Cooling system cry for help

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SciroccoDamonte

SciroccoDamonte

Joined
Jun 16, 2024
Threads
12
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55
Location
eureka CA
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I’m a bit lost on what to do, my cooling system on my 1991 Toyota landcruiser just cannot keep up. I’ve done everything I can think of. 4 core aluminum radiator, thicker fan clutch oil, auxiliary electric fan, spacers to gap the hood away from the body, coolant flush, new water pump. Everything but doing a little dance and performing a ritual. But it just can’t keep up, at slow speeds rock crawling, mountain passes, if it’s above 90 degrees then it gets hot in any circumstance.

This in turn makes my ac system so hot that it has way too much pressure and hardly works. So then I’m stuck with a hot truck and then a hot cab.

If anyone has any idea what could possibly be wrong with this truck. Please let me know, it has 300k miles on it so if that’s just the way these trucks are when they are then that’s what it is. I just don’t know enough people that own them to be able to compare at all.

I’m looking into a smaller fan clutch pulley if anyone has any recommendations. That’s the last thing i can think of.
 
The oil in the fan clutch is only one part of the set up and if you didn't also calibrate the port opening temps then it's possible that it's not circulating oil until the engine temps are too high.

You want the fan to engage early enough to keep the engine cool, but not so early that you are overcooling or running the fan hard with an only partially open or a closed thermostat.

You can search the forums for information about port opening temps and how to set them. If you don't find the exact info for your fan clutch you should be fine making small adjustments until you get where you want to go. You can use a double boiler, candy thermometer and then adjust how open the ports are at certain temps until you get the fan engagement where you need it. You shouldn't need to tweak the adjustment more than a few times and it's not too hard to remove the clutch/fan once you get used to doing it.
 
SciroccoDamonte said:
if it’s above 90 degrees then it gets hot in any circumstance.
Click to expand...
how hot? its best to have numbers when trying to solve this problem.

no there are plenty of 300k+ trucks that run cool

do you have any coolant consumption? have you passed a block test?

do you have foam around the radiator?
 
The 3FE produces a max of 155 hp (when it was new).
I find it difficult to believe that a well maintained OEM cooling system has difficulty keeping up.
I've owned my 1991 FJ80 for 28 years. It dragged a trailer round trip from Jersey to Moab twice without complaint, and was my daily driver since new. It now has 320K+ miles and runs like a top for it's second owner.
The only time I had cooling system issues, it was due to a tired fan clutch.

Some things to consider (part #s for the 3FE):
The proper OEM fan clutch for the 3FE is the Aisin FCT-049. It has an aqua colored hub and is robust out of the box.
***** DO NOT USE AN AFTERMARKET FAN CLUTCH *****
The proper fan blade for the 3FE is the Aisin FNT-018.
***** DO NOT USE AN AFTERMARKET FAN BLADE *****
There MUST MUST MUST be a fan shroud installed (16711-61260) and it should be sealed to the radiator to aid in airflow. The picture below is for the 1FZ-FE, but you get the idea.
The OEM thermostat (90916-03052) along with the gasket that sits on top of the thermostat (90430-43002) and the gasket between the 2 halves of the housing (16341-61030) should be replaced.
The OEM radiator cap is critical for proper cooling (16401-54750).
Pressure test the system. It should be able to hold 13 psi all day.
There should be foam around the perimeter of the radiator that seals it to the AC condenser coil.
The thin belly pan that mounts above the relay rod should be in place.

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jpoole said:
The oil in the fan clutch is only one part of the set up and if you didn't also calibrate the port opening temps then it's possible that it's not circulating oil until the engine temps are too high.

You want the fan to engage early enough to keep the engine cool, but not so early that you are overcooling or running the fan hard with an only partially open or a closed thermostat.

