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Why is it still OVERHEATING?

C

Cherokeelaredo

NAXJA Forum User
Location
Aurora, Canada
Here is the story:
When I got the truck ,I didn't know/realize that it was running hot. Well long story short, used rad, new head gasket, new head, new T stat, coolant bottle/cap, later, its still overheating!!! What the hell could it be? It overheats only when wheeling, when I drive it in the city it runs a tad cool if anything, it never passes the half mark. When wheeling, it overheats pretty quickly, and we are talking in +3 to 4 Celsius. My truck, didn't come with the A/C so there is no Electric fan, something I am planning on putting ASAP, but should that be the culprit? What else could it be, and should I check?
It is a 1989 Laredo 4.0 Auto NP 242.
 
You did not mention too of the most important things, fan clutch and waterpump. Are you sure that they are both in working order?

K
 
Sarge: Depends on how hard I push it. Sometimes it boils over, others not.

Kataran44: If the water pump is not good, wouldn't the car be overheating all the time? At least that was my dads experience with his volvo.
As far as the clutch fan goes, how would i find out?
 
Well..when you are moving on the highway...even if off and on at speed...you do get some more air cooling. another thing to check...is your belt condition. mine was just alittle loose, and before i knew it it was glazed and not spinning the water pump properly. new belt and proper tension fixed all my problems. i was getting ready to change water pumps and radiators and etc etc... give the belt a once over if you havent. might save ya some headaches.
 
Cherokeelaredo said:
Here is the story:
..........used rad.....It is a 1989 Laredo 4.0 Auto NP 242.
Click to expand...

Mmmm. If it's a 17-year-old rad, I'd say it's well past its best and needs replacing. Might be a good time to convert to the '91+ open style cooling system. It'll get rid of that stupid pressure bottle for starters.
 
Ok, I was out for the past 30 minutes or so, and re tightened all hose clamps, double checked for leaks, and was testing my fan clutch.
My friend called me and told me that to test my fan clutch I can use a newspaper to see if it'll stop.
What I did was, start it up, let it run for some time, then insert newspaper(carefully!) into fan. If I only insert the tip of the paper, the fan slows down VERY little, but shreds it, if I fully insert the paper(about half, it stops completely. According to him that may be my problem. He also suggested to let the car warm up, shut it off, and see if I can spin the fan. I can push it easily, bit if i try to spin it, at most it will spin one blade from where I spin it.
Any ideas?
 
first let me say...sticking things into the fan is NOT a good test procedure. now that thats out of the way...
the fan clutch sounds like its acting normal... it should be easy to "push"...but should resist "spinning" with the engine off. someone else can chime in with the inner workings...but i think its similiar to the torqure converter inside??? but uses a coil to detect heat and to engage the fan...

I dont know..point is, it doesnt sound like its doing anything odd...

also...do all XJs without A/C come without an aux. elec. fan? I thought I saw an XJ without A/C from the factory and it still had the elec fan on the right...

did you check out the condition of the belt for tension and for glazing??
 
I went through this whoile rigamorole a whole back.
It would run REAL hot...190-210

I changed the fan clutch, flushed the system, new thermostat, hoses, temp gauge, etc.

Never fixed it. I was about to buy a new rad and replace the whole systen again....

Finally I backed the ass end up a hill and unscrewed the temp sensor at the rear drivers side of the block and "burped" the system.

Problem solved.
 
ghettocruiser said:
first let me say...sticking things into the fan is NOT a good test procedure. now that thats out of the way...
the fan clutch sounds like its acting normal... it should be easy to "push"...but should resist "spinning" with the engine off. someone else can chime in with the inner workings...but i think its similiar to the torqure converter inside??? but uses a coil to detect heat and to engage the fan...

I dont know..point is, it doesnt sound like its doing anything odd...

also...do all XJs without A/C come without an aux. elec. fan? I thought I saw an XJ without A/C from the factory and it still had the elec fan on the right...

did you check out the condition of the belt for tension and for glazing??
Click to expand...
Fan clutch uses a temperature sensitive viscous clutch. As temp heats up the fluid get's "stiffer" and the fan is more like direct drive.
I think that the aux fan depends on a few things. My 87 MJ with no AC doesn't have it, but I saw another MJ in the JY that had the tow/metric tonne package that had it but no AC. Of course mine's a 5 spd and that was an AW4, so maybe they put it on there for the tranny cooler also.
 
If you doubt the fan clutch , replace it- there is no 100% way of testing it. THe second thing is i really think all xjs came with electric fans regardless of AC or not, i would check on that. Secondly never buy a used radiator, who know whats its condition ?

Check your pressure bottle/cap isnt leaking and is keeping pressure.

pete
 
A good fan clutch will cause the fan to make a good bit of noise like roar when the engine is started cold. Also the closed cooling system does need burped. What happens is air gets trapped in the thermostat area and the thermostat never opens because there's no hot water around it. You can get a thermostat housing from a 91 or newer model and put in a drain valve in the hole. Then open it slightly and let the air out being carefull to not get burned.

Good luck
JoBo
 
Biernuts said:
Finally I backed the ass end up a hill and unscrewed the temp sensor at the rear drivers side of the block and "burped" the system.

Problem solved.
Click to expand...
I should definitely try that.
I am also going to look for this screw on the t-stat housing, because my head is from a 94 Ho.
 
Cherokeelaredo said:
I should definitely try that.
I am also going to look for this screw on the t-stat housing, because my head is from a 94 Ho.
Click to expand...
You should still have the electric fan, if you notice your engine fan only covers half the radiator. The AUX fan is required A/C or no A/C.
 
Should be an electric fan with a 4.0 in 89, with or without A/C, according to my schematic. Slight difference in part of a wiring harness, but nothing big. You should have a temperature sensor screwed into the radiator in the rear driver's side, and a relay on the top of the driver's front fender near the edge where the hood closes, that turns it on and off. This can be manipulated to add a switch for manual operation or to keep the fan running after shutting down for guys like me who used to live in a hot climate.

When my electric fan needed replacement, I had the same symptoms of overheating. As far as the engine goes, I personally can live with 210°; that's about 15° above the correct thermostat. I can even live with 220°. The boiling point of water is 212°F. Factor in that the system is under pressure and there is a mixture of ethylene glycol or a similar anti-freeze will further raise the boiling point of the coolant to over 260° given a 50/50 mix and 15 PSI.

If it were me, I would replace the fan clutch due to age and find an electric fan. Assuming, of course, there isn't any mechanical issues that might be the cause of the overheating.
 
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