[TINTINUAE]

Ok, so yesterday I removed the thermostat on my 98 5.2 zj as I live in the middle east and have no issues with the engine getting warm, the average air temp in the summer is 48 degrees C, winter is 20 degrees C. So a good friend of mine who is on this forum with a 92 XJ told me that without the thermostat it will take a little longer to warm up but should run a few degrees lower than normal.
The problem is, at first it seemed to do exactly that, then on my way to work this morning it went above 100 deg C (middle of the gauge) which this time of year it should reach max 90c. Could this be because I haven't reset the system after removing the t-stat or is it just a bad idea alltogether. I flushed the rad and block with clean water and re-filled the rad with clean water, we don't need anti-freeze here as it never gets cold.
Also I cleaned the throttle body and replaced the MAP sensor the other day as it was having cranking problems, it would crank solid for about 5 seconds then fire up, if I turn the key on-off 4-5 times it will start like new, after cleaning the t-bod it started like new the first few time then the next day back to normal old crappy cranking.
I've also changed the plugs, wires, new filter again, new fuel pump, changed out some fuses to be sure and had a major servce and new battery, I cant figure this one out now.

Cheers guys in advance.

Tony.

[SET2JET]

did you have antifreeze in there before removing the t-stat? antifreeze helps dissipate heat

[TINTINUAE]

Not as far as I know, just water in the rad and coolant in the resavouire.

[SET2JET]

not really sure but i think with out the t-stat the coolant moves to fast so it doesn't stay in radiator long enough to cool down that much

[TINTINUAE]

So I guess I should replace the t-stat to be sure of this?

[TINTINUAE]

Do you think if I drained the rad again and used a mix of say 60% coolant and 40% water it would be better? Sorry if this is newbie crap but thats me mate.

[Mickey_D]

I have tried what you did a few times until someone explained to me why it's a bad idea.

Antifreeze helps transfer heat back and forth to the water. From the engine and to the air. I'm not versed in the chemistry of it, but I have done trials and tests and found it to be true.

Also as SET2JET said, the thermostat creates restriction to the water flow through the radiator, giving it time to process the heat out into the air. If you get the water moving too fast (which it will without the thermostat in there) it won't hang out in the radiator long enough to do any good.

Things to do that will help A LOT:

Find a de-scaling flush to run through. Scale makes for a great insulator in a cooling system. If there's any in there, you want it out. Don't trust these things from Prestone and the like that you buy at parts stores. They don't work too well. I haven't tried it myself, but I've been told CLR works fantastic. Again, I can't endorse that one myself as I've never tried it.

Believe it or not, new hoses can make a hell of a difference. Why? I have no idea, but I have seen it myself.

A good antifreeze works wonders. Especially if you can get the (believe it or not) Extra Cold Duty stuff. The one that's good to 50 below or something (regular is good to 40 below). ONLY run antifreeze at 50/50 mix. Any more or less decreases its performance. This is why it's good to premix it before you pour it in.

A lower temp thermostat will help, just don't get one of the "high performance" ones. They are designed for race engines that are only run for brief periods of time and lessen the restriction on the water pump, giving a minuscule amount of extra horsepower due to lesser drag. But they will actually hinder what you're trying to do. Stant are a good brand.

Now, if you're STILL having overheating issues, there's a little trick that works quite well out where you're at due to the very low humidity:
Get an extra windshield washer reservoir and pump. Run the tube up to in front of the radiator but behind the grill. Find some way to mount the washer sprayer nozzle so it's pointing at the radiator. Wire the pump into a momentary contact switch close by on the dash. When you notice it starting to heat up a lot, give the button a couple second push to wet down the radiator. The evaporating water will take away an IMMENSE amount of heat VERY quickly to the point that you should see your temp gauge move within seconds. And it will move A LOT. You don't want to do more than a few seconds with this as you'll start spraying water all the way through the radiator and it will start hitting the engine. Too much too quickly and something could crack from thermal shock. But the gradual cooling the radiator will do with this system negates that problem so long as you don't douse it in too much water. It's kind of redneck, but trust me it works. Take a look at the HVAC systems on buildings - they use this exact system on a grand scale on their A/C units.

