Air pockets in radiator....

I don't know if this is from the extreme cold Ohio has been getting but I keep getting air pockets in my cooling system (95 XJ) I won't get heat unless I give it throttle. I burped it last month and it worked fine until today. The radiator was flushed and thermo replaced less than 1 year ago, I've never had this problem with my 92. Whats the deal???

The way I've always burped it is to have someone hold the throttle to about 3,000rpm while I top it off then put the cap on before the throttle is released....this method allows you to get about a quart more coolant.

Hallo. I don't think there are air pockets in the radiator.
Mostly you have to pinch the upper waterhose with both hands when warm.(like pumping)
It works always by my '92.........

Is it using coolant?

winterbeater said:

Is it using coolant?

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when you say using do you mean leaking?? if so no it does not leak

isnt the open system self burping? if you have to rev the engine i would look at flow as being the problem, but not air cuasing the flow problem. could be a bad water pump or clogged heater core.

jeepman121 said:

when you say using do you mean leaking?? if so no it does not leak

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Do you have to add coolant on a steady basis? ie. need some every day or every week, in other words, Is coolant disappearing?

The 95 XJ do not need purging if the cooling system is in good working order or any other time for that matter. If you have to rev the engine to get heat inside the cab, it seem to indicate there may be low level coolant I must admit. There are a number of things that you need to do to remedy this.

1) Leaks. Are you loosing coolant? Check for leaks and fix them.

2) The pressure cap. Check that the cap is fitting correctly. With the engine at proper opreating temperature, squeeze the radiator hose it should be firm. Just having a new cap or new radiator do not of itself guarantee they are fitting and sealing properly.

3) Fill the radiator when cold. Fill the recovery tank above the full mark. Now is a good time to check the hose between the radiator and the recovery tank from end to end including the ends on the radiator and the tank itself. It should seal tightly at both ends.

4) Move the selector lever of the in-cab heater to the hottest setting and the heater fan on high speed. Run the engine until it reaches operating temperature. Shut it down and leave it to cool off. ( When the engine is hot, excess coolant may pass from the radiator into the recovery tank. That is how it should work.) When the engine cools/is cold, add coolant to the recovery tank as needed.

I had both a '94 and a '96 4.0L and never had to burp any of them.

Hope this helps.

As Techno 1154 pointed out above, that hose from radiator to recovery tank (RT), MUST be in good condition and secure. ** (If any doubt, just replace it)**
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Easy test- (Do Not Open radiator cap, If Opened -Start Over)

-With cold engine, full coolant, and RT level between 'add' and 'full' marks- Make note of 'Cold' RT level, warm-up engine to operating temperature, note the 'Hot' RT level rises (about 1 inch, more or less). Now let it all cooldown overnight or a few hours. RT level will go back to 'Cold' RT level.
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If there is air in system it will go out thru the recovery tank and RT level will go down next cooldown as coolant is pulled back to engine.
Add coolant to Recovery Tank, as needed, to stay between Full And Add marks. ***Again, Do Not Open Radiator Cap-if opened, Start Over!***


*IF RT Level is Not changing hot to cold-- FIX IT-- There is a problem! (Somewhere there is a air leak.)

Good Jeepin,
orange

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Have you checked the heater control valve to make sure it is functioning properly? Possibly only partially opening, thereby only letting enough coolant through under throttle when there's more pressure?

have not checked that....I'm thinking it could be that since the Jeep only has these fusses every now and again. It has worked fine since I've posted this. Also...I never have fluid in my recovery tank, and I never had any issues I didn't think they mattered that much???

If you don't have fluid in your recovery tank, you don't have enough fluid. There are full and add marks that you should try to observe, but you at least need to see some coolant in the bottom of the tank ALWAYS.

I have a 92 that always had a dry return tank....must have been lucky I guess

jeepman121 said:

I have a 92 that always had a dry return tank....must have been lucky I guess

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dry overflow tank is not good. when the system expands, coolant goes into overflow tank, when system contracts, it pulls from the overflow. yours may be pulling in air instead of coolant.

Hallo jeepman 121.
special for you a pic of a coolant bottle (filled) of a '92 XJ,

yeah you obviously had air in the system. Thats why reving it got enough coolant to fill the heater hoses and heater core and thus give you heat. You let off the gas and the air just gets sucked back to that area. With air in that heater hose or trapped in the heater core itself you wont get heat.
Once youve topped of your overflow bottle that should be it (In theory) as you shouldnt need to burp your system because it self burps, But im convinced that it does NOT do this 100 percent of the time and i would burp it again until you were satisfied that your system has no air in it.

got it...thanks fellas!!

89xj said:

dry overflow tank is not good. when the system expands, coolant goes into overflow tank, when system contracts, it pulls from the overflow. yours may be pulling in air instead of coolant.

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Bingo!!! You hit the jackpot. Something is alwas in the recovery tank,...air, water or both. I always make sure my XJ recovery tank is is at the full level when cold.