# how do i bleed the cooling system?



## SmashThat (Nov 15, 2005)

ok, i see the bleeder screw on the manifold, but what exactly do i have to do to bleed it? the cooling system is filled already


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## zellx2004 (Sep 30, 2004)

What do you mean by bleeding? Do you have an air pocket? in the system or are you just changing the coolant?


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## rogoman (Dec 16, 2004)

SmashThat said:


> ok, i see the bleeder screw on the manifold, but what exactly do i have to do to bleed it? the cooling system is filled already


Your best bet may be to drain down the coolant and start all over again with the filling of the coolant. 
Here's how I do it:
1 - drain coolant
2 - open the bleeder screw
3 - optionally jacking up front of car helps to purge air pockets
4 - fill system until coolant starts coming out the bleeder hole
5 - close bleeder screw (not too tight; screw is easy to break off)
6 - continue filling until coolant is at the bottom of the filler neck
7 - do not put cap on the radiator
8 - start motor; as coolant starts to warm up, you may see a few air bubbles
9 - squeeze the hoses by hand to free up possible air pockets
10 - put cap on radiator


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## SmashThat (Nov 15, 2005)

ok, i'll have to try it that way. i got my car running after all the work i've done to it. but after a little while of running, it starts to overheat and there is no coolant in the upper radiator hose. i was told probably the thermostat isn't opening, but i just put a new one in so i don't know.


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## rogoman (Dec 16, 2004)

What brand of thermostat did you install? If it was one of those aftermarket units like a Stant, there's a good chance that it'll cause more overheating problems. Get an OEM unit from a Nissan dealer.


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## Jordy240 (Jul 18, 2005)

here's the trick...it works every time....bearing that there isnt another problem...after working on the cooling system you gota put the coolant in and run up the vehicule with the heater on full deforst with full blower power...then continue to run the vehicule until the thermostat opens and youll see the coolant level come down..leave the cap off of course...when you see it go down...keep filling with coolant until it bubbles up....then after the coolant is hot...continue to run the car, and rev the engine up to about 2000-3000rpm, so the water pump is pushing the coolant harder...the coolant will bubble out the top of the rad...and while it is doing this put the cap on and tighten down...this is the way to do it without having to mess with the bleeder screw...cus i broke mine off in the block..so i was SOL...and this method worked.....if the car still overheates...then as soon as the temperature starst to climb past its usual spot, pull over and use a huge heavy thick towel and unscrew the cap slightly to let the pressureized air escape then screw back on...then drive some more...this will work the air out of the system... This whole procedure takes about 20 minutes of just letting the coolant warm up and so on.This should work for you though...oh and check the reservoir...if there aint anything in the reservoir...it will suck air into the system...the whole expand and contratc theory....messed around with my car for 2 hours till i figured that one out! hahaha


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## SmashThat (Nov 15, 2005)

ok...i'll have to try that, but i don't think my thermostat is even opening. its not an oem by the way rogoman, but its brand new


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## SonsofWisdom (Mar 29, 2004)

another good thing to try it lifting the front end up...if you have a hill or steep driveway that'll work...have the back end lower than front...this maket the radiator the high point so the air will end there.

the reason for turning the heat on is to make sure the hot coolant is flowing through your heater core...this does one thing mechanically...it just opens the heater control valve to allow coolant to flow into heater core...nothing special really ....just an fyi 

having the front up higher and turning on the heater are good ways to bleed out any air for sure. Try to find a radiator fill funnel...it has an adaptor that connects to your radiator via a raditor cap like connector...then a funnel fits inside that... you can fill the funnel up...then rev the engine slightly once the thermostate's opened...this helps push any air out...once you've gotten all the air out...gently squeeze the top radiator hose...plug the funnel...use whats in the funnel to fill res. tank...place rad cap on. Just don't squeez the hose too much...when you remove the funnel it'll suck in air..not much really but still.
(also called a no spill funnel...only no spill if you do the little squeezing the hose trick  )

the thermostate will open only after the car is suffeciently warmed up...top radiator hose will be hot to the touch and if you rev slightly you should be able to see the coolant rushing into the funnel...the level will rise then fall once you let off the throttle

if you don't have/can't get/don't want one of those funnels you can follow all the same steps...it'll just be a little messier is all...

Good luck


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