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How to check for coolant flow in a Jeep 4.0L? #5143176
06/24/19 08:51 PM
06/24/19 08:51 PM
Joined: Apr 2010
Posts: 1,718
Suburban Washington DC
atikovi Online content OP
atikovi  Online Content OP

Joined: Apr 2010
Posts: 1,718
Suburban Washington DC
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 09:04 PM
06/24/19 09:04 PM
Joined: Sep 2005
Posts: 6,474
MIchigan
Warstud Offline
Warstud  Offline

Joined: Sep 2005
Posts: 6,474
MIchigan
How well does the heater work?

Re: How to check for coolant flow in a Jeep 4.0L? [Re: atikovi] #5143192
06/24/19 09:05 PM
06/24/19 09:05 PM
Joined: Feb 2019
Posts: 141
WA
vw7674 Offline
vw7674  Offline

Joined: Feb 2019
Posts: 141
WA
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 09:35 PM
06/24/19 09:35 PM
Joined: Jun 2003
Posts: 19,177
Apple Valley, California
Chris142 Offline
Chris142  Offline

Joined: Jun 2003
Posts: 19,177
Apple Valley, California
If the heater works the pump is working.


02 Wrangler traveler sae30
87 F250 Valvoline 15w40
07 fjcruiser Chevron 10w30
Z400 castrol T 10w40
Can am maveric edge 5w40
57 case tractor Chevron sae30
Re: How to check for coolant flow in a Jeep 4.0L? [Re: atikovi] #5143217
06/24/19 09:42 PM
06/24/19 09:42 PM
Joined: Dec 2003
Posts: 10,346
Florida, Cape Coral
Eddie Offline
Eddie  Offline

Joined: Dec 2003
Posts: 10,346
Florida, Cape Coral
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 10:41 PM
06/24/19 10:41 PM
Joined: Dec 2013
Posts: 3,362
Fort Worth, Texas
clinebarger Offline
clinebarger  Offline

Joined: Dec 2013
Posts: 3,362
Fort Worth, Texas
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!!!


2001 Chevy Camaro L92/4L80E
2006 Chevy 2500HD LBZ/Allison 1000
2010 Toyota Corolla 2ZR-FE/U341E
2000 Toyota Avalon 1MZ-FE/A541E
Re: How to check for coolant flow in a Jeep 4.0L? [Re: atikovi] #5143263
06/24/19 10:46 PM
06/24/19 10:46 PM
Joined: Apr 2010
Posts: 1,718
Suburban Washington DC
atikovi Online content OP
atikovi  Online Content OP

Joined: Apr 2010
Posts: 1,718
Suburban Washington DC
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 11:02 PM
06/24/19 11:02 PM
Joined: Jun 2003
Posts: 19,177
Apple Valley, California
Chris142 Offline
Chris142  Offline

Joined: Jun 2003
Posts: 19,177
Apple Valley, California
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 traveler sae30
87 F250 Valvoline 15w40
07 fjcruiser Chevron 10w30
Z400 castrol T 10w40
Can am maveric edge 5w40
57 case tractor Chevron sae30
Re: How to check for coolant flow in a Jeep 4.0L? [Re: atikovi] #5143339
06/25/19 01:12 AM
06/25/19 01:12 AM
Joined: May 2012
Posts: 6,709
Fort Lauderdale, FL
DoubleWasp Offline
DoubleWasp  Offline

Joined: May 2012
Posts: 6,709
Fort Lauderdale, FL
240-250? Yikes. Methinks head gasket repair failed.


07 Lincoln Navigator M1 0w-40/FU
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07 Ram 3500 4x4 / Cummins 6.7 /DBL7349
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Re: How to check for coolant flow in a Jeep 4.0L? [Re: atikovi] #5143352
06/25/19 01:45 AM
06/25/19 01:45 AM
Joined: Jun 2017
Posts: 222
NY
DdDd Offline
DdDd  Offline

Joined: Jun 2017
Posts: 222
NY
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 07:12 AM
06/25/19 07:12 AM
Joined: Sep 2015
Posts: 1,937
USA
mk378 Online content
mk378  Online Content

Joined: Sep 2015
Posts: 1,937
USA
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 07:25 AM
06/25/19 07:25 AM
Joined: Apr 2008
Posts: 13,416
Central NY
Miller88 Offline
Miller88  Offline

Joined: Apr 2008
Posts: 13,416
Central NY
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.


18 Forester 2.5I 6M
00 Jeep XJ
01 F-350 4x4 5M
Re: How to check for coolant flow in a Jeep 4.0L? [Re: atikovi] #5143780
06/25/19 01:54 PM
06/25/19 01:54 PM
Joined: Apr 2010
Posts: 1,718
Suburban Washington DC
atikovi Online content OP
atikovi  Online Content OP

Joined: Apr 2010
Posts: 1,718
Suburban Washington DC
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 02:05 PM
06/25/19 02:05 PM
Joined: Sep 2015
Posts: 1,937
USA
mk378 Online content
mk378  Online Content

Joined: Sep 2015
Posts: 1,937
USA
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 02:40 PM
06/25/19 02:40 PM
Joined: May 2006
Posts: 710
N. Calif - State of Jefferson
Greg L Offline
Greg L  Offline

Joined: May 2006
Posts: 710
N. Calif - State of Jefferson
"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 02:41 PM.

1951 GMC 1/2 Ton 270ci
2008 Jeep Compass 2.4
2010 Toyota Prius 1.8
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