1991 LC over heating when AC on ... PLEASE HELP!

[Vavrinyuk]

Hello Everyone

I need some help with my 1991 Land Cruiser. I had my water pump replaced because my old one was leaking so since I had to take front end apart I decided to change water pump, thermostat, fan clutch, radiator, radiator hoses all part where NEW Toyota OEM. I also had radiator fluid flush and replaced with new Toyota Red Coolant OEM. To have no cooling issues.

BUT

When I run the LC with AC OFF it holds temp normal no problems. When it's around 90+ fahrenheit outside and I am standing on a light for more then 5 minutes with AC ON my temperature gauge starts to climb and over heat. I then have to turn off AC drive around to cool it down then I can run it again.

Can anyone help me figure out what's causing the problem?

*side note I did notice when the truck stands for a few days without running there is a small water puddle the size of a golf ball in diameter. But when it's running no leaks or drops. I think I need to tighten up water pump bolts a little bit more for good water pump seal to engine.

Thank You for the help!

 

[450LX]

You might have an "air bubble" in your cooling system. With your engine cold undo your radiator cap and put in a funnel and top off your coolant. Start the truck and let it run until the thermostat opens up with the radiator cap off. Rev it up periodically until no more bubbles are coming out into the funnel and the heater is blowing hot (maybe 20min). I'm sure there are other ways to 'burp It', but thats how i do it. How much coolant did you put in initially? Sometimes you may only get 2 gallons in, but the system holds 3.5, hence the bubble. You did a 50/50 mix right?

 

[Vavrinyuk]

You might have an "air bubble" in your cooling system. With your engine cold undo your radiator cap and put in a funnel and top off your coolant. Start the truck and let it run until the thermostat opens up with the radiator cap off. Rev it up periodically until no more bubbles are coming out into the funnel and the heater is blowing hot (maybe 20min). I'm sure there are other ways to 'burp It', but thats how i do it. How much coolant did you put in initially? Sometimes you may only get 2 gallons in, but the system holds 3.5, hence the bubble. You did a 50/50 mix right?

Thanks for the reply! I'll try that out burping the system. I did do 50/50 as best I could I did clean the block with water when I had the water pump off so there was some water in the system I tried my best to add in enough Coolant to match.

 

[LS1FJ40]

Do you get the ROAR of the fan when you start your truck? It sounds like a DC10 engine. Then it settles down to normal? It should do this.

Have you checked the thermostat to make sure it is opening? Boil water in a pan with the thermostat in it. It should open around 170 degrees IIRC.

My experience is that air will escape in short order even if you don't burp it.

 

[SUMMIT CRUISERS]

If the engine temps are fine with the AC off then your system wont't have air in it causing an issue with the AC on. I would suspect the fan not roaring like @LS1FJ40 mentioned. It should also roar while idling with the AC on with ambient temps above 90. I fought this years ago with my then wife's 92. I installed GTP hood vents, an auxiliary pusher fan, new fan clutch and finally upgraded the fan clutch fluid with 15K CST silicone fluid which fixed the issue. Here's a thread where to buy:
Source for 15k CST Silicone Oil

 

[jonheld]

There hasn't been an OEM radiator for the 3FE available in the US for years. I'm pretty sure I bought the last one.
That said, you should make sure the plastic fan shroud is in place and that it has a tight seal to the radiator.
The fan clutch should have a green (aqua) hub if it is OEM and the correct one for the 3FE.

Did you have any cooling issues before replacing parts?

 

[Tools R Us]

Are both gaskets in place on the thermostat? If the upper is missing, can cause the issue you are seeing.

 

[ward93]

Since when were there more than one gasket? There is only the one on top and then the housing gasket. Or am I mistaken

 

[jdayment]

Since when were there more than one gasket? There is only the one on top and then the housing gasket. Or am I mistaken

There should be one for the housing and one for the thermostat itself

 

[ward93]

Thanks that's what I thought

 

[gummycarbs]

I've been diagnosing a mild overheating problem on a different vehicle. I'd done the fan clutch and water pump (but not the thermostat, I don't think).

Something I noticed is that using an IR heat sensor on the radiator, I was only seeing temperatures around 140 - 170 while the gauge read 210+. Now, I don't know how hot a radiator should really get, particularly since I'm really just measuring the temperature of the outer fins, but that seems low. And if the radiator isn't getting hot enough, then the fan clutch will never get hot enough to engage (IIRC, they're calibrated to something like 30 degrees lower to account for the air gap).

Anyway, I'm currently doing a heavy flush on that cooling system, and a new thermostat is going in. My point being: maybe your radiator is still clogged.

Also, for what it's worth, I've only read good things about CSF all-metal radiators.

 

[Raultlc]

Hello Everyone

I need some help with my 1991 Land Cruiser. I had my water pump replaced because my old one was leaking so since I had to take front end apart I decided to change water pump, thermostat, fan clutch, radiator, radiator hoses all part where NEW Toyota OEM. I also had radiator fluid flush and replaced with new Toyota Red Coolant OEM. To have no cooling issues.

BUT

When I run the LC with AC OFF it holds temp normal no problems. When it's around 90+ fahrenheit outside and I am standing on a light for more then 5 minutes with AC ON my temperature gauge starts to climb and over heat. I then have to turn off AC drive around to cool it down then I can run it again.

Can anyone help me figure out what's causing the problem?

*side note I did notice when the truck stands for a few days without running there is a small water puddle the size of a golf ball in diameter. But when it's running no leaks or drops. I think I need to tighten up water pump bolts a little bit more for good water pump seal to engine.

Thank You for the help!

Hi bro,

Did you solved this? Im facing the same issue with an also 3fe 80 series.

 

[Marco Lau]

If the engine temps are fine with the AC off then your system wont't have air in it causing an issue with the AC on. I would suspect the fan not roaring like @LS1FJ40 mentioned. It should also roar while idling with the AC on with ambient temps above 90. I fought this years ago with my then wife's 92. I installed GTP hood vents, an auxiliary pusher fan, new fan clutch and finally upgraded the fan clutch fluid with 15K CST silicone fluid which fixed the issue. Here's a thread where to buy:
Source for 15k CST Silicone Oil

same here.....temp would start to climb on stop and go traffic with AC on when it was bone stock. Replaced alum. