How do you Bleed air out of a coolant system?

[ap116862004]

How do you Bleed air out of a coolant system on a 4cyl ?
Do i need any special tools?

[Fredsvt]

No special tools.

Before filling, look on top of the housing the thermostat goes into. There's a 12mm bleed bolt there.

Open it, and fill with Type 2 until coolant flows out. Close bleeder, finish filling, add a little bit extra in the reserve tank and you're fine.

Do not open the bleeder with the engine running, or fill the system with it closed.

[Chadley]

Is it the same for a V6? (J30A1)

[Fredsvt]

The V6 bleeds through the rad cap as you fill as it's the highest point. You just have to fill it at a slow controlled rate to allow it to fill properly.

On either car, make sure the heat is turned up all the way (key ON to make sure the valve opens, then shut it off) before draining or filling.

[Chadley]

Even though I remove my thermostat, I turn up the blower motor and temp. all the way.
I always fill the radiator and overflow bottle full, then start the car. Then I just add coolant to the overflow bottle when it gets low (about 3 times) without losing the syphon.
What is this 'slow rate' you speak of?

[Fredsvt]

You don't want to pour the coolant in too fast into the radiator, the air won't escape, or it'll back up and burp out with coolant. To put about 1.5 gallons in, it should take about 5 to 10 minutes at the filling speed to let the air out.

Why did you remove the thermostat? What is now sealing the housing to the water passage?

[Chadley]

I take the thermo (and gasket) out so I don't have to wait for the water to heat up. It doesn't leak too much. Next time, I'll leave the gasket in and see if that works.

[Fredsvt]

I still don't get why you'd do that.

The stat (OEM) has the jiggle pin that lets air get past.

It's completely not necessary to leave it out, and draining out coolant of a hot aluminum engine is a VERY bad idea.

[Chadley]

FredSVT; you are VERY knowledgeable, however, I think both of us are missing something(s).

1. I drain everything from the pet**** <sp?>

2. I remove the thrermo and gasket, toss out, and reconnect.

3. I fill radiator, now very slowly, and overflow bottle full with H20.

4. I start car, put heat and blower motor on full blast, and fill cooling system to capacity (1.5-1.6 gal.) and let it run for like 5 min.

5. Shut car off, water is not too hot and drain. Repeat 3X. (By third time water is usually HOT and I wait a bit, as not to scold myself and concerned about alum. engine.)

6. Drink a beer or two. (approx. 30 min.)

7. Repeat steps 3 and 4 with Honda Type II.

7. I replace thermo and gasket w/ new thermo and gasket.

8. Repeat step 5 ONLY twice.

9. Finish remaining 4 beers. Entire process takes a couple hours, perfect for a Saturday afternoon.

[Fredsvt]

Ah, ok.

That's a bit overkill, but if you have the time and refreshments to go along with it, more power to you!

I usually just drain the rad, drain the rear half of the block at the valve just above the right axle, and pull the front block drain bolt. Then refill.

[Chadley]

I tried that, is there a block drain bolt on the left side axle??

Do you know where the front block drain bolt is? My haynes manual shows neither.

[Fredsvt]

If you look above the right side axle on the block, you'll see a little spigot, that's the rear block drain. It has a small bolt (12mm) that opens and closes it. It's very close to the support bearing, iirc. You can put a small hose on the spigot and run it into a bucket.

The forward drain bolt, look just to the driver's side of the forward exhaust manifold. You'll see a large bolt with a 19mm head, that's the one you remove to drain the forward bank of the block. It does make a huge mess.

[Chadley]

Thanks for all the info FredSVT, I'll tell you how it goes this weekend!!

[Chadley]

FredSVT, everything went well, that 19 mil bilt in frint was HUGE!! and made quite a mess

[Fredsvt]

Yes, it does. Kind of hard to catch all that coolant that rushes out.

The accessory block heater goes there, should it be needed.