You can search the forums for information about port opening temps and how to set them. If you don't find the exact info for your fan clutch you should be fine making small adjustments until you get where you want to go. You can use a double boiler, candy thermometer and then adjust how open the ports are at certain temps until you get the fan engagement where you need it. You shouldn't need to tweak the adjustment more than a few times and it's not too hard to remove the clutch/fan once you get used to doing it.
Click to expand...
Hmmm interesting I had no idea about that, without adjusting that the fan clutch does feel much stiffer. I’ll look into it, thanks
 
TheBussman said:
how hot? its best to have numbers when trying to solve this problem.

no there are plenty of 300k+ trucks that run cool

do you have any coolant consumption? have you passed a block test?

do you have foam around the radiator?
Click to expand...
I don’t have exact numbers but at low revs around town the gauge will slowly climb above center to about 3/4 to the red. It’s got good compression in all cylinders and no consumption. No foam either.
 
jonheld said:
The 3FE produces a max of 155 hp (when it was new).
I find it difficult to believe that a well maintained OEM cooling system has difficulty keeping up.
I've owned my 1991 FJ80 for 28 years. It dragged a trailer round trip from Jersey to Moab twice without complaint, and was my daily driver since new. It now has 320K+ miles and runs like a top for it's second owner.
The only time I had cooling system issues, it was due to a tired fan clutch.

Some things to consider (part #s for the 3FE):
The proper OEM fan clutch for the 3FE is the Aisin FCT-049. It has an aqua colored hub and is robust out of the box.
***** DO NOT USE AN AFTERMARKET FAN CLUTCH *****
The proper fan blade for the 3FE is the Aisin FNT-018.
***** DO NOT USE AN AFTERMARKET FAN BLADE *****
There MUST MUST MUST be a fan shroud installed (16711-61260) and it should be sealed to the radiator to aid in airflow. The picture below is for the 1FZ-FE, but you get the idea.
The OEM thermostat (90916-03052) along with the gasket that sits on top of the thermostat (90430-43002) and the gasket between the 2 halves of the housing (16341-61030) should be replaced.
The OEM radiator cap is critical for proper cooling (16401-54750).
Pressure test the system. It should be able to hold 13 psi all day.
There should be foam around the perimeter of the radiator that seals it to the AC condenser coil.
The thin belly pan that mounts above the relay rod should be in place.

View attachment 4158615
Click to expand...
That’s my thinking too, how could it possibly be so hot. It’s only 155 hp! I do have a proper Asin clutch with thicker oil like I said. I have a good shroud with closed cell foam to seal it to the radiator. Factory fan aswell. I definitely could get a pressure test for the system so I’ll look into that. Thanks for the input
 
SciroccoDamonte said:
Hmmm interesting I had no idea about that, without adjusting that the fan clutch does feel much stiffer. I’ll look into it, thanks
Click to expand...
last clutch i opened hoping i could just change the fluid but the spring must have been messed up and the valves were almost 90 degrees off! def check on that. i had to replace the whole clutch.
 
The key points have been hit by others above.

It would be worth verifying coolant temps with a separate guage, or an infrared heat gun and not relying on the factory gauge.
Typically if the factory gauge has hit the red, you're already in a overheating sutuation.

I also spent time adjusting the valve in an oem fan clutch and this with fresh silicone oil definitely made a difference. Unfortunately my o ring seal failed and I lost all the fresh oil a few weeks later.

90⁰ f is a normal spring day in many parts of the world. If everything is up to scratch, you definitely shouldn't have an overheating issue
 
Note, I and others have had new, off-the-shelf Aisin fan clutches that opened at too high of a temp. On my 80 I initially just changed the oil but had the AC cut-off soon after installing the new clutch due to high temps. Tuned the clutch opening temps and haven't had the AC cut off due to high temps since, with over 100k miles including Summer towing, etc.

On the later, US 80 series (1FZFE) the AC cuts off around 220 degrees Farenheit so that can be another data point on you actually running hot.
 
mudgudgeon said:
The key points have been hit by others above.

It would be worth verifying coolant temps with a separate guage, or an infrared heat gun and not relying on the factory gauge.
Typically if the factory gauge has hit the red, you're already in a overheating sutuation.

I also spent time adjusting the valve in an oem fan clutch and this with fresh silicone oil definitely made a difference. Unfortunately my o ring seal failed and I lost all the fresh oil a few weeks later.

90⁰ f is a normal spring day in many parts of the world. If everything is up to scratch, you definitely shouldn't have an overheating issue
Click to expand...
Copy that, is there a good resource that shows how to adjust the fan clutch? That’s a little bit past my home mechanic knowledge.
 
jpoole said:
Note, I and others have had new, off-the-shelf Aisin fan clutches that opened at too high of a temp. On my 80 I initially just changed the oil but had the AC cut-off soon after installing the new clutch due to high temps. Tuned the clutch opening temps and haven't had the AC cut off due to high temps since, with over 100k miles including Summer towing, etc.

On the later, US 80 series (1FZFE) the AC cuts off around 220 degrees Farenheit so that can be another data point on you actually running hot.
Click to expand...
I think it’s possible my off the shelf fan clutch I bought was like you said opened at too high of a temp I figured thicker oil would just blanket solve the problem by being way stiffer.

The ac issue I’ve been having is a head scratcher, the engagement clutch on the ac pump clacks on and off, usually with matching rev up rev down of the motor. Like you may have read I don’t have an exact number for my engine temps so it’s hard to say when the ac is failing.

Thanks for the reply
 
SciroccoDamonte said:
Copy that, is there a good resource that shows how to adjust the fan clutch? That’s a little bit past my home mechanic knowledge.
Click to expand...

There is an old thread (linked) discussing modifications to the blue fan hub, you'll have to read several pages in.
It's not difficult, but at the same time, it will take a bit of figuring it out.

Thread 'Blue fan clutch mod...Thread has gone to hell, read at your own risk' Blue fan clutch mod...Thread has gone to hell, read at your own risk - https://forum.ih8mud.com/threads/blue-fan-clutch-mod-thread-has-gone-to-hell-read-at-your-own-risk.102633/

Or @landtank was/ is selling these already modified.
I'm not super familiar with the 3FE, so toiling need to check if he had one for your engine, or if the blue hub will work with 3fe.
I believe the difference in the different colored hubs is primarily the snout length is different to suit different physical engine configurations, but @landtank or others might be able to confirm this
 
SciroccoDamonte said:
I think it’s possible my off the shelf fan clutch I bought was like you said opened at too high of a temp I figured thicker oil would just blanket solve the problem by being way stiffer.

The ac issue I’ve been having is a head scratcher, the engagement clutch on the ac pump clacks on and off, usually with matching rev up rev down of the motor. Like you may have read I don’t have an exact number for my engine temps so it’s hard to say when the ac is failing.

Thanks for the reply
Click to expand...
AC is supposed to turn off during overheating at least on the 1fz. on a unmodified temp gauge 3/4 is really hot. if you every need to replace your cluster light bulbs the temp gauge mod is highly recommended.
 
SciroccoDamonte said:
Cool thanks
Click to expand...
I would not recommend elec. fan if you are having cooling issues. I did the elec. fan conversion for another reason. My 20k green Aisin hub with timing adjust, 2 core alum. radiator, and sealed shroud is more powerful than my 4000cfm unit. But the Elec fan is king when it comes to regulating AC, and 4Lo rock crawling the temp stays nice and cool since it is not dependent on engine speed. BTW, don't listen to FJ80Oregon, he's been an instigator for ages and the best thing is to stop paying him little to no attention. ;)
 
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SciroccoDamonte said:
I don’t have exact numbers but at low revs around town the gauge will slowly climb above center to about 3/4 to the red. It’s got good compression in all cylinders and no consumption. No foam either.
Click to expand...
at 3/4 you are looking at 225F-230F. and your tranny temp is right around that.
 
The temp gauge mod is also known as the Raventai MOD, and adds a diode (?) on the back of the temp gauge to allow for linear needle movement to engine temp to avoid the needles HUGE dead-zone in the middle of the gauge (*which isn't a calibrated instrument to temp °F, I might add...).
 
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