xjsnake

The thermostat should have a little hole in it on the metal flange part. This hole should be at 12 O'clock when installed and it will automatically bleed the air from the system as the engine runs.

LongArmXJ

all t stats? i got mine from autozone and i didnt pay any attention when i put it in. hmm..

djb383

T-stats don't seal water or air tight when closed but if the t-stat does have a bleed hole, place at 12 o'clock. With the motor COLD, I'd be removing the rad cap for the next several days to check the coolant level. U've got to have a properly functioning rad cap as it's a 2 way valve and maintain coolant levels in both the rad and bottle. If u have any leaks, air gets sucked inside the system as the motor cools. Read my sig.

LongArmXJ

i raise my hood more than once a week lol. and the cap is new. radiator is new, t stat and water pump. i keep an eye on my fluids, i just want heat! im letting it cool down right now then ill check levels and try bleeding again... and again and again

xjsnake

Last time I got an autozone thermostat for an XJ it didn't have a hole in it. I ended drilling one in it. Probably should have gone and gotten one with a hole already but I knew where to drill it.

LongArmXJ

this will be my second time running till warm w no cap, shut off cool down top off. the heat has gotten a little warm and each time i have done it the radiator has taken in fluid. im hoping this is going to work. now time to get some coolant in there and do it all over again. i just want to be sure this is the issue before i go wasting good coolant. ill keep this up dated. i have to run to autozone in a minute im going to ask to see the one i bought to see if it has a hole in the t stat. so i know. updates to come....

LongArmXJ

ran up to auto zone and looked at the thermostat i bought and there is no hole. could have an effect on why its being so hard to bleed. I have since burped it two more times and the heat is getting warmer. ill post a final update once its hot heat but im going to guess i had a bunch of air trapped. the entire time that i have been burping the system i have had the driver side jacked up.

djb383

Air and water will bleed by/thru the t-stat the moment the motor starts. U've done the initial air bleed by letting it idle with the rad cap off. '91 and up are self-bleeding cooling systems. Be sure to install a NEW rad cap.....it's a 2 way valve. It allows coolant to escape to the bottle when the motor heats up and allows coolant to flow back to the rad when the motor cools. U should see the coolant level rise a little in the bottle (motor hot) and fall a little (motor cold). Remove the rad cap, COLD motor, for several days in a row to check coolant level and check it weekly thereafter.

If your heater is not working, hot coolant is not flow thru the heater core or the flapper door on the heater box under the dash is not opening/closing correctly or both.

Could your water pump look like this?....no impeller blades left....over the top owner neglect.

LongArmXJ

i have burped it again and its getting warmer. i must have some air in there that doesnt want to come out. ill keep checking fluids and hope it continues to get warmer not COLDER

djb383

I'm puzzled why u think u r heater problem is still 'air in the system' problem vs a 'coolant flow thru the heater core and/or flapper door problem'? '91 up are self-burping.

LongArmXJ

its getting warmer each time and it is letting out quite a bit of air and taking fluid in. what do you suggest it to be? and how would you go about checking it? it seems to be getting better. if it were a flapper door or what ever would i get heat at all? what would be a good way to check its flow throught the heater? pull a hose off and start?

LongArmXJ

if there is air in the sys in some cases your heat wont be warm. i changed the water pump on a grand am once and didnt get the air all out and had no heat. got all the air out and heat was hot.

djb383

Air always makes its way to the highest point. If coolant is low enough to be below the heater core inlet hose, then hot coolant won't properly reach the heater core. Granted, if coolant is that low, the motor probably overheats also. That's why I've suggested checking the coolant level in the rad, motor COLD, be checked for the next several days and weekly thereafter. If the rad does not stay full to the top after several days, u have a leak or bad rad cap. The bottle must always have some coolant in it. If the bottle goes dry, air enters the system.

Ashewagon

I am having the same problem with my 94. Heat worked great till I rebuilt the engine. Now I have a little heat then it goes cold. New thermostat and heater control valve. I will start the same process of bleeding and see if it works for me.

thanks

xjsnake

This is good advice. The only caveat is the bleeder hole in the the thermostat flange allows the air to reach the highest point much faster and usually without manual bleeding.