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Over heating problem


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Trying to sell my MJ and it would be alot easier if i could fix the overheating problem. Here is what i have done so far...

 

Replaced:

Fan Shroud

Overflow Tank

Thermostat

WaterPump

Hoses and clamps

 

Its spewing out at the overflow tank at the top outlet. Did this on the old tank and is doing it again on the new one. Help!

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Is the fan working?

 

If electric, is it running at all?

 

If mechanical, is the clutch okay?

 

Could also be a plugged radiator, or a cracked head gasket.

 

Mechanical Fan works fine. How do I "unplug" the radiator? Head gasket sounds fun.

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A pressure test will tell you if the radiator is good or not. If it is plugged up, you can have a radiator shop ream it out, or you can replace it,

 

If you're being a smart alec, ignore this reply.

 

No, I'm being serious and I appreciate your input brotha.

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If this has ac check to see if mud is packed inbetween the condesor and rad. this was a prob on my brothers XJ. You also might try flushing the radiator, but I am not sure this would help. Overheating is a *&%^$ :mad: It could be 1000 different things.

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That system is VERY sensitive to air in it. Did you properly bleed the air out of the system when you changed these parts?

 

The problem you are describing sounds like the same issue I had when I did similar work and found out about the bleeding thing as I had never dealt with a closed cooling system before.

 

replace the cap on the rad
FYI... Closed system...it doesn't have a cap unless it's been converted, but since he said it was blowing out of the bottle, doesn't sound like it's converted to me ;) .
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That system is VERY sensitive to air in it. Did you properly bleed the air out of the system when you changed these parts?

 

The problem you are describing sounds like the same issue I had when I did similar work and found out about the bleeding thing as I had never dealt with a closed cooling system before.

 

replace the cap on the rad
FYI... Closed system...it doesn't have a cap unless it's been converted, but since he said it was blowing out of the bottle, doesn't sound like it's converted to me ;) .

 

No, i havnt bled any air out of it. How do i do such a thing?

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With the back of the truck higher than the front. Start the engine and let it heat up some. Unscrew the temperature sender located on the driver's side of the head close to the valvecover gasket ( somebody ad a picture please.) when the air bubbles stop coming out and you only get coolant screw the sensor back in . Your done.

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Yep...that's it.

 

Don't get the engine too hot though or you won't be able to get your hands in there to remove & repalace that sensor. Mine was nearly completely cooled when I did it. The important thing is to have the front of the truck lower than the back so the air will all go to the rear of the head and out the sensor hole. Be sure that your plastic bottle has plenty of fluid in it as well.

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i scanned through but i don't think anyone mentioned.

 

that bottle isn't (shouldn't be) an overflow it should be a pressure bottle with a pressure cap on it. check the cap, and if you didn't get a pressure bottle try replacing it with one from the dealer.

 

i think the cap is like 9 bucks through mopar.

 

and check the temp of the engine with a laser gun! the gauge may be lying to you!

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i scanned through but i don't think anyone mentioned.

 

that bottle isn't (shouldn't be) an overflow it should be a pressure bottle with a pressure cap on it. check the cap, and if you didn't get a pressure bottle try replacing it with one from the dealer.

 

i think the cap is like 9 bucks through mopar.

 

and check the temp of the engine with a laser gun! the gauge may be lying to you!

 

It is a pressure bottle with the pressure cap.

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  • 1 month later...

On the sensor...do i unscrew just the little screw part or the whole thing with a socket?

 

I just did it with the little thin screw out and nothing came out, just started over heating again.

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