Why can I never bleed the radiator correctly?

After owing X1/9s for 10 years you would think the easy jobs would get easier.

Drove my son's X1/9 on the New Year's day drive with DCFiats and found a puddle of antifreeze under the front of the car. Put the up on a lift and found a loose hose clamp on the top passenger side radiator hose. Tighten the hose and checked all the rest.

Parked the car on a hill with the front of the car elevated. Took off the expansion tank cap, moved heater lever to open and started the car to warm up. Opened the radiator bleed screw and waited for the thermostat to open.

When the thermostat finally opened all the antifreeze spit out the fill hole on the expansion tank. No fluid came out the bleeder screw until I refilled the expansion tank with 2 gallons of antifreeze mix and put the cap on.

What am I doing wrong?

The radiator will only bleed...

under pressure. What you describe is setting it up at the highest point in the system (good) but then not providing the pressure to overcome gravity.

Leave the cap on the expansion tank so the system can build pressure, warm it up fully, then crack the radiator bleed. The pressure in the system will force the air out and the coolant up. When coolant starts to squirt out, you are done.

Pete

toddr124 said:

Parked the car on a hill with the front of the car elevated.

What am I doing wrong?

Click to expand...

I'm going to repeat what Pete said... the "tank" needs to be the highest point on the car to properly bleed the system.

What I do is this:

1. Jack up the rear - getting the tank even higher
2. Open heater valve
3. Fill system at expansion tank
4. open bleeder valve at radiator
5. keep filling system allowing coolant to escape out the bleeder (if it's really empty or full of air, you'll hear a lot of air escaping
6. Close bleeder
7. start car, let run until hot with cap off - probably a step I don't need to do.
8. Drop the car back down and enjoy..


This method has worked for me time and time again - no air.

Hope that helps!

toddr124 said:

Parked the car on a hill with the front of the car elevated
.....
What am I doing wrong?

Click to expand...

Park the car on level ground so that the expansion tank is higher than the radiator bleeder valve, and then keep the expansion tank full during the bleed.

The "nose-uphill" thing is only for bleeding the system under pressure - if you do it with the overflow cap off air is sucked into the system through the bleeder.

The system also needs to be bled at the thermostat housing. Some cars have a bleed port on the housing. If yours doesn't then loosen the hose clamp on the hose at the housing and jam a screwdriver between the hose and the housing so that air can escape. You should be able to fill until coolant comes out of the radiator bleeder, close the bleeder, keep filling until coolant comes out of the thermostat housing, put the bleeder cap back in and keep filling till the reservoir is full. Even with the car on flat ground that should be all that is needed.

This is why I am confused

All 3 approaches seem reasonable and better than what I did last night, but I am still not sure which is right. Maybe I can do all 3.

One comment on the last idea. The suggestion was to completely fill the expansion tank. I always thought we were to fill the tank only 2/3 of the way to the top to leave room for expansion.

Always leave "head space"

toddr124 said:

All 3 approaches seem reasonable and better than what I did last night, but I am still not sure which is right. Maybe I can do all 3.

One comment on the last idea. The suggestion was to completely fill the expansion tank. I always thought we were to fill the tank only 2/3 of the way to the top to leave room for expansion.

Click to expand...

If you fill it all the way up, and there is no air in the system, you are going to lose a bunch of coolant the first time the system heats up. That is, if your pressure cap is working as it should. If it's not and it doesn't release, then something else will pop (a hose, a connection, the expansion tank itself, etc)

I think what Matthew meant when he said "til the reservoir is full" is, "til the reservoir is full to the proper level". Same for what Eric said.

Pete

Pete Whitstone said:

I think what Matthew meant when he said "til the reservoir is full" is, "til the reservoir is full to the proper level". Same for what Eric said.

Pete

Click to expand...

Yes, exactly.

Pete Whitstone said:

Same for what Eric said.

Click to expand...

Yep... although given the choice I'd rather overfill a bit and let the pressure cap release the excess, than underfill. (If the pressure cap isn't working, then that's something else to fix).

I've always used the method described by Myron.

It's simple hydrostatics as long as the expansion tank is higher than the top of the radiator. Open the bleeder screw on top of the radiator, jack the rear up, and fill until antifreeze comes out the bleeder screw. If fluid escapes from the bleeder in this configuration there is little to no air in the top of the radiator. I suppose one could redo this after a hot run to release any trapped air that makes it way to the radiator. But I never have bothered.

Option #4 of possibly 99 others would be...

Use a Flush Tee high in the heater hose near the cam belt cover and hose pressure.

Works for me and has been for the past 30 years. (Remember though, I am blessed!)

More detail if you need it...