Best way to bleed air from VR cooling system

[Bizmark]

Ok i i changed my coolant in my V6 VR a few months ago as a mechanic recommended it, since then i've been having airlock problems in my coolant, the water will get halfway to H and engage the thermo even when cruising along the freeway. Before dropping the coolant the car was almost always on 2nd mark from cold (1/4 way to H) and never went much over that.

I tried to fix the problem by cracking open the bleed screw on the thermo housing after a drive and letting some air/coolant out until it appeared nothing was coming out. Did that many times and no improvement in my cooling problems.

Did a full cooling system flush late last week and i'm still having the same problems. There seems to be a heap of air in the system this time as well. I've tried to bleed the car while cold by jamming a coolant bottle into the radiator cap and cracking the bleed screw open. It seemed to push out a lot of air but it definitely hasnt got it all.

Whats the best way to finally get rid of ALL the air in my coolant? Been having this problem for months and its really starting to annoy me.

[tezza]

The way I did my VS was the following (from the Gregory's manual):

1. set the heater control to hot
2. disconnect radiator hose at the thermostat and hold vertically
3. pour coolant into the hose until it flows from the thermostat cover and quickly replace the hose onto the thermostat cover
4. undo the bleed screw and start the car and let it get up to operating temp and put the bleed screw back on when water is flowing from the bleed screw constantly

[shadetreemechanic]

The way I do it is very simple. Get an empty bottle of gatorade/Just Juice and cut the bottom. Open the radiator cap and stick it upside down in the radiator spout (hold it down firmly for a good seal). Open the bleeder nipple and fill the bottle up with coolant till it comes out the bleeder. Close the bleeder and replace radiator cap.
If you judge it right you'll only spill a tiny bit of coolant from the bottle when removing.

[Bizmark]

The way I did my VS was the following (from the Gregory's manual):

1. set the heater control to hot
2. disconnect radiator hose at the thermostat and hold vertically
3. pour coolant into the hose until it flows from the thermostat cover and quickly replace the hose onto the thermostat cover
4. undo the bleed screw and start the car and let it get up to operating temp and put the bleed screw back on when water is flowing from the bleed screw constantly

Gave that a go, but on step 3, i never saw any coolant flow from the thermostat cover. Just ended up filling the hose, that led into the radiator. The VR has a different engine to the VS though.

The way I do it is very simple. Get an empty bottle of gatorade/Just Juice and cut the bottom. Open the radiator cap and stick it upside down in the radiator spout (hold it down firmly for a good seal). Open the bleeder nipple and fill the bottle up with coolant till it comes out the bleeder. Close the bleeder and replace radiator cap.
If you judge it right you'll only spill a tiny bit of coolant from the bottle when removing.

Tried that but with a 5L distilled water bottle with some tape around the bottle neck. I found that i had to open the bleeder a fair bit, and the coolant was only dribbling out. Still had air in the system after that. Most likely its in the block rather than the radiator.


I'm still stuck with air in my cooling system... Any more ideas?

[Brett_jjj]

Is it overheating at all?Ive serviced a lot of VN-VS radiators,and Ive never had trouble with trapped air in the cooling system.I always make sure the car is facing uphill before refilling the cooling system though.I used to muck around with the bleeder screw after refilling until I read in the workshop manual that its not necessary to use the bleeder screw,unless your using a special holden bleeder tool,so I stopped using it,and Ive still not once had a problem.Id try facing the car uphill and filling the cooling system.The bleeder tool applies a vacuum to the cooling system whilst it is being filled with coolant.Some people say that a cut off bottle replaces this tool,but I cant see how a cut off bottle will apply a vacuum to the cooling system while its being filled with coolant.You could see someone who has one of these filler/ bleeder tools.That should prevent any trapped air.

[Bizmark]

It runs hotter than it should. It will get hot enough to bring on the thermo (about 1/2 way up on the temp gauge) even if cruising along the freeway for about 15-20 min. As far as i know, these cars should never get hot enough to bring the thermo on if moving more than 40kmh. The coolant was flushed and refilled on flat ground.

