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Discussion Starter · #1 ·
Going to pose this as simply as possible;

Specs: 2004 wrangler TJ, inline 6

History: water pump, thermostat, and serpentine belt were replaced by me a few years ago. Not many miles on them but they were not easy miles I guess...radiator was replaced by me last year along with all the hoses.

Problem: initially I noticed the engine bay started chirping when I started it up in the morning. Then it started to chirp more as time went on. Then it started to squeal loudly. This is during idle and while the jeep is moving as well. I figured it was the belt. Then I started to notice the jeep was running a little hot. It got worse. It never fully overheated but it was getting there. So I deduced it was the water pump. Made sense to me but I really didn't feel like doing the thermo stat so I didn't. I drained the radiator and did the job just fine. New OEM mopar water pump! Well feeling accomplished and proud of myself with a successful install I'm finding it's still running hot but not overheating.

Side comments: the engine will start rough after it's been running hot. It will actually stall if I don't hit the gas peddle. Definitely related to the high temps, might be part of the TSB for the 3rd cylinder issue??

Solution: my next step is to replace the thermostat. I do not see why this would be broken though cause it's not overheating. But my coolant reservoir is full when the engine is hot so....I guess the thermostat isn't opening? Any other ideas? I was under the impression the engine would overheat quickly when the thermo was shot.

Thanks guys
 

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I was under the impression the engine would overheat quickly when the thermo was shot.
If the thermo is stuck fully closed, yes, but it may be only partially opening.
A new 195° Stant Thermostat is what I would do next.

(My only comment on changing the thermo is to be careful not to over-tighten, I've read horror stories of the tab on the block breaking off)
 

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For the rough idle, I'd try cleaning the IAC with the throttle body. It's not going to fix your overheating, but it may solve your rough idle so you have one less problem to worry about. If nothing else, it's good maintenance, and a possible free fix.
 

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If the thermo is stuck fully closed, yes, but it may be only partially opening.
A new 195° Stant Thermostat is what I would do next.

(My only comment on changing the thermo is to be careful not to over-tighten, I've read horror stories of the tab on the block breaking off)
X2. A Stant SuperStat 195 degree thermostat would be a good choice. Make sure to avoid installing any thermostat that says it is "fail-safe". They like to get stuck in the open position so the engine won't warm up properly.
 

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Discussion Starter · #7 ·
Thanks guys, going to try the t-stat install today. Is really like to avoid dumping all the coolant again. Can I replace the t stat without draining the radiator? Will I lose a lot? I have a mopar OEM T-stat, we'll see if it fixes it. And I'll clean out the throttle body, good call. Thanks!!
 

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You won't lose a significant amount of coolant from removing the thermostat housing but you'll need some to top it off afterwards with.

And make darned sure that Mopar thermostat has the correct 195 degree rating. My Jeep dealer's parts department has three temperature model Mopar thermostats displayed on the wall, only the 195 degree model is correct.
 

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Discussion Starter · #10 ·
Install was seamless. Old thermostat looked cheap compared to what I installed. It's running fine, no overheating. Something that concerns me now; with the heat on the engine bay has a noise that sounds like a whiny pump then clicks. Almost like a pump is sucking up water then it clicks and stops. Then 30 seconds later sucks again the clicks and stops. With the heater off it doesn't make this noise. I'd imagine this is normal but I've never noticed it, has it always been noticeable? I wonder if that's a sign something else is getting old

Btw thanks for all the help, install has been going great. I don't have a garage these days so the draining the coolant and reusing it kept things relatively clean.
 

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By chance do you have a turned off heater core in the cab? If your running a 6 inline, a clogged heater core could possibly be causing your problem. Your cooling system needs to flow, I had a hose that looked fine from the out side, but had collapsed inside, you said you burped it, I guess mopar thermostats are okay, but NAPA has Stant thermostats, I think there the best on the market, If you reuse your antifreeze be sure you strain it thru a filter, when you reinstall it, a chamois or paint filters work great, I am always amazed at the Crap that strains out of reused antifreeze. You probably already know this, but it's worth mentioning.
 

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Not sure about the whiny pump noise but one more thing I'd also change is the radiator cap with a fresh 18 lb. model replacement. A comment you made above about the coolant recovery bottle being full made me think the cap may be old and tired and letting coolant flow past it into the bottle a little too easily.

Oh just figured out what you're hearing... that's the a/c compressor clicking on & off, it runs in the defrost mode too.
 

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Discussion Starter · #13 ·
Interesting stuff, thanks guys. Yes I noticed my coolant was a bit dirty. I do offroad it. It is a hell of a lot better than when I first flushed the system for the first time last year. Jerry I did replace the cap last year with the radiator, I noticed a big difference, good catch.

My temps have been stable since replacing the thermostat. I guess it's not always a catastrophic failure when they stop working haha. We'll see how this summer goes, it's already above 70s this week. I've had the top off all week! 😎
 

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A few things to think about.

If you remove the thermostat you should never over heat.

The water pump for the 4.0 and the 4cyl look identical but the fins are in the opposite direction. So if you were given the wrong water pump you are not moving the fluid through.

I would remove the thermostat. If the problem continues I would examine the water pump.
 

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Discussion Starter · #15 ·
A few things to think about. If you remove the thermostat you should never over heat. The water pump for the 4.0 and the 4cyl look identical but the fins are in the opposite direction. So if you were given the wrong water pump you are not moving the fluid through. I would remove the thermostat. If the problem continues I would examine the water pump.
Interesting thoughts! I guess we shall see for now, if it should occur sometime soon I think your suggestion will come in handy
 

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Don't ever permanently remove the thermostat though. It's ok to run without one temporarily as a test or in an emergency but that's it. :)
 

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He has an 04 the water for the 4 banger used in 2004 was driven by the timing belt and looks nothing like the 4.0 water pump

The 2.4 four cylinder used in 2004 is based on the neon and PT cruiser transverse 2.4
 

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He has an 04 the water for the 4 banger used in 2004 was driven by the timing belt and looks nothing like the 4.0 water pump The 2.4 four cylinder used in 2004 is based on the neon and PT cruiser transverse 2.4
You right. I was thinking the 2.5. Not sure when the 2.4 went in to production
 
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