Overheating Issues (1 Viewer)

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Jul 20, 2021
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Location
Phoenix, AZ
I have an '87 Fj60 with some overheating issues. I live in Phoenix, which is basically the surface of the sun during the summer months. That being said, the last few times I have taken her out, she started to overheat. The thermostat does not drop below 3/4 of the gauge wile driving, and continues to creep up into the red at red lights. I replaced the radiator and thermostat just 2 years ago hoping that would help with some of the issues, but to no avail.

My next plan of attack is to install an aluminum radiator, remove the thermostat, and replace the water pump with a high-flow pump. I read that I have to ground the radiator because of electrolysis. Is this true? As far as removing the thermostat, has anyone done this? Does anyone have any ideas? I would appreciate the help.

Thanks,
Ben
 
Removing the thermostat will cause the engine to run hotter when the cooling system is maxed out.

The thermostat housing has a bypass circuit that recirculates the coolant back to the water pump without passing it through the radiator. It's there to facilitate rapid warm up and to keep the temperature stable once the thermostat opens.

The thermostat has what amounts to two water passages. The main passage in the center that feeds to the radiator and the passages along its outer shell that feeds the bypass circuit.

When the thermostat is closed on a cold engine, the coolant flows through the bypass holes in the shell back to the water pump. As the thermostat begins to open when the coolant heats up, the bypass passageway gets smaller as the main passageway gets bigger- until the main passageway is open completely and the bypass passages are completely shut off.

When the thermostat is removed, hot coolant will always flow through the bypass circuit - sidestepping the radiator, so a good proportion of the hot circulating coolant just gets recirculated over and over again without going through the radiator.

Bottom line: removing the thermostat will decrease the efficiency of a hot engine cooling system and will make it run even HOTTER.

It's deceptive though because when the engine cooling system isn't being taxed, the system will run cooler (too cool) without a thermostat. But once everything gets hot (especially in AZ in the summer) removing the t-stat will just make the overheating situation worse.
 
make sure your fan clutch is working properly

*note usually if the clutch is working properly it will roar on cold startup for a minute or 2 and then quieten.
X2 on the fan clutch, as you didn't mention it's been replaced. I have replaced two in 20,000 miles. They just don't seem to last. Next step will be an 80 series clutch. It's supposed to be an upgrade.
 
The stock temp gages are notoriously inaccurate. The advice for everyone with an overheating issue is verify the temp with either a calibrated aftermarket gage or one of those external laser type of gages before you get too worried. Unless you’ve got coolant boiling out.

second piece of advice is put a new OEM radiator cap in

Do not remove the thermostat. The cooling system needs the open/close cycling of the thermostat in order to remove heat properly from the system. If you remove the thermostat the coolant won’t spend enough time in the radiator to exhaust its heat to the air passing through. If you add a high flow pump to this equation you will make it even worse.
 
make sure your fan clutch is working properly

*note usually if the clutch is working properly it will roar on cold startup for a minute or 2 and then quieten.

X2 on the fan clutch, as you didn't mention it's been replaced. I have replaced two in 20,000 miles. They just don't seem to last. Next step will be an 80 series clutch. It's supposed to be an upgrade.

X3. Nothing seems to have improved the efficiency of my cooling system more than a properly installed and working fan clutch. HTH.
 
Something you might consider once all your cooling components are up to par is adding another water tank and water sprayers to spray the front of your radiator. I’m not sure if there are any off the shelf systems but gabbing something wouldn’t be too difficult. Could use a thermo switch in the upper rad hose for the trigger. This would give you the added evaporative cooling effect and improve your cooling when you need it most.
 
Another incremental improvement can be had by replacing your stock 190 degree thermostat with a 180 degree version. But all the components work together as a system, so check the fan clutch as well. And get a real water temperature gauge. My stock one is at just over a 1/4 with 190 degree temps on the real gauge. I saw the stock gauge up to 3/4 regularly until I cooked the head gasket. After getting the pinhole leaks in the radiator fixed , a new fan clutch, radiator cap, lower temp thermostat, a burp kit for filling and getting rid of air in the system, I have never seen temps over 195 in desert conditions very much like you describe.
Good luck
 
I have an '87 Fj60 with some overheating issues. I live in Phoenix, which is basically the surface of the sun during the summer months. That being said, the last few times I have taken her out, she started to overheat. The thermostat does not drop below 3/4 of the gauge wile driving, and continues to creep up into the red at red lights. I replaced the radiator and thermostat just 2 years ago hoping that would help with some of the issues, but to no avail.

My next plan of attack is to install an aluminum radiator, remove the thermostat, and replace the water pump with a high-flow pump. I read that I have to ground the radiator because of electrolysis. Is this true? As far as removing the thermostat, has anyone done this? Does anyone have any ideas? I would appreciate the help.

Thanks,
Ben


installing a aftermarket ALUMINUM radiator will be the biggest mistake you can ever make !

do not do it ............

if you need the whole DOCTRINE on why , simply say so and i will post the facts ...............


use ONLY a SOLID RED brass OEM Toyota one unit

or

a CSF brand all brass aftermarket unit


the aluminum land cruiser 2F and 3FE Radiator offerings are SCAM and fundamentally a wrong parts application bottom line



GHETTO TRASH at the least .......





f70e2761e28cc9805f5306ccfe3cf2d7 - Copy.png
 
Intuitively, the cooler thermostat sounds like a good idea, but doesn't help with overheating.
I agree. While a lower temp thermostat will not solve overheating by itself, in a properly functioning cooling system, it can lower the base operating temperature by opening sooner and staying open longer- If the system has the capacity to take advantage of it. I know in my 60 that was the case.
Once I had everything else sorted out, my average temp dropped 5 to 7 degrees after installing the 180 thermostat vs the 190, with no other changes.
 
Thank you all for the replies! I will not be removing the thermostat! I am going to order a 180 and external gauge, as well as flush the system. As far as radiators go, my current one has sprung a leak since my last post. Should I replace with another brass one, have the current one redone, or go with the aluminum one from cruiser corps? What are the issues with aluminum radiators? I appreciate all of your help!
 
Thank you all for the replies! I will not be removing the thermostat! I am going to order a 180 and external gauge, as well as flush the system. As far as radiators go, my current one has sprung a leak since my last post. Should I replace with another brass one, have the current one redone, or go with the aluminum one from cruiser corps? What are the issues with aluminum radiators? I appreciate all of your help!
The fan clutch also works properly!
 
If your old rad has a core depth [thickness] under 65mm , Like 50mm for example, I would upgrade to a thicker one. Brass vs aluminium? Not sure how much difference to cooling it makes. I just looked at a newish 60 rad in my shed and it's core depth is 65mm, and It has 50 channels. I have seen them with 60 channels, and that would probably be even better.
 
I am in south Texas as hot as the surface of the sun except with more humidity. Also a 1987 FJ60. I am running a CFS radiator. 4 row brass/copper OEM style radiator (drops right in with no modification). 15 years with it no problems. I recently replaced all hoses and thermostat with Toyota parts from the dealership. Highly recommend that. City Racer LLC website shows it as sold out but you can check that out for more info. I know other vendors sell it. If you do get the CFS radiator you will need to buy a cap. I just replaced my torn up one with a cheap one from auto zone duralast 7513 for $9.
 
+1 to the above post. The CSF rad is a good choice. 4 row, and has 60 channels.

Also, if your old radiator has the same dimensions as the CSF rad, you might as well get it fixed, being only 2 years old.
 
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