1998 Jeep Grand Cherokee 5.9 Limited v8 - JeepForum.com
 
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post #1 of 12 Old 06-11-2012, 03:25 PM Thread Starter
mjazzy
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1998 Jeep Grand Cherokee 5.9 Limited v8

Hi,
Sorry I'm new to the forum and I was wondering if anyone can help me. I Have a 1998 Jeep Grand Cherokee 5.9 Limited v8 with around 134,000 miles on it. I've been having an overheating Issue lately and I can't seem to figure out what the problem is. The fan turns on the second I switch the key to start and it stays on while the engine is running which is perfect because it has always been that way. I drive about 15-20 minutes and Tempreature rises slowly until it reaches 225. It's the same problem with or without the A/C being used. I installed brand new Mopar Thermostat, brand new water pump & I also have new oil pump. I pressure tested the radiator and there are no leaks at all. I flushed the radiator & filled it with Antifreeze/Coolant. I checked the head gasket for leak and there is none. Heater works perfect & coolant level is still the same for over a week. I know my car has a two speed electric fan because I had it replaced just last year but I really can't tell if the high speed fan is coming on when it is supposed to. I've checked the relayes on the passenger side inner fender and they both Have "HI RAM" written on them. I switched the relayes to see if the fan turns on and it still works. "Coolant Sensor Bad" message shows on the info center sometimes but I don't know if that has anything to do with the problem.

Any help would be much appreciated! PLEASE!

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post #2 of 12 Old 06-11-2012, 03:55 PM
DeejayZeejay
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Might have air trapped in the system, condensor might not be letting good air flow through the radiator. The sensors could be reading incorrectly. Have a scanner hooked up to read the actual temp. Just a couple things to check.

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post #3 of 12 Old 06-11-2012, 04:39 PM
Texas ZJ1
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I'm making the guess that you've checked for air bubbles in the system by now. With the engine cool, aqueeze the upper hose to see if it is full of coolant or empty.

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post #4 of 12 Old 06-11-2012, 04:46 PM
ratmonkey
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very rarely the parts stores give out the wrong water pumps for these motors. the older 318/360 with v-belts uses a "standard" rotation pump and the serpentine belt equipped vehicles use a reverse rotation pump. the standard pump will not provide adequate flow due to the impeller vanes turning the wrong direction.
if you have eliminated all other possibilities, remove the water pump and see if the impeller is marked with an "R". this problem only really effects the pumps with the bolt on belt pulley, not the pressed on one.

first, i would get a mechanical temp gauge on it to ensure that it really is climbing that high.
the fan should NOT be running constantly, sounds like the relay is stuck in the "latched" position unless the ac is on 100% of the time.
ensure the system is burped, ensure the t-stat is not stuck(failsafe stats suck btw, they're more fail than safe)
make sure the trans isn't overheating and contributing to the heat in the system
make sure the fins of the ac condenser are clean.

'97 zj 5.2, some stuff, some other suff, and some things that even work sometimes.

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post #5 of 12 Old 06-12-2012, 12:29 AM
mrclark25
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it sounds like you know what you're doing, but ill bring it up anyway:

i have heard of similar issues from putting the thermostat in backwards. it should have the coil/spring part down.


about 75% of zj jeeps will have that "coolant sensor bad" message on the VIC... i call it normal

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post #6 of 12 Old 06-12-2012, 12:53 AM
hdrocknroll
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Sounds like U may have a fan problem, but my 2 cents
Easy way to see what temp you are actually running at, is get a hold of a Non-Contact Infrared Thermometer, even a cheap one will do,
good tool to have, and they may be available as a loan a tool.

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post #7 of 12 Old 06-12-2012, 07:51 AM Thread Starter
mjazzy
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Quote:
Originally Posted by DeejayZeejay View Post
Might have air trapped in the system, condensor might not be letting good air flow through the radiator. The sensors could be reading incorrectly. Have a scanner hooked up to read the actual temp. Just a couple things to check.