[TINTINUAE]

Originally Posted by Mickey_D

I have tried what you did a few times until someone explained to me why it's a bad idea.

Antifreeze helps transfer heat back and forth to the water. From the engine and to the air. I'm not versed in the chemistry of it, but I have done trials and tests and found it to be true.
Anti freeze is pretty much impossible to get hold of here as the temp never even gets close to zero, will look out for some though

Also as SET2JET said, the thermostat creates restriction to the water flow through the radiator, giving it time to process the heat out into the air. If you get the water moving too fast (which it will without the thermostat in there) it won't hang out in the radiator long enough to do any good.
that makes good bloody sense really, may just replace the t-stat
Things to do that will help A LOT:

Find a de-scaling flush to run through. Scale makes for a great insulator in a cooling system. If there's any in there, you want it out. Don't trust these things from Prestone and the like that you buy at parts stores. They don't work too well. I haven't tried it myself, but I've been told CLR works fantastic. Again, I can't endorse that one myself as I've never tried it.
again, makes sense, I'm going to ACE hardware today so will take a look

Believe it or not, new hoses can make a hell of a difference. Why? I have no idea, but I have seen it myself.
I replaced the hoses about a month ago so thats not the issue I hope

A good antifreeze works wonders. Especially if you can get the (believe it or not) Extra Cold Duty stuff. The one that's good to 50 below or something (regular is good to 40 below). ONLY run antifreeze at 50/50 mix. Any more or less decreases its performance. This is why it's good to premix it before you pour it in.

A lower temp thermostat will help, just don't get one of the "high performance" ones. They are designed for race engines that are only run for brief periods of time and lessen the restriction on the water pump, giving a minuscule amount of extra horsepower due to lesser drag. But they will actually hinder what you're trying to do. Stant are a good brand.
I may look into this but I've been told that for the money they cost compared to the heat reduction its just not worth it

Now, if you're STILL having overheating issues, there's a little trick that works quite well out where you're at due to the very low humidity:
Get an extra windshield washer reservoir and pump. Run the tube up to in front of the radiator but behind the grill. Find some way to mount the washer sprayer nozzle so it's pointing at the radiator. Wire the pump into a momentary contact switch close by on the dash. When you notice it starting to heat up a lot, give the button a couple second push to wet down the radiator. The evaporating water will take away an IMMENSE amount of heat VERY quickly to the point that you should see your temp gauge move within seconds. And it will move A LOT. You don't want to do more than a few seconds with this as you'll start spraying water all the way through the radiator and it will start hitting the engine. Too much too quickly and something could crack from thermal shock. But the gradual cooling the radiator will do with this system negates that problem so long as you don't douse it in too much water. It's kind of redneck, but trust me it works. Take a look at the HVAC systems on buildings - they use this exact system on a grand scale on their A/C units.

that is redneck, I like it, the thing is we have a lot of humidity out here, sometimes reaching 90-100% in the summer plus with the heat generated from the engine+outside air temp I don't think it would make much difference as I do a lot of dune bashing in it which would cause it to clog the rad fins with sand I guess. Sometimes I'm driving for 6 hours minimum in 120+ degF , in very very soft sand

Really appreciate the info and may just replace the old t-stat as it works fine, I will try the de-scaler and antifreeze first though.

Thanks pal.

[Mickey_D]

Try checking with plumbers. Any form of ethylene glycol is a good antifreeze. Also see if you can get in friendly with anyone on a military base. They are required by milspec to have antifreeze in their vehicles at all times. Maybe one of them could get a hold of some for you.

And yes, you are correct. A cold water sprayer system would be fatal to your Jeep in the sand.

