth a try buddy
before you get to involved in what might be a simple problem

yeah 135 man.yeah gunna get a new cap n see what happens.will let yous no how it goes thanks for all the help.

[timbodavo]

Very important to bleed these correctly. You should be able to feel all your radiator and heater hoses hot once thermostat has opened and turn your heater on inside car. Are you getting hot air through vents. If not you have air locks or blockages. Also check your thermo fan kicks in at around halfway with the ac switched off. If it does not come on and it gets over halfway turn the ac on if your fan cuts in then you may have an issue with your fan switch.

[VK SL 3800]

Its unlikely but you could have and internal blockage and you might have to back flush the engine, a hit of compressed air wile flushing helps heaps.

+ 1 for water pump.

[sleekVL]

Very important to bleed these correctly. You should be able to feel all your radiator and heater hoses hot once thermostat has opened and turn your heater on inside car. Are you getting hot air through vents. If not you have air locks or blockages. Also check your thermo fan kicks in at around halfway with the ac switched off. If it does not come on and it gets over halfway turn the ac on if your fan cuts in then you may have an issue with your fan switch.

i dont think my heater has ever worked since i bought the car? does this matter? is it too late to do this now tht ive already flushed the radiator and whatnot?

[wortus]

is there any way of telling if its the cap without goin out n buying one? thanks heeps for your help man.

Yes what generally happens when the cap is faulty is that the coolant expands into the overflow and won't go back in so you will notice air in your radiator and the overflow will be too full.
Apart from that make sure it is bled properly and that the radiator is not blocked up. Other than that has the coolant been kept up to scratch? Could be a corroded impeller on the water pump?

[sleekVL]

hey guys , brand new radiator cap on todai n still overheating , weird tho its runs around 3 quaters hot when driving , but drops to just over half way wen stationary?

[db_notso]

shouldnt go to red or any higher than three qaurters on gauge...
if below these than is not overheating.....
if goes to top then its got issues.

if it is hot when moving and sits at half FOR LONG PERIOD OF TIME @ idle then i would suggest bleeding system of air and checking after this if it is loosing any coolant
before going any further