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Discussion Starter · #1 ·
I have a 84 Jeep with a I-6. Everything is stock. I receintly had a leak in the radiator and replaced the radiator. Now my temperature keeps fluctuating. Some times it will be really hot other times it will in the middle. I assume the next step would be to check the water pump and the thermostat. How do I check the water pump? Can I just start the vehicle and open the cap and see if the water is moving? How do I check the thermostat?

Also I am new to this. I assume the water pump is always running? Not that it comes on and off when ever the thermostat reaches a certain temperature? If this is the case is the thermostat just a measuring device so you can see the temperature in the cab?

Thanks for any and all help.

 
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Discussion Starter · #2 ·
I assume NO heating problems before radiator replace? was it a stock replacement? same number of cores,etc?was it new or a junk
yard radiator? could be partly plugged if it wasnt new or reworked by a rad shop.
A water pump if belt driven runs all the time,as yours should since you said it was all stock.Most water pumps never quit pumping,they
usually start leaking,and bearings/bushings in them go out.See any leaks below pump? wiggle fan baldes and see if there is any movement
in pump pully indicating worn bearing/bushings.
The thermostat is a device that is closed when cold to aid in fast warm up of motor,and opens at a set temp to allow cooling,it adjusts
flow thru its opening to maintain a constant temp,as close to setting as possible anyway.They dont last long sometimes.I have had
new ones fail in less than a year.I would try replacing that first.It should be stamped on the bottom or flange what temp it is,ie:160 180
190 195 etc.I run a 180 with no problems in a stock 258 with a new radiator.
Another thing to check is the fan clutch if it has one,its the type that you can turn fan blades with engine shut off.if they go out of whack
it could heat up.Fixing this is limited to a new clutch replacement.And since you just replaced the radiator,i assume you have a shroud
on it? and didnt leave it off? they need that plastic shrould to channel air flow thru radiator.REMEMBER ! never open a hot radiator cap!
and one more thing,are you sure cooling system is all the way full? have a catch tank on it? can get same symtoms if engine isnt
full with no air it it.But first,check for water pump loosness,that costs 0.00 then go buy a new 5.00 thermostat,and refill with a 50/50
mix of antifreeze and water, no more than a 70/30 anitfreeze to water mix.They need the water content to transfer heat.never run pure
antifreeze.Oh,make sure fan belt is in good shape,not cracked.glazed/or loose.
have a 84 Jeep with a I-6. Everything is stock. I receintly had a leak in the radiator and replaced the radiator. Now my temperature
keeps fluctuating. Some times it will be really hot other times it will in the middle. I assume the next step would be to check the
water pump and the thermostat. How do I check the water pump? Can I just start the vehicle and open the cap and see if the water
is moving? How do I check the thermostat?

Also I am new to this. I assume the water pump is always running? Not that it comes on and off when ever the thermostat reaches a
certain temperature? If this is the case is the thermostat just a measuring device so you can see the temperature in the cab?

Thanks for any and all help.


 
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Discussion Starter · #3 ·
One thing LoneEagle didn't mention which is THE most overlooked cooling system problem is the water pump impeller coming loose
from the shaft inside the pump. Don't forget to check it out.

Brad (from the 4 Wheeling center of the universe, 4 corners USA)
 
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Discussion Starter · #4 ·
It is a new radiator. I got it form Advance. I assume it is the same type of radiator.

It did not have a fan shroud on it. Should I get one and put it on it?

Never open radiator cap when hot? I always assumed this was because steam or boiling water might shoot out and hurt you but will this hurt your engine?

I think I will try replacing the thermostat.

Thanks

 
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Discussion Starter · #5 ·
Also make sure that your radiator cap is in good working order. If it is old then go the parts store and just get a new 16lb or 17lb cap with a pressure lever on the top. If you cooling system isn't sealed good this can also cause a cooling problem.

 
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Discussion Starter · #6 ·
Your problem is most likely that you don't have a fan shroud. I swapped engines in my 89 Wrangler and I didn't have a fan shroud and it caused overheating problems.....as soon as I put a shroud on...waah laah no more overheating problems.

absolutjeep
 
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Discussion Starter · #7 ·
Thanks for the suggestion but I think I will try the other things before the fan shroud. You mentioned that you swapped engines so maybe you were getting more output. I did not change anything except the radiator.


 

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6,517 Posts
Does it seem to only overheat when the engine is idling or nearly idling, and the Jeep either moving slowly or not moving???

Tim
"The_Sandman_454"

/wwwthreads_images/icons/cool.gif '79 Suburban 4x4 454, 6" lift, 35x12.5s & '85 GMC S15 4x4
 
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Discussion Starter · #9 ·
If you are new to this type of work, be careful when you replace the thermostat that you don't put it in backwards. It would fit either direction, but they only work one way. Don't pinch pennies on the thermostat, buy the best quality, you can. John

 
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Discussion Starter · #10 ·
I had a 95 Mustang GT that I bought new in late 95. I took a little road trip, to clear my head and enjoy my new Stang. It was my dream car, loved it. As I was driving along, I noticed the temp guage was all over the place. I figured that it was the senser, it had been doing for the last 100 miles. I stopped to get me a double Whopper with cheese, and I was on my merry way again. Soon after getting on the Interstate, I noticed the temp gauge was pegged, I couldn't smell anything, so a finished my Whopper. I exited at the first exit after finishing my supper. I pulled the the side of the road, popped the hood, antifreeze was spraying out of everywhere. Hated the car after that.

80 CJ7 with 4 inch lift, 33x12.50x15 Trail T/A
98 KX250
 

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3,478 Posts
The fan shroud is a VERY important item. It allows the fan to develop suction pressure to draw air thru the radiator. If the shroud is missing the air simply "slips" around the blades and there isn't enough air movement thru the radiator. Make sure that the edge of the fan blades is half way inside the shroud.

If you have a clutch fan, you can check it by trying to spin it by hand with the engine off. It should be very hard to spin it by hand. If the fan spins freely, then the clutch is bad and must be replaced. Good Luck!! /wwwthreads_images/icons/smile.gif
 
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Discussion Starter · #13 ·
Put the stupid shroud on it. Make sure there is enough coolant. Turn heater on and drive it up the steepest hill you can find to try and get any air bubbles out of the system. But the shroud alone will probably do it.


Mark
 
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Discussion Starter · #14 ·
Well, I took it for a spin the other day. While I was on the interstate going up and down hills, it stayed at a constant cool temperature. When I was idling or was driving slow the temperature started to increase.


 
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Discussion Starter · #15 ·
Idleing and driving slow are the conditions where the fan shroud will help the most. You need airflow for heat transfer. At higher speeds air is forced through the radiator and cools it down. If it stayed hot at higher speeds, you would have a thermostat or water pump problem. Sounds like either a lack of a shroud, a bad fan clutch (if applicable), or clogged tubes in the radiator. If you don't know what these things are or how to check them, find somebody who does or get a service manual and learn how to check them. Don't just take a shot in the dark until you find the culprit. It's a waste of time and money!

 
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Discussion Starter · #16 ·
With my 83' CJ7 I-6 258 no A/C, I never had any overheating trouble while I was driving it, even during the summer. I did not have a
shroud, but I did have a three core radiator, and no fan clutch. Every jeep is different though, and a fan shroud will surely help if you
can find one.
good luck,
Ethan

 

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Official Curmudgeon
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4,707 Posts
When I re-read your question, I realized this was based on the gauge. Have you checked the ground to
the gauge. With no ground the gauge will go to full hot, with intermittent or poor ground, it will fluctuate
just like you described.. Take it from somebody with a fiberglass body tub, I know.


 
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