2000 4.0L Cooling System Issues - JeepForum.com
 6Likes
Reply
 
LinkBack Thread Tools
post #1 of 75 Old 09-13-2017, 09:08 AM Thread Starter
Marleyx1981x
Registered User
2000 TJ Wrangler 
 
Join Date: Jul 2017
Location: Houston
Posts: 16
2000 4.0L Cooling System Issues

Hi everyone,

My 4.0 (new to me) had some ugly coolant, so I decided to change it. Never had overheating issues. Temperature needle would, at worst, touch the higher side of 210F (likely around 210, per my OBDII).

I drained the fluid and filled with distilled water several times before finally replacing the old thermostat (195F Motorad) with a Mopar 195F, filling with Zerex G-05, and installing a new radiator cap (18 psi).

In the process of burping the system, I left the radiator cap off until operating temp, and noticed my heater wouldn't work unless my radiator cap was on. The water pump heater hose was bone cold unless I had it on.
So, that was sorted to my knowledge.

Driving on the freeway was perfect. Once in high speed stop and go (drive half a mile at 45 mph, then hit a stoplight for 2 or 3 minutes), I noticed my temperature creeping up. I oberseved this several times. It would get to 220-230. This is after a while of stop and go with AC on. For the first 30 minutes, I'd see 205F pretty consistently.

One day, when completely cold, I opened the radiator cap and some pressure released and spilled fluid. I put the cap back on, and drove some short drives with no issues.

Another day, during extended stop and go, I got up to 220F again.

When I would hit these temperatures, I'd turn the AC off and it would be totally fine, dropping back to 205F in about 2 to 3 minutes.

Got my mechanic to look at it, he suggested I replace my radiator, so I did; it had some noticeable rust on the tubes and outside of the core. He suggested a 180F thermostat which I have in now. Has fresh coolant as well.

Now I understand using a low temperature thermostat has its problems, and I'm not a fan of this.
My question is, do you think my water pump could be causing these issues?

Fan clutch operates properly per some quick tests I did.
Mechanic doesnt susppect combustion leaks, and I have no symptoms. I also ran a successful compression test before buying the Jeep about 2 months ago.

Of course the Jeep runs colder on shorter drives, and colder than before, but it still seems to have an uncontrolled creep up in stop and go traffic.

2000 TJ, 4.0, 136k miles, 0331 cyl head

Marleyx1981x is offline  
Sponsored Links
Advertisement
 
post #2 of 75 Old 09-13-2017, 10:28 AM
Shark_13
Registered User
1998 TJ Wrangler 
 
Join Date: Dec 2012
Location: Post falls
Posts: 1,203
You should have stayed with the 195F thermostat.

Did you burp the system after refilling? Some will chime in to say the system is self burping, but many others, including myself, have had air bubbles tried, until squeezing the rad hose a handful of times with the cap off.
If the system fluid was in poor shape initially, the water pump may need replacing.

How is the fan clutch?
Shark_13 is online now  
post #3 of 75 Old 09-13-2017, 10:33 AM Thread Starter
Marleyx1981x
Registered User
2000 TJ Wrangler 
 
Join Date: Jul 2017
Location: Houston
Posts: 16
I agree with the 195F thermostat.

The fan clutch appears to be working properly.

I guess my question is two-fold: how stable should I expect my temps to be at full operating temp, and is there any way to diagnose the water pump not flowing properly without removing it?
Marleyx1981x is offline  
 
post #4 of 75 Old 09-13-2017, 11:09 AM
TJnBC
Registered User
2006 LJ Wrangler 
 
Join Date: Mar 2010
Location: Vancouver
Posts: 1,337
Put back the 195F thermostat.

Go get a NEW rad cap 18lbs. Bleed the system again. I had similar symptons a couple weeks ago and a new rad cap and proper bleed solved it.

