Coolant change - best way to get trapped air out??

fast401 wrote: Jack the front up so the radiator cap is higher than the thermostat and leave the cap loose. Done this many times.

I believe the cap is higher then the thermo without jacking?

401MATCOUPE wrote: I have many problems over the years with air in the system.  A bunch of years ago I bought a "Airflift".     http://www.matcotools.com/catalog/product/AC550000/AIRLIFT-COOLING-SYSTEM-AIR-PURGE/ I know it is a bit expensive for one time use, but I use it all the time in the fleet maintenance I do.  It pulls vacuum to leak check the system, if it hold vacuum, it will not leak.  The you use the vacuum to pull the new coolant into the system and eliminate the air pockets.  This is a great tool!!

X2
Several companies carry these vacuum assist coolant fill tools. They work great on hard to fill systems. Cheaper than a cracked head.

It also helps to repeatedly squeeze the upper radiator hose when you're close to having the rad completely filled. This will help burp out the trapped air as well.

                                .........Following is AMC V8 specific...........
         
 My cooling system Is now de-airlocked and filled..........Thanks go to all posters

No easy way.....'specially if working in garage / shop (spills=bad)....and also  thermostat installed
     
                  To me, most important part was to have coolant in heads, for sure.
        Running with air in heads is begging trouble......maybe blown head gasket (?)
                
                     I did a variation of "TSanchez"s method (see 1 post back)
Variation uses thermostat bypass hose as way to top off coolant... going directly into heads.
                               .......It's not really as hard as detail steps below might seem.........
           
     Method   (moderately hard....not saying it's better....just another possible way):.......

1) Look carefully at bypass hose where it attaches to thermostat housing.
                   You will be removing hose end here, and it can be trouble, if clamp is turned wrong.
                   Also, you will be re-installing a hose end and clamp here. Not much room.
2) Buy a new bypass hose: cheap and availble.  Or, alternative >
                       You can use yours, but will then also need old section of 3/4 ID hose (1 ft +/-)
3) After draining old coolant, and closing drains:
4) Remove the old bypass hose end at water pump: OR, your hose at the thermostat housing.
5) Straighten old bypass hose upward as much as you can, and tape it to the oil  filler cap   (leave oil cap on tube): OR if using your hose, install an old 3/4 in hose onto thermostat housing
      You will be pouring coolant into this hose end (thru a funnel) so hose needs to be straight up
6) Install new bypass hose at pump end (only), and straighten it enough to tape other end to      radiator hose.  If using your hose, tape it to upper radiator hose.
     You will be attaching this end to thermostat housing. You need it now to prevent coolant coming out of water pump
7) Turn HEATER CONTROL to "ON"......Do not forget this step!
8) Fill radiator with coolant.......Stop when coolant is barely above tube ends (roughly 1/4th in.)
9) Leave radiator cap OFF.
10) Fit a funnel to top of hose attached to thermostat housing, and SLOWLY, very slowly pour coolant in.
                  Do not rush pour, and hold funnel  tightly into hose.  Coolant will back up and spill.
11) Check radiator level often.  When level rises, this means no more pouring at thermostat.
12)   Hard part next:   Attach hose from water pump onto thermostat housing outlet, as follows: 
      1st:  For thermostat hose, drain hose into a small cup, and then remove hose. Have rag                          ready for spillage
      2nd: Be sure to have a hose clamp slipped onto the water pump hose, and turn clamp so it will be easy to get to.
      3rd:   Attach water pump hose onto thermostat housing. Have rag ready....spillage likely.
13) Crank engine, check hose for leaks, and watch coolant level in radiator.
14) If coolant level drops to tube level, add coolant to about 1/4th inch high.
15) If coolant level rises to 1/2-in. or more, you could boil over: Place absorbant rag into filler neck, and shutdown engine.
       
                     It took me one precautionary shutdown, which did NOT boil over.
                     At next crankup, thermostat opened.
                     Flow included small bubbles,  but no "burps"
You would need:
             a) new bypass hose.....or old 3/4th in. by 1-ft+/- hose, and clamp
             b) tools to fit hose clamps:....screwdriver....small socket
             c)  strong tape...masking....electrical....duct
             d) funnel to fit 3/4th in. hose
             e) coolant
              f) ....patience....



Edited by Lou Abernathy - Mar/26/2015 at 6:28pm

Remove bypass hose from thermo housing, fill radiator, replace hose onto thermo housing, when coolant reaches thermostat, finish filling.

Edited by 73hornut - Mar/26/2015 at 6:27pm