[TINTINUAE]

Well it turns out it was the fan, for some reason uknown to man it wouldn't run at all, now me and a friend played around with some stuff at lunch time and we couldn't for the life of us get the fan to work, so I thought, I'll go to the scrappy and get a second hand one.
Well I got to the closest gas station possible as the gauge was 3/4 the way to the end so I had to stop.
I let it rest for a while with the battery disconnected to reset the whole system and though, while I'm here I'll empty the coolant box and clean it out.
The bloody thing was filthy with all sorts of crap in there, I forgot to clean it out when I flushed the rad and block. Well the rad is fine, the fan is spinning like new and the temp is lower than average which is a good thing.
I used some ethylene glycol based coolant and now it seems great so lets wait and see. I will get back to you if there is anymore problems.

Cheers

[YJMCBoy]

Originally Posted by SET2JET

did you have antifreeze in there before removing the t-stat? antifreeze helps dissipate heat

?? I don't know where you heard this but anti freeze has a significantly worse heat transfer than pure water. Engineering toolbox is a great reference:
http://www.engineeringtoolbox.com/et...col-d_146.html

Look at the table for specific heat of ethylene glycol then read the paragraph right below it.

[TINTINUAE]

Ok, so I'm getting confused now. I just want to recap on my situation.

I live in one of the hottest countries in the world so anti-freeze solutions are not needed. EVER!!! never below15 degrees C EVER!!!
My t-stat removed makes the engine run cooler, bonus.
My fan is playing up, bummer. (need to change this week)
When I fill the rad, should I use just water or water and coolant 50/50 mix? and if mixed should I do the same for the coolant box?
Will I be fine just using water through the whole system?

Thanks for all the info guys. Appreciated

[TINTINUAE]

I'm thinking of ordering a 160 degree t-stat for my rig now but need to know something.
I was looking through quadratec's site and saw the Robertshaw t-stat for the 93-95 4.0L ZJ and followed the link onto the product page, which says it is only for the below models.

72-83 Jeep CJ-5
72-75 Jeep CJ-6
76-86 Jeep CJ-7
81-85 Jeep CJ-8
97-02 Jeep Wrangler (TJ)
87-95 Jeep Wrangler (YJ)

So no sign of any ZJ models in this list so will this fit my 98 5.2 or is this not possible.

This is the list page link http://www.quadratec.com/advisor/jee...thermostat.php

This is the product page link http://www.quadratec.com/products/51211_52.htm

Thanks again guys.

[YJMCBoy]

Originally Posted by TINTINUAE

Ok, so I'm getting confused now. I just want to recap on my situation.

I live in one of the hottest countries in the world so anti-freeze solutions are not needed. EVER!!! never below15 degrees C EVER!!!
My t-stat removed makes the engine run cooler, bonus.
My fan is playing up, bummer. (need to change this week)
When I fill the rad, should I use just water or water and coolant 50/50 mix? and if mixed should I do the same for the coolant box?
Will I be fine just using water through the whole system?

Thanks for all the info guys. Appreciated

If you add antifreeze you will be removing less heat from your engine.

If you have straight water more heat will be recovered from the block and subsequently (and theoretically) dissipated through your radiator. If you use water, use distilled or purified water as standard "tap" or hose water has plenty of minerals that will deposit and gunk up your coolant passages over time.

bottom line.

[TINTINUAE]

Originally Posted by YJMCBoy

If you add antifreeze you will be removing less heat from your engine.

If you have straight water more heat will be recovered from the block and subsequently (and theoretically) dissipated through your radiator. If you use water, use distilled or purified water as standard "tap" or hose water has plenty of minerals that will deposit and gunk up your coolant passages over time.

bottom line.

SO IT WOULD BENFIT ME TO REMOVE THE GLYCOL COOLANT FROM THE COOLANT TUB AND USE DISTILLED WATER ALL THE WAY THROUGH THE SYSTEM? MAKES SENSE REALLY.