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How to check for coolant flow in a Jeep 4.0L? #5143176 06/24/19 07:51 PM
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atikovi Offline OP
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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?

Re: How to check for coolant flow in a Jeep 4.0L? [Re: atikovi] #5143191 06/24/19 08:04 PM
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Warstud Offline
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How well does the heater work?

Re: How to check for coolant flow in a Jeep 4.0L? [Re: atikovi] #5143192 06/24/19 08:05 PM
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vw7674 Offline
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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.

Re: How to check for coolant flow in a Jeep 4.0L? [Re: atikovi] #5143210 06/24/19 08:35 PM
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Chris142 Offline
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If the heater works the pump is working.


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Re: How to check for coolant flow in a Jeep 4.0L? [Re: atikovi] #5143217 06/24/19 08:42 PM
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Eddie Offline
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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


2014 CX5 Touring 2.5L :-)
Re: How to check for coolant flow in a Jeep 4.0L? [Re: atikovi] #5143260 06/24/19 09:41 PM
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clinebarger Offline
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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!!!


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Re: How to check for coolant flow in a Jeep 4.0L? [Re: atikovi] #5143263 06/24/19 09:46 PM
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atikovi Offline OP
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Had the A/C on, will check the heat tomorrow, thanks.

Re: How to check for coolant flow in a Jeep 4.0L? [Re: atikovi] #5143277 06/24/19 10:02 PM
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Chris142 Offline
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They can be a little time consuming to get the air bled out. But since its been ran a few times if you check the coolant in the radiator when its cool and its full its OK.


02 Wrangler Napa high milage 10w40
87 F250 Valvoline 15w40
07 fjcruiser Car lube plus 10w30
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Can am Maveric edge 5w40
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Re: How to check for coolant flow in a Jeep 4.0L? [Re: atikovi] #5143339 06/25/19 12:12 AM
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DoubleWasp Offline
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240-250? Yikes. Methinks head gasket repair failed.


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Re: How to check for coolant flow in a Jeep 4.0L? [Re: atikovi] #5143352 06/25/19 12:45 AM
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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.

Re: How to check for coolant flow in a Jeep 4.0L? [Re: atikovi] #5143443 06/25/19 06:12 AM
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mk378 Offline
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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.

Re: How to check for coolant flow in a Jeep 4.0L? [Re: atikovi] #5143450 06/25/19 06:25 AM
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Miller88 Offline
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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.


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Re: How to check for coolant flow in a Jeep 4.0L? [Re: atikovi] #5143780 06/25/19 12:54 PM
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atikovi Offline OP
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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.

Re: How to check for coolant flow in a Jeep 4.0L? [Re: atikovi] #5143793 06/25/19 01:05 PM
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mk378 Offline
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I'd do the block leak check before spending any more money on the thing.

Re: How to check for coolant flow in a Jeep 4.0L? [Re: atikovi] #5143823 06/25/19 01:40 PM
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Greg L Offline
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"240-250? Yikes" <-----This


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 frown


GL



Last edited by Greg L; 06/25/19 01:41 PM.

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