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Discussion Starter · #1 ·
2001 4.0

Hello, Jeep family.

First, I'm new here and want to say thank you to this community. In the 7 months I've owned this vehicle, these forums have already been a tremendous help.

I've seen similar posts to mine here, but not quite the same.

My story:

I've been smelling coolant in the cab for some time and noticed that my coolant was filthy. It looked like it may have been full of rust. Just recently, the temp started suddenly spiking into the red after getting up and sitting at about 210 degrees. I changed out my thermostat, radiator cap and just had the coolant flushed and the problem still occurs, especially at higher speeds (but I suppose that's an obvious result). I tried putting in another thermostat, thinking I may have had a bad one, but am still having the same issue. The thermostat is supposedly fail safe.

With the Jeep running and heat on, the top line to the heater core is hot and the bottom one is cold, same thing with the radiator lines, top hot and bottom cold (and not collapsed). When I run it with the rad cap off, the coolant isn't moving and eventually starts spurting out.

This leads me to believe the stat may not be opening, or that the water pump isn't working properly and could also be the cause of rusty coolant. The water pump isn't leaking or exhibiting any signs of being bad aside from the lack of circulation.

Also, while the heat was working previous to this, I did at one point see a little liquid drain down from both sides under the dash, but it stopped. I know that at some point I'll have to take on the simple (kidding) task of replacing the heater core.

Even with the heat off though, the coolant still doesn't seem to be circulating. Is this pointing to the water pump being the issue? Also, I don't know the age of the radiator.

Thoughts?

Any assistance will be greatly appreciated.
 

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When you had the radiator flushed, was it inspected to check for being clogged by anything from calcium/hard water deposits to maybe even rust?

Could be a bad water pump, are you hearing any unusual noises in the cooling system? Water pumps often get noisy before they fail.

Having installed a fail-safe thermostat won't cause the engine to overheat but nevertheless, fail-safe thermostats are NOT recommended. They tend to fail prematurely which locks them in the open position so the engine wont' warm up properly. They aren't "fail safe" by any means, that term just means when they fail they'll fail in the open position. I only recommend conventional 195 degree thermostats like from Stant. Stant's SuperStat is a great choice.

At this point my suspicions would be at the water pump or radiator. If it were my TJ, I'd make darned sure to avoid the aftermarket radiators and water pumps sold by stores like Autozone etc. and go strictly with Mopar. Pay no attention to the store's attention grabbing "lifetime warranty" on such parts which doesn't indicate good quality, it just means when it fails often and prematurely they'll give you another to waste another day on installing.
 

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Discussion Starter · #3 ·
Many thanks for the advice.

I'm in agreement that it's rad or water pump and I figure I might as well do both while its stripped down.

I don't believe they tested radiator flow when they flushed it. I think they just assumed the rad cap was the only issue since it wasn't holding proper pressure.

About a month ago I heard a whining noise from the engine bay, but it went away after a few minutes. Today, I did hear a high pitched sound during one of my test cycles. Water pump?

Thanks again.
 

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What color was the liquid dribbling down from under the dash? It sounds like your heater core is getting ready to take a crap. It would make a lot of sense to replace it at the same time.
 

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Well its fifteen years old and its a mopar. My vote would be for a waterpump. Its not uncommon. A very good flush of the system is recommended. As far as the drip under the dash and coolant smell in the cab. Sounds like heater core leaking. I myself am not a fan of the failsafe thermostat. As above poster said it can stay stuck open not allowing the motor to reach temp.
 
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