Hi DeejayZeejay,

Coolant does not bubble or boil. Everything seems fine except for the temp reading. Regarding the condensor. Is there any possible way to check that?

Thanks
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post #8 of 12 Old 06-12-2012, 08:01 AM Thread Starter
mjazzy
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Quote:
Originally Posted by Texas ZJ1 View Post
I'm making the guess that you've checked for air bubbles in the system by now. With the engine cool, aqueeze the upper hose to see if it is full of coolant or empty.Hunter
Hello Hunter,
Yea, I've checked that. I flushed the radiator, drained it properly several times until water started running clean then I filled it with coolant. I checked the coolant in the radiator later that day and added more coolant. I squeezed the upper hose as you suggested and coolant level in the radiator rises once I do it and drops back to normal when I let go....


Thanks again

Jasmine
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post #9 of 12 Old 06-12-2012, 08:15 AM Thread Starter
mjazzy
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Quote:
Originally Posted by ratmonkey View Post
very rarely the parts stores give out the wrong water pumps for these motors. the older 318/360 with v-belts uses a "standard" rotation pump and the serpentine belt equipped vehicles use a reverse rotation pump. the standard pump will not provide adequate flow due to the impeller vanes turning the wrong direction.
if you have eliminated all other possibilities, remove the water pump and see if the impeller is marked with an "R". this problem only really effects the pumps with the bolt on belt pulley, not the pressed on one.

first, i would get a mechanical temp gauge on it to ensure that it really is climbing that high.
the fan should NOT be running constantly, sounds like the relay is stuck in the "latched" position unless the ac is on 100% of the time.
ensure the system is burped, ensure the t-stat is not stuck(failsafe stats suck btw, they're more fail than safe)
make sure the trans isn't overheating and contributing to the heat in the system
make sure the fins of the ac condenser are clean.
Hi,

You are totally right about the water pump but I believe this is not the Issue I am having because the one I have installed is mopar original, my dad got it like a year ago but never installed because the one I had on was still good. I didn't replace till like few weeks when it started leaking from the front bottom. temp and all that seemed fine till now.

I guess my next step would be getting a mechanical temp gauge to see what the actual temp is!!

Thank you for your time!
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post #10 of 12 Old 06-12-2012, 08:26 AM Thread Starter
mjazzy
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Quote:
Originally Posted by mrclark25 View Post
it sounds like you know what you're doing, but ill bring it up anyway:

i have heard of similar issues from putting the thermostat in backwards. it should have the coil/spring part down.


about 75% of zj jeeps will have that "coolant sensor bad" message on the VIC... i call it normal

Hahaha you almost got me there. I started thinking that I put it the wrong way so I went and checked that right away after I read your message. You put me on a mission removing the upper hose from the thermostat housing to be able to get to the thermostat again..It is a pain in the butt in ZJ 5.9....
Thanks for bringing that up though...now I am a 100% positive that I did it right!

Jasmine
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post #11 of 12 Old 06-12-2012, 08:43 AM Thread Starter
mjazzy
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Quote:
Originally Posted by hdrocknroll View Post
Sounds like U may have a fan problem, but my 2 cents
Easy way to see what temp you are actually running at, is get a hold of a Non-Contact Infrared Thermometer, even a cheap one will do,
good tool to have, and they may be available as a loan a tool.
Hmmmm I was told before that maybe my High speed fan is not coming on. I am thinking about removing the fan assembly to the check if the motor high speed brushes are worn out or not and maybe clean them as well..

Does the Non Contact Infrared Thermometer give the exact temp reading? We are getting burned by the heat & sun down here in Miami you know.

Thank you for your time!
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post #12 of 12 Old 06-12-2012, 08:54 AM
PolkaPower
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You should be able to hear the high speed kick on from the fan. I can clearly hear it in mine. Get the motor up to operating temp then turn the ac on full blast. If the fan speed doesn't change then there is your answer. You can just do this in your driveway with the hood up.
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