Another Hot Running FJ Thread (1 Viewer)

[sp73]

My '87 FJ60 is new to me... I've had it three weeks now. Temperature gauge would sit about 7/8 up the white arc but IR gun temps on the upper radiator hose and the radiator itself were 190-ish max. The coolant was low and I decided to drain and refill with NAPA Green (period correct) concentrate and distilled water, 50% ratio.

The engine is running hotter now. 190-205 across the top of the radiator, 190 on the upper radiator hose, and 210 at the top of the thermostat housing. The block, when measured around each spark plug, is 210-218. The temp sensor housing is at 235. It takes about 15 minutes of engine running and driving for those temps to be reached.

The truck has been run at various speeds for at lease one hour; it initially started to overheat but after additional burping/filling it is still hot but not overheating. I am parking it on an incline with the radiator cap as the highest point in the system, and running the engine with the front and heat on full blast. That air is hot!! I even burped from the sensor probe hole at one point. I cannot get the temps any better. New fan clutch, new thermostat, new radiator cap will be installed as soon as it gets here.

Ignoring the dash gauge - which is running at the top of the white and bottom of the red - my temps are 20-30 degrees higher than before the drain and refill. The radiator looks good, I have no idea of the history of that or the water pump at 173K but it seems coincidental that the problem started after I serviced the system. Thoughts appreciated!

 

[OSS]

Every time the coolant is drained, the engine will show hotter on the temp gauge for days afterwards. (My experience is 2 weeks approximately).
The culprit is air bubbles trapped in the cylinder head.
Eventually they work themselves out / always.

The thermostat is rated at 190°. That’s the temperature it starts to open at. Your measured temperature of the radiator inlet hose and top of radiator fall right in line with “fine”.

The oem temperature gauge on the 2F engine is notoriously unreliable. Install an aftermarket gauge if you want to see accurate temperatures.

Also the newly installed thermostat is working properly (if it’s a genuine Toyota thermostat) while the old one that got replaced probably wasn’t.

 

[sp73]

Every time the coolant is drained, the engine will show hotter on the temp gauge for days afterwards. (My experience is 2 weeks approximately).
The culprit is air bubbles trapped in the cylinder head.
Eventually they work themselves out / always.

The thermostat is rated at 190°. That’s the temperature it starts to open at. Your measured temperature of the radiator inlet hose and top of radiator fall right in line with “fine”.

The oem temperature gauge on the 2F engine is notoriously unreliable. Install an aftermarket gauge if you want to see accurate temperatures.

Also the newly installed thermostat is working properly (if it’s a genuine Toyota thermostat) while the old one that got replaced probably wasn’t.

I appreciate your reply, and I understand... but this does not resolve the hotter than previously measured temps around the engine or the whisps of steam I'm seeing after shutdown on one short drive. Maybe I needed to be more clear - I am only using the dash gauge to see if the temp is rising or falling and my IR gun for better measurements. It's good to know it could take longer for the system to settle out.

 

[Old Nick]

My '87 FJ60 is new to me... I've had it three weeks now. Temperature gauge would sit about 7/8 up the white arc but IR gun temps on the upper radiator hose and the radiator itself were 190-ish max. The coolant was low and I decided to drain and refill with NAPA Green (period correct) concentrate and distilled water, 50% ratio.

The engine is running hotter now. 190-205 across the top of the radiator, 190 on the upper radiator hose, and 210 at the top of the thermostat housing. The block, when measured around each spark plug, is 210-218. The temp sensor housing is at 235. It takes about 15 minutes of engine running and driving for those temps to be reached.

The truck has been run at various speeds for at lease one hour; it initially started to overheat but after additional burping/filling it is still hot but not overheating. I am parking it on an incline with the radiator cap as the highest point in the system, and running the engine with the front and heat on full blast. That air is hot!! I even burped from the sensor probe hole at one point. I cannot get the temps any better. New fan clutch, new thermostat, new radiator cap will be installed as soon as it gets here.

Ignoring the dash gauge - which is running at the top of the white and bottom of the red - my temps are 20-30 degrees higher than before the drain and refill. The radiator looks good, I have no idea of the history of that or the water pump at 173K but it seems coincidental that the problem started after I serviced the system. Thoughts appreciated!

Did you change your thermostat while the cooling system was drained?

On my 62, on long hill climbs, and occasionally when wheeling, the temp will spike (according to the dash gauge). But the moment the thermostat opens, temps return to "normal" running temps.

 

[OSS]

When an old thermostat fails, or begins to fail, it’s common for it to leak coolant when it shouldn’t and/or open sooner than it should.
If a tired, old thermostat opens sooner or at a lower temperature than spec, you’ll see cooler temps on the gauge.

 

[sp73]

Did you change your thermostat while the cooling system was drained?

On my 62, on long hill climbs, and occasionally when wheeling, the temp will spike (according to the dash gauge). But the moment the thermostat opens, temps return to "normal" running temps.

No I installed the new one prior to draining the system.

 

[klinetime574]

What brand of fan clutch was installed? I’ve attempted an aftermarket off-brand; I then got an AISIN and have had zero issues. Only other thing I could think of is maybe the radiator is dirty or clogged internally. I will echo that the stock gauge is not exactly exact. Granted my rig always reads appropriately when compared to my Sniper coolant temperature sensor. And I’ve gotta bring it up because reasons… was the o-ring installed on top of the thermostat?