2006 LJR...the madness begins again
TJnBC is offline  
post #5 of 75 Old 09-13-2017, 01:09 PM Thread Starter
Marleyx1981x
Registered User
2000 TJ Wrangler 
 
Join Date: Jul 2017
Location: Houston
Posts: 16
Also, I did burp it. I let it warm up without the radiator cap. Might not be extensive enough.
Marleyx1981x is offline  
post #6 of 75 Old 09-13-2017, 01:34 PM
TJnBC
Registered User
2006 LJ Wrangler 
 
Join Date: Mar 2010
Location: Vancouver
Posts: 1,337
Quote:
Originally Posted by Marleyx1981x View Post
Also, I did burp it. I let it warm up without the radiator cap. Might not be extensive enough.
Do it again...pop your Heat in the cab on FULL blast ...not until you reach the normal operating temperature should you put that cap back on. Typically I let it get to operating temp, let the bubbles , bubble over into a bucket (you may need to add as it overflows). Then once you can feel upper rad hose hot AND the bubbles stop, put the NEW cap back on.

Are you using ONLY distilled water? 50/50 mix ? or Mixing straight Antifreeze with distilled? don't just use Distilled....

2006 LJR...the madness begins again
TJnBC is offline  
post #7 of 75 Old 09-13-2017, 02:46 PM Thread Starter
Marleyx1981x
Registered User
2000 TJ Wrangler 
 
Join Date: Jul 2017
Location: Houston
Posts: 16
I used 1.25 gal of 100% coolant after my distilled water flushes then topped off with distilled (there was distilled water still in the cooling system). Really I'm hoping to hear people's opinions on poor water pump and fan clutch behavior. I'm having great results on non-traffic drives.
Marleyx1981x is offline  
post #8 of 75 Old 09-13-2017, 03:04 PM
Jerry Bransford
Administrator
 
Jerry Bransford's Avatar
2004 TJ Wrangler 
 
Join Date: Jan 2003
Location: Escondido, California
Posts: 69,061
First, the TJ's cooling system absolutely will self-burp itself of any trapped air by doing nothing but driving.

A good fan thermostat will be very stiff and hard to turn by hand when everything is good and hot.

Hard to diagnose a bad/weak water pump but if it hasn't been changed by now, a 2005 pump is likely on its last legs by now. Make sure to install a Mopar if you can find one. At the very least avoid store-brand water pumps from low-end auto parts stores like Autozone.

And I'd stop going to a mechanic clueless enough to have replaced the proper 195 degree thermostat with a 180 degree model in an attempt to stop it from running too hot. If he knew what he was doing he'd know that going with a lower temperature thermostat cannot force the cooling system to run cooler. If it could we could switch to 100 degree thermostats and only need a very small radiator.

A thermostat's only function is to set the engine's minimum operating temperature in cold conditions and to help it warm up faster. It will NOT cause or help an overheating engine to run cooler when the currently installed thermostat is functioning properly.
numchuck and DmfHiggins like this.

When you have a choice, buy American made.
Jerry Bransford is offline  
post #9 of 75 Old 09-13-2017, 04:13 PM
TJnBC
Registered User
2006 LJ Wrangler 
 
Join Date: Mar 2010
Location: Vancouver
Posts: 1,337
Quote:
Originally Posted by Marleyx1981x View Post
I used 1.25 gal of 100% coolant after my distilled water flushes then topped off with distilled (there was distilled water still in the cooling system). Really I'm hoping to hear people's opinions on poor water pump and fan clutch behavior. I'm having great results on non-traffic drives.
I had the EXACT same issues as you. To a tee. Hwy drives no problem , even at traffic ALL year I was fine. Until one day it was climbing temp sitting in traffic for 2-4minutes.

I replaced the rad cap (18lbs) and no more issues at all. Start with something cheap and simple ($6) and go from there.

2006 LJR...the madness begins again
TJnBC is offline  
post #10 of 75 Old 09-13-2017, 04:41 PM
TheBoogieman
Disturbed Jeepaholic
 
TheBoogieman's Avatar
2003 TJ Wrangler 
 
Join Date: Aug 2006
Location: CharlottesHELL
Posts: 35,719
Quote:
Originally Posted by TJnBC View Post
I had the EXACT same issues as you. To a tee. Hwy drives no problem , even at traffic ALL year I was fine. Until one day it was climbing temp sitting in traffic for 2-4minutes.

I replaced the rad cap (18lbs) and no more issues at all. Start with something cheap and simple ($6) and go from there.
X 2.

