How to check for coolant flow in a Jeep 4.0L?

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Just got a 2006 Wrangler with 76,000 miles and an automatic. Previous owner just had the head gasket and radiator replaced at a shop. Temperature gauge points right between 1/2 and 3/4 marks and scan tool shows engine temp 240 to 250 on a short 5 mile drive I just drove it on, but girl I bought it from drove 3 hours here. I can see the head gasket and radiator are new and assume they would put in a new thermostat but who knows. I'm thinking the water pump may not be flowing coolant due to a broken impeller. Is there a good way to check coolant flow before removing the pump? Any suggestions what else to check? Could there be trapped air in the cooling system?
 
You may need to glove up to do it.
Grasp the upper radiator hose, apply decent grip pressure, cycle the throttle by hand, you should feel the coolant surging in the hose in time with the revs,
do it with a warmed engine/open thermostat.
 
There are two different water pumps available for the 4.0L Jeep engine. One turns right and one turns left. Put the wrong one on and you get much reduced flow. I can't remember the years though. At one time the correct direction was stamped on thee casting. Ed
 
Given the year model & low mileage....Along with it being a Chrysler product. I would just pull the water pump for a visual inspection of the Impeller (Or lack of)....Probably looks like a rusty Chinese Throwing Star by now!!!
 
The temp gauge on this engine isn't real. It's a go, no go that suddenly spikes into the red zone upon overheating. I found this out the hard way during a coolant leak! It's also mentioned in the service manual.

Temp is only accurate until warm. Then it can display anywhere below red and past half.

Personally I'd pull one of the heater hose. Do a flush cause the core is the low point and you'll be shocked at the mud that comes out. While doing the flush and filing with water on the rad side you'll see how well the pump is working.
 
As @chris142 says, the first check is to make sure the radiator is full when cold. Then start the engine cold and rev it with the radiator cap off. If bubbles or coolant blow out, the head or engine is leaking again.
 
I've been around a ton of these Jeeps ... not once have I seen a head gasket fail on a 4.0L. EVER. It's either a warped or cracked head. Some years were more prone to it than other years, but if you overheat one of these engines a few times, it's going to warp or crack the head. NOT blow the head gasket.

I have seen a lot of people change the head gasket once, twice, before getting the head checked and finding out that it warped or cracked when it was overheated.
 
Noticed some water under the engine this morning. Pressure tested it and coolant dripping from the front of the engine as well as the back where the oil pan meets the block. Assume the front is from the water pump leaking and the back is just the coolant flowing back from the front. Guess the water pump comes off next.
 
"240-250? Yikes"

When I had my 4.0, normal temps were 212 - 219.

Eventually, I got tired of it getting hot during the summers, so I had a Spectra 3-core radiator installed in it. Changed out the thermostat to 180 degree (some people say just use the 195) and flushed with new coolant.

Stayed at 210 or below after that. Then I sold it 2 months later....waaaa
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GL
 
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these are durable engines and can handle a lot of abuse, including overheating. Just go through the normal things. Pump, T-stat, leaks. The leak on the back concerns me some.

I bought an old one with a warped head - oil and coolant literally seeped down the side of the block where the head met the block. I torqued the head 25lbs over and that cut the leakage down to 1/3 of what it had been, and kept driving it.
 
Started taking things apart. Radiator does look new.

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Put in a new Stant Superstat 180 degree thermostat.

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You can see a new valve cover gasket and head gasket.

Took the water pump off and it wasn't replaced but seemed fine. It wasn't the original Mopar pump either and the gasket area was pretty messed up so that's probably where the leak was coming from. Ordered a new OEM pump from Chrysler. Expensive.
 
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