 

[sp73]

What brand of fan clutch was installed? I’ve attempted an aftermarket off-brand; I then got an AISIN and have had zero issues. Only other thing I could think of is maybe the radiator is dirty or clogged internally. I will echo that the stock gauge is not exactly exact. Granted my rig always reads appropriately when compared to my Sniper coolant temperature sensor. And I’ve gotta bring it up because reasons… was the o-ring installed on top of the thermostat?

I used Aisin. I added the gasket, yes. I went and took the housing off just now to double check myself! I’m leaning towards the radiator myself.

 

[DrRock]

I found these engines take a while to purge all the air out of the cooling system. What does you coolant overflow tank show cold vs hot? For the first few weeks after my rebuild, I would have to top off the coolant tank as it was empty when cold. After some time it has finally settled out and maintains level between the high and low mark and fluctuates around 1” between Hot and cold. Also, how old is your radiator cap?

 

[ceylonfj40nut]

Get yourself one of these. Never had a burp issue when using it.

https://www.google.com/aclk?sa=L&ai=DChsSEwirw_D9lJWNAxWVLdQBHSb1F_AYACICCAEQGxoCb2E&co=1&gclid=Cj0KCQjwrPHABhCIARIsAFW2XBOqpUOKNRVI0kCzRXnvaEb6UvTHJ3rUoxlwdpMrmBGEQEWBJ25sN9UaAnGHEALw_wcB&sph=&cce=1&sig=AOD64_2YdCgMcswUfRtL5QIoXaJ2WFQ3xg&ctype=5&q=&ved=2ahUKEwj3xuz9lJWNAxUl78kDHVgaBkUQwg8oAHoECAsQDQ&adurl=

 

[sp73]

Installed the new radiator cap. It' s definitively better than the old one. Still overheating after 10-15 mins. I pulled the new fan clutch and just double-checked for good resitance against being turned. Re-installed it. I get an increase in air when I manipulate the throttle but I have never heard any 'roar' when driving or otherwise.

I have a CSF 2708 on order. Reading through posts on here about removing the radiator seems straightforward enough... guys mention the FSM explaining the process but I cannot locate any reference in the 2F Engine Repair Manual, Chapter 2?

 

[sp73]

Get yourself one of these. Never had a burp issue when using it.

https://www.google.com/aclk?sa=L&ai=DChsSEwirw_D9lJWNAxWVLdQBHSb1F_AYACICCAEQGxoCb2E&co=1&gclid=Cj0KCQjwrPHABhCIARIsAFW2XBOqpUOKNRVI0kCzRXnvaEb6UvTHJ3rUoxlwdpMrmBGEQEWBJ25sN9UaAnGHEALw_wcB&sph=&cce=1&sig=AOD64_2YdCgMcswUfRtL5QIoXaJ2WFQ3xg&ctype=5&q=&ved=2ahUKEwj3xuz9lJWNAxUl78kDHVgaBkUQwg8oAHoECAsQDQ&adurl=

I have one! It's great!

 

[CaptHamster]

Installed the new radiator cap. It' s definitively better than the old one. Still overheating after 10-15 mins. I pulled the new fan clutch and just double-checked for good resitance against being turned. Re-installed it. I get an increase in air when I manipulate the throttle but I have never heard any 'roar' when driving or otherwise.

I have a CSF 2708 on order. Reading through posts on here about removing the radiator seems straightforward enough... guys mention the FSM explaining the process but I cannot locate any reference in the 2F Engine Repair Manual, Chapter 2?

Is your fan clutch an AISIN brand, and is the shaft portion painted red? If so, I had terrible luck with the "stock" red AISIN fan clutches on my FJ62. They never seemed to engage when I needed them and when they did, it was kind of weak and they would kick off too easily. I never heard the fan clutch "roar" you're supposed to hear at cold startup and when it engaged. Check out my old thread about picking up a light blue fan clutch for an FJ80 (I think) and tuning it. The light blue clutches have an adjustable spring in front that lets you change what "temperature" they engage at, and you can even change out the fluid inside the make it lock up harder and stay on longer. I did both on mine, adjusted the timing of that engagement spring and added a much heavier silicone fluid inside and it works fantastic now. Pulls much more air than an electric fan ever would at full tilt. I had a couple issues with running hot that were probably related to poor maintenance on my end but the fan helped the most significantly. Since taking a thorough refresh of the cooling system with a new radiator, water pump, thermostat and hoses, things have been back to normal and the new fan clutch kicks ass.

 

[Skreddy]

I’m running a Napa fan clutch. I get the louder fan noise on startup for a minute or so and you can also hear when it’s kicking in while driving.

Did you flush the cooling system when you drained it? When I flush them, I unhook the lines to rear heater and flush it both directions with a hose, a few minutes each direction. Then, do the same with dash heater. Then flush the radiator then the engine block/head. Doesn’t have to be in that order, just isolating each component so I’m not flush everything at once.

Another spot to look is how gunked up the radiator and AC condenser fins are. It doesn’t take much to reduce the fins cooling capacity.

 

[sp73]

So I ended up dropping in a new CSF 2708 radiator. Temps finally down; gauge went to the middle for a bit but still reads high now. I’ll burp and run it more; my thought is something came loose when I did a drain/refill and clogged somewhere in the old radiator.

All the help is appreciated.