Bleeding Air

OK, having troubles bleeding the air out of the system. Both pipes under the car are cool to the touch after running the engine to the operating temperature. I have a expansion tank in the engine compartment. The large tube in the expansion tank is T'ed in the the heater lines which are connected together. The radiator is in the front of the car and I have checked to make sure I have the lines in the correct orientation. The vent tube out of the top of the radiator is connected to the top of the expansion tank. The expansion tank is staying full but I have only placed 2 gallons of fluid into the system. After I run the engine do I need to raise the front of the car or the rear where the expansion tank is to help bleed the air? I am comfused. Any help would be appreciated.

What sort of car? What engine?

IF it is a Subaru in a Vanagon/T3, go to the SubaruVanagon group files and look at the wealth of information there. Most is written in US English too.

http://autos.groups.yahoo.com/group/subaruvanagon/files/

dave

flat_iv wrote:OK, having troubles bleeding the air out of the system. Both pipes under the car are cool to the touch after running the engine to the operating temperature. I have a expansion tank in the engine compartment. The large tube in the expansion tank is T'ed in the the heater lines which are connected together. The radiator is in the front of the car and I have checked to make sure I have the lines in the correct orientation. The vent tube out of the top of the radiator is connected to the top of the expansion tank. The expansion tank is staying full but I have only placed 2 gallons of fluid into the system. After I run the engine do I need to raise the front of the car or the rear where the expansion tank is to help bleed the air? I am comfused. Any help would be appreciated.

Sorry, Its a Suby 2.2 in a Ghia. Also, the expansion tank is higher than the radiator.

[ Edited on 29/8/2007 by flat_iv ]

I had a few dramas with this. there are two methods...

the slow;
running the engine up to temp and let it cool fully. top up coolent and repeat many times. can take a while, even a few days but it works eventually.

the faster;
fill the expansion tank up the top with coolent. leave the lid off. find the highest joint in the pipe work other than the expansion tank. back off the hose clamp and crack the join between the rubber and the metal so it can leak. if it doesn't leak straight away then you know there is air. if so, keep filling up the expansion tank till the joint starts leaking water, then tighten up the hose clamp again. put the lid on. viola! one bled up system. this cut my bleeding times down to 2 minutes from 2 DAYS!

here's my pipe work so you can see what I mean...



the pipe snaking up toward the top left is the pipe in question. the reason I have issues is because the expansion tank only runs into my top engine coolent pipe, while the bottom hose climbs up quite high to avoid the wheels on the side of the car.

hang on just a second...you have got a thermostat in the motor? if so, the top pipe will be warm but the bottom pipe will be cool until the car has been running for a while. If you haven't got a thermostat, repent of your evil and put one in straight away. 😉

[ Edited on 29-8-07 by pete wood ]

btw if the radiator has a cap, you can crack that to bleed the air out there. 😉

Thanks for the insight. I do have a thermostat. I will definately crack one of the lines open until the air passes and a little fluid runs out.

I believe that I have all the air bled out of the system. I am a little concerned about the temp's. Right now I am using a VW Golf radiator that has a thermo fan switch mounted to the bottom of the radiator. The fan switch is a 2 stage 85/93 (185/200). When my engine temps hit 190 1 fan turns on and stays on for approx. 5-8 min. I guess the reasoning is the engine water is hotter than the water in the radiator. I am getting my engine temps at the water manifold with an aftermarket gauge and sender. Is there any reason for me to be concerned in the difference in temps? Or should I let the ECU control the radiator fans?

[ Edited on 31/8/2007 by flat_iv ]

Hi

Used to use a Davies Craig adjustable fan swith mounted in the top hose and I would get the same long fan duration that your getting, when I allowed the ECU control the temps the fan only ran a short time as needed. This was partly because I was trying to keep the temps to low which made the fan stay on longer.

Steve

I have done some searching on using the ECU to control the fans. Am I correct the stock ECU produces a ground to turn the fans on?

[ Edited on 1/9/2007 by flat_iv ]

Hi

I'm not sure about stock ECUs but I used an after market one and it used ground to operate the fans, I used it to earth a fan relay.

Steve

flat_iv wrote:I have done some searching on using the ECU to control the fans. Am I correct the stock ECU produces a ground to turn the fans on?

[ Edited on 1/9/2007 by flat_iv ]

Yup, you're right - the ECU grounds the relay(s)
Edit: It also grounds stuff like: Immob light, ECL etc It's to stop the ECU supplying high currents

Mine's an EJ20 European spec (yours may vary, although my '02 Impreza manual shows this for the US market too).

There are two relays:
1/ For the A/C fan (if fitted)
2/ Main fan

The ECU switches in the A/C fan at a lower temp threshold.
The main fan is dependant on:
1/ Vehicle speed
2/ Engine temperature

ie it doesn't come on at the same temperature is speed is higher.
If you're not using a VSS it will come on at a lower temp

For a scan from the manual look here:
http://www.vwkd.co.uk/bb/viewtopic.php?t=361
(it's at the bottom of the page)

Of course that's running a standard Scooby wheel and using a Scooby VSS (4 pulse per wheel rev, 5V pulse)

HTH

[ Edited on 1-9-2007 by ElusiveStranger ]

I didnt realize the engine fans cut on between 203-210F. That is hotter than I had imagined. My diagram shows 2 wires from the ECU to control the fans. I am guessing 1 is for the main cooling fan and the other is for the air conditioning fan. Since I have 2 fans on my raidator I am going to have them both turn on by the main fan control. After I get this wired up all I like is the radiator shrouding, speed sensor and to relocate my fuel pump that is mounted on the front wall opposite of the master cylinder. When the fuel pump runs it sounds like to is vibrating the front wall to death. Might just add a few rubber washers to see how it reacts before I relocate it.