Quote:
Originally Posted by jeepinmichguy_ View Post
TheBoogieman is a jerk.
Quote:
Originally Posted by mrblaine View Post
Why also would he need a rare as hen's teeth Dana 44 out of another TJ which will eventually lead to him swapping in a POS 8.8 because he can't find one?
TheBoogieman is offline  
post #11 of 75 Old 09-13-2017, 07:17 PM
Pine_Cat
Senior Member
 
Pine_Cat's Avatar
2006 TJ Wrangler 
 
Join Date: Nov 2012
Location: Voorhees
Posts: 952
Quote:
Originally Posted by Jerry Bransford View Post
And I'd stop going to a mechanic clueless enough to have replaced the proper 195 degree thermostat with a 180 degree model in an attempt to stop it from running too hot. If he knew what he was doing he'd know that going with a lower temperature thermostat cannot force the cooling system to run cooler. If it could we could switch to 100 degree thermostats and only need a very small radiator.

A thermostat's only function is to set the engine's minimum operating temperature in cold conditions and to help it warm up faster. It will NOT cause or help an overheating engine to run cooler when the currently installed thermostat is functioning properly.
Thanks, it's great to hear some logic, not much of that outside of JF.

OK4WD insisted that a 160-degree thermostat would help, installed it without authorization. They also insisted that the factory cooling system can not be made to work with a well-maintained 4.0L. Insisted that an all-metal radiator and e-fan are necessities (why me ?!?).

Most small shops I've been to professed to be of the same opinion, so I wonder if this is more scam than misunderstanding?

2017 JK Sahara (my Smart car)
2011 KK Liberty (H&R lift springs, OldManEmu shocks/struts, skinny 32s)
2009 Kia Sorento (H&R springs, ToyTec strut spacers, OldManEmu shocks/struts, skinny 31s)
2006 TJ budget LCG prerunner (see profile)
2006 Chevy Trailblazer (SWB-EXT lift, rear LJ Nth 4.5" springs, skinny 32s)
1998 Dodge Durango (SuspensionMaxx and Roadmaster lifts, rear Truetrac, skinny 32s)
Pine_Cat is offline  
post #12 of 75 Old 09-13-2017, 10:21 PM
Shark_13
Registered User
1998 TJ Wrangler 
 
Join Date: Dec 2012
Location: Post falls
Posts: 1,203
They just want to sell you more parts.
Shark_13 is online now  
post #13 of 75 Old 09-14-2017, 06:50 AM
mrblaine
Wizard of Brakes
 
mrblaine's Avatar
1999 TJ Wrangler 
 
Join Date: Dec 2004
Location: Quail Valley
Posts: 31,795
Quote:
Originally Posted by TJnBC View Post
Do it again...pop your Heat in the cab on FULL blast ...not until you reach the normal operating temperature should you put that cap back on. .
What does that do? The TJ heater core gets full circulation of engine coolant regardless of the position of the blend door, so what does running the blower motor do for you?

I am Savvy
blackmagicbrakes.com
Knowledge does not equal understanding.
mrblaine is offline  
post #14 of 75 Old 09-14-2017, 07:46 AM Thread Starter
Marleyx1981x
Registered User
2000 TJ Wrangler 
 
Join Date: Jul 2017
Location: Houston
Posts: 16
I understand the thermostats operation pretty well now, I think. I definitely agree it will only lower the minimum temperature.

Before I change anything, I'd like to see if I can really suss out the problem. I've got plenty of time on my hands (I don't daily this rig), certainly more time than money to spend.

I drove around for an hour or so last night, logging coolant temp along the way to graph it. I observed, of course, a lower operating temp (read: too low) in the beginning. I made sure to hit some stop and go traffic. Temperature got to just under 210F in some instances. When I got moving, however, I noticed it would drop down to 185F again.

I think this is where some people get confused into using lower temp thermostats. I think it can "band-aid" an overheating problem, in the right circumstances. It's allowing the engine to dip lower than normal, sort of offsetting its inefficient cooling system.

I'm by no means happy with my current set up. One thing I was sure would test it was idling in the drive way at the end of the drive.

I did that, and my temp started climbing until 217F, when I shut it off. I may have had a poor cooling system prior to my initial flush, I just hadn't worked it hard until now, so I never observed a problem.

I checked my fan clutch once it was pretty cool (1 hour after) and it is super stiff. It acts the same at full cold. I can't spin it more than 1/8 of a turn, even forcefully. There is no up/down, in/out play either.