[Brett_jjj]

Try topping it up with the front of the car higher.Id get the cooling system pressure tested to confirm any internal leakage problems first up..Though it could just be a blocked radiator, Ive also heard a few times of the water pump fins being worn away on some of the cheaper water pumps,this could also be the problem.Id start with the pressure test,and maybe get the radiator cleaned.Then if its still no different,replace the water pump.

[Bizmark]

Radiator seemed fine when it was being flushed. Both radiator hoses build up pressure when the car is at operating temp. Water pump would have been replaced no more than 1 year ago so i doubt it'd be corroded.

I'll look into a pressure test if i don't get the problem solved soon.

Something worth noting, when bleeding from the bleed valve, when a bunch of air bubbles/froth comes out, the temp reading on the dash does come down a bit.

[Brett_jjj]

Id definitely try topping it up with the front end higher up so all the trapped air comes forward to the front of the engine and to the radiator..See how that goes.Also make sure the heater tap is opening up properly.If its not opening properly,it will trap lots of air.Just watch the heater valve whilst someone turns the heater settings to hot with the engine running.You should be able to see the valve move as it opens.The engine has to be running for the vacuum supply to open the heater tap which is vacuum operated.

[Bizmark]

Is it simply a case of jacking the front up, top off the radiator, then lower the car again. Or do i need to have the front elevated for some time?

[Brett_jjj]

Just have the front higher by parking on a steep slope, or even jacked up or on ramps whilst its being topped up.Then put on the radiator cap.I have a steep slope at the end of the driveway I park on to refill the radiator.All I do then is check the overflow bottle/coolant reserve bottle level for the next couple of days,just to keep an eye on it to make sure everythings ok.If this makes no difference,then definitely check that the heater tap is opening.

[shadetreemechanic]

Hmm, from what you're saying it doesn't sound like trapped air (or definitely not enough to cause your symptoms)
I'd be yanking out that thermostat and checking it out..sounds like its bung.
If the water pump is ok, the radiator is fine and air is bled out sufficiently, you shouldn't see temp climb when cruising on the highway.

[Bizmark]

Thermostat seems to be working. It's an 82c one. From dead cold, the car will heat up to the 2nd line up from C (1/4 way up), then the thermo opens up and temp falls down to the 1st line, after that it steadily rises up to about halfway, sometimes the thermo fan manages to cool it down to the 3rd line, other times it stays at 1/2 way up the temp gauge or goes slightly higher.

[shadetreemechanic]

This is similar to what I posted about a while ago

Engine seems to overheat if aircon isn't on all the time

Run it with the aircon/thermo on all the time and see how it goes. If still no good, then I'd say the pump isn't doing its job or there is some sort of blockage restricting water flow. Or even the radiator cap, maybe it's not holding the pressure well enough (rated to 135Kpa)

[Bizmark]

Aircon on all the time didn't help, if anything it may have made it a little hotter. What did help slightly was heater on full and blower fan on full.

Radiator cap hasnt been changed in the last 2 flushes. What would be the signs of a failing radiator cap?

[The1]

radiator cap just keeps the top sealed and keeps the pressure right / controls overflow to the bottle and back into the system.

If your running a 81c thermostat it's best to get your fan cut in / out temps changed to suit the thermo.

[moose man]

I'd be testing your thermostat first. Take it out and boil it, and see what temp it starts to open (if it's not already stuck open).
It sounds like your temp guage is moving too much. A normally operating system will cause very little needle movement at high speed, this is the job of the thermostat.
Oh, and in my opinion 81 deg is too low, but that's just me. Whatever you do though, leave it in the engine.

[shadetreemechanic]

Yeah it's pretty clear now the problem is between the radiator and engine (the heater is plumbed straight into the block and is cooling the water when you turn it on)
Like mentioned before the problem MUST be the thermostat or some blockage in the radiator.

[Bizmark]

Oddly enough, went for another drive this afternoon, with heater control on full cold, still running a bit warm. Turned it to full hot, and temp went up a bit this time.

Btw, ive had some gurgling noises from the heater core area when i set the temp control to H. So there's airlock in my heater core, does the gurgling mean the air is going from the heater core into the block and thus casing my temp problems?