proper coolant bleeding procedure?
 

Right now i'm trying to bleed my cooling system. The procedure I'm using goes as follows:

1. Place car on ramps
2. start car with heater open
3. unscrew bleed valve
4. open coolant tank cap
5. pour in coolant and water until it runs steadily out the bleed valve
6. close cap and valve and drive until thermostat opens
7. repeat 3-5

Once the thermostat is open and I try to open the cap the whole thing just sprays coolant everywhere because the system is pressurized and it completely defeats the purpose of bleeding it. Where am I going wrong? Do I need to drain it completely before starting?

No, you've pretty well got it.

What I do is, with the front of the car raised, after a steady stream of coolant comes out the vent, I cap it off and let the car run, idling till the fan cycles on.

Then I turn the car off, let it sit till it's cool, then check the bleeder again - adding more coolant to make sure only coolant - no air - comes out. Then it's good to go.

I usually end up with the resevoir too full - but the excess drains off through the overflow.

Here's the page at Clark's - http://www.clarks-garage.com/shop-manual/cool-02.htm

Is your car overheating, even after venting?

Delete step 6 & 7. Just keep the car idling, dont go and drive it.

And it's going to spray all over the place. This isn't a clean job. Once it's done shooting air out, let it keep pouring some coolant out for another minute. then put the bleeder screw back in and close things up.

Here is a neat trick for bleeding...

Place a one foot piece of heater hose in the opening of the overflow bottle. Wrap duct tape around the end if necessary to make a tight seal. Place a funnel in the other end and pour coolant in with the bleeder open. With the higher elevation of the funnel, coolant will be pushed out through the bleeder faster. You also won't need the ramps to raise the front end either!!!

Alternatively, you do not have to run the car and therefore deal with hot / moving parts.

With the car on ramps and the heater valve fully open, you can use a pressure tester to pressurize the system to 10 PSI and them open the bleeder screw to bleed the air out. Once you have a stream of coolant coming out, close the bleeder. Remove the pressure tester from the coolant reservoir and refill for the coolant that is lost. Repeat several times to ensure that you have bled the air out. A test drive will reveal if this is the case. If not just keep repeating.

Only problem with that method is that it doesn't get past the thermostat, which since it's cold, wont be open.

drill a small hole in thermostat before inserting into pump housing. if you haven't done this, don't worry, you'll be okay.

skip to adding coolant....

place a terry cloth towel around the bleeder screw body.

add coolant with the bleeder screw open until you can just see the hole in the bolt.

fill until coolant is coming out of the bleeder.

keep the filler cap OFF!

run car with the heat on full blast, idling.

add coolant as the reservoir level drops.

when the blower is giving you completely hot air, there is coolant bubbling from the bleeder, and there is still coolant in the reservoir, THEN you tighten the bleeder screw.

AFTER tightening the bleeder screw, replace the filler cap.

turn off the engine.

you may have to repeat this one time after the engine cools, but i doubt it.

To make sure that my 85.5 cooling system is thoroughly bled - I simply keep the correct socket on board as I drive it around (after doing the stationary bleeding first), and whenever I stop, I pop the hood and open the bleeder bolt (slightly so as not to make a mess) until I get liquid. My theory as to why this works is that driving the car helps extra air move to the top of the system, where it is easily bled out.

^^ i like this idea as well. just be sure to unscrew the bleeder VERY slowly!

Yes very carefully.... Speaking from experience:) I like to put a rag underneath the bleed screw and one draped over the top of the area to catch any spray.

hpservertech, you are right. I generally, will do another bleed after having run the car in stop and go traffic, just to be sure.

Hi! Did the bleeding by following Clarkes-Garage and my modified and scrapped coolant cap plus compressed air. Worked well!
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Lapponia 1984/944 n/ahttp://forums.pelicanparts.com/uploa...1213378358.jpg

Good thing you didn't blow your line or your radiator or your heater core even maybe your head gasket with putting 150 psi of air into the coolant system. Please use a valve to control your air pressure10 - 20 psi is good enough to bleed the system . Think about safety and your wallet LOL
Have fun not damage something alse on the way

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Bud

Oh, I knew I had to use a low... very low pressure of course. In the worst case cap would open up like when engine is boiling but that has never happend to me LOL.
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Lapponia

I pressurize my coolant tank with my mityvac (mine has two ports - pressure and vacuum - not all of them do...). I couple it right into the reservoir overflow tube open bleeder and pump just a little and wait until all liquid. Works well for me, but I usually also bleed off a little "steam" after the first trip or two to be sure.