How hot should I expect the rig to get when idiling? Certainly it should level out. Does anyone think the fan clutch is bad?
Attached Files
File Type: pdf trackLog-2017-Sep-13_17-43-20.pdf (274.6 KB, 8 views)

Last edited by Marleyx1981x; 09-14-2017 at 07:53 AM. Reason: Added attachment
Marleyx1981x is offline  
post #15 of 75 Old 09-14-2017, 07:55 AM
JEK3
Web Wheeler
 
JEK3's Avatar
2006 LJ Wrangler 
 
Join Date: Jan 2010
Location: Fredericksburg
Posts: 3,047
When your engine starts getting hotter, can you hear the fan getting louder? The clutch should kick in at some point and start getting faster, sounding more like a jet engine.

FYI, here's what the FSM says about testing the fan clutch:

VISCOUS FAN DRIVE

NOISE
NOTE: It is normal for fan noise to be louder (roaring)
when:
The under hood temperature is above the
engagement point for the viscous drive coupling. This
may occur when ambient (outside air temperature) is
very high.
Engine loads and temperatures are high such as
when towing a trailer.
Cool silicone fluid within the fan drive unit is
being redistributed back to its normal disengaged
(warm) position. This can occur during the first 15
seconds to one minute after engine start-up on a cold
engine.

LEAKS
Viscous fan drive operation is not affected by small
oil stains near the drive bearing. If leakage appears
excessive, replace the fan drive unit.

TESTING
If the fan assembly free-wheels without drag (the
fan blades will revolve more than five turns when
spun by hand), replace the fan drive. This spin test
must be performed when the engine is cool.
For the following test, the cooling system must be
in good condition. It also will ensure against excessively
high coolant temperature.
WARNING: BE SURE THAT THERE IS ADEQUATE
FAN BLADE CLEARANCE BEFORE DRILLING.
(1) Drill a 3.18 mm (1/8 in.) diameter hole in the
top center of the fan shroud.
(2) Obtain a dial thermometer with an 8 inch stem
(or equivalent). It should have a range of -18 - 105C
(-4- 220 F). Insert thermometer through the hole in
the shroud. Be sure that there is adequate clearance
from the fan blades.
(3) Connect a tachometer and an engine ignition
timing light (timing light is to be used as a strobe
light).
(4) Block the air flow through the radiator. Secure
a sheet of plastic in front of the radiator (or air conditioner
condenser). Use tape at the top to secure the
plastic and be sure that the air flow is blocked.
(5) Be sure that the air conditioner (if equipped) is
turned off.
WARNING: USE EXTREME CAUTION WHEN THE
ENGINE IS OPERATING. DO NOT STAND IN A
DIRECT LINE WITH THE FAN. DO NOT PUT YOUR
HANDS NEAR THE PULLEYS, BELTS OR FAN. DO
NOT WEAR LOOSE CLOTHING.
(6) Start the engine and operate at 2400 rpm.
Within ten minutes the air temperature (indicated on
the dial thermometer) should be up to 88 C (190 F).
Fan drive engagement should have started to occur
at between 74 - 85 C (165 - 185 F). Engagement
is distinguishable by a definite increase in fan flow
noise (roaring). The timing light also will indicate an
increase in the speed of the fan.
(7) When the air temperature reaches 88 C (190
F), remove the plastic sheet. Fan drive disengagement
should have started to occur at between 57 -
82 C (135 - 180 F). A definite decrease of fan flow
noise (roaring) should be noticed. If not, replace the
defective viscous fan drive unit.

CAUTION: Engines equipped with serpentine drive
belts have reverse rotating fans and viscous fan
drives. They are marked with the word REVERSE to
designate their usage. Installation of the wrong fan
or viscous fan drive can result in engine overheating.

CAUTION: If the viscous fan drive is replaced
because of mechanical damage, the cooling fan
blades should also be inspected. Inspect for fatigue
cracks, loose blades, or loose rivets that could
have resulted from excessive vibration. Replace fan
blade assembly if any of these conditions are
found. Also inspect water pump bearing and shaft
assembly for any related damage due to a viscous
fan drive malfunction.
JEK3 is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the JeepForum.com forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid e-mail address for yourself.



Email Address:
OR

Log-in









Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome