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Charging cooling system
Posted: March 13th, 2012, 7:57 am
by Grego
Does anyone pre add any coolant to the head before closing up the system and filling the radiator and reservoir. I read a few articles on here about filling the radiator the night before to burp out air, but is there anything else everyone does before hand with the cooling system before initial starup and breakin.
Thanks, Greg
Re: Charging cooling system
Posted: March 13th, 2012, 11:18 am
by Retlaw01XJ
Drill a 1/4" hole in the thermostat and position the hole at the top. That will at least allow air to bleed out when you are filling the system. leave the upper heater hose off and you can see when it's filled to that level. I've read of some who raise the front of the Jeep to help purge air out, but I'm not familier with the early ones, just my 2001.

Re: Charging cooling system
Posted: March 13th, 2012, 7:28 pm
by IH 392
A 1/4" hole is to big, a 1/16" hole will do fine, in fact most thermostats have a "bleed" notch in them it can be seen with a close look, a hole just speeds up the bleed, if you pull the heater hose off of the thermostat housing or the coolant temp sensor the air will bleed in a hurry!
Re: Charging cooling system
Posted: March 14th, 2012, 5:26 am
by 92tank
IH 392 wrote:A 1/4" hole is to big, a 1/16" hole will do fine, in fact most thermostats have a "bleed" notch in them it can be seen with a close look, a hole just speeds up the bleed, if you pull the heater hose off of the thermostat housing or the coolant temp sensor the air will bleed in a hurry!
pulling the heater hose off the thermo houseing doesnt do to much from my experience, as its still in front of the thermo. the best i have found is fill the rad before putting the thermo on and filling to just before coolant comes out then you only have a little air in the head (but that will come out once the thermo opens). then put the thermo in and hook up the hoses, top off the rad, start and bring up to temp and check the coolant level again