Jeep Cherokee overheating

[jasoneggleston]

94 Jeep Cherokee 6 cyl 4.0l

I forgot that I had water in the radiator. One morning after a cold night I came outside to discover it had frozen a bit. Not too serious but still had some ice in it. The bottom radiator house was also disconnected.

I drained all the water, replaced the bottom hose and filled with antifreeze.

Jeep had no heat and was overheating so I changed the thermostat.

Still was overheating so I parked it in a heated garage for 24hours to let anything that might be frozen thaw.

Came back to it today and it was still overheating.

I took the radiator out and water seems to flow threw it fine. I flushed the heater core. I ran water thew the motor and it seemed to flow fine.

I hooked it all back up without the thermostat and it got to about 225 degrees and stayed there for about 30mins. I drove it to the part store, got a new thermostat and installed it. Filled it with new antifreeze and it overheated almost immediately.

Can anybody offer any ideas what it could be?

Also, it does not seem to be related to any head problems.

[Scrapper]

when you done all that did you fill it back up while it was running? but sounds like head gasket or gaskets. try this pull plugs see if there wet with antifreeze if so head or gasket or both. i've seen alot that some people wait until it's to late on winter rising there vehicle. not saying you did but you said water was frozze. i doubt the block is cracked but you never know. but yah pull plugs take a look and look in your oil and see if it looks milky? if so not good.....

good luck.........

[jasoneggleston]

Thanks for the quick reply.

I did check the plugs and oil for any signs of head gasket problem but didnt notice anything.

[shorod]

There's a good chance you have an air pocket in the cooling system that is causing a lack of heat and possibly incorrect readings on the gauge. Did you confirm the engine is actually getting really hot, or is there a chance the sensor is bad or disconnected? Since it's showing that it's overheated "almost immediately" it sounds like the gauge is not accurately displaying the actual coolant temperature.

-Rod

[jasoneggleston]

Originally Posted by shorod

There's a good chance you have an air pocket in the cooling system that is causing a lack of heat and possibly incorrect readings on the gauge. Did you confirm the engine is actually getting really hot, or is there a chance the sensor is bad or disconnected? Since it's showing that it's overheated "almost immediately" it sounds like the gauge is not accurately displaying the actual coolant temperature.

-Rod

I am pretty sure that I do not have air in the system. It has been completely drained and refilled a couple times now.

The engine is actually getting hot. It is not an inaccurate reading.

[shorod]

Originally Posted by jasoneggleston

I am pretty sure that I do not have air in the system. It has been completely drained and refilled a couple times now.

That is exactly how you get air trapped in the system. Following a drain and refill you often need to purge the cooling system to get the trapped air out. Some models even have a purge valve specifically for this purpose.

-Rod

[HeavyJ]

If you think there is air in the system, pull the front wheels up on some ramps, then let it idle while watching the fill neck on the radiator. If there is air, it will burp it and you can add coolant.
After it gets hot, with the engine off, can you feel the radiator and see if its hot also? Feel the core in several places. With the rad cap off, is it circulating coolant? When the thermostat opens, you should feel coolant being pumped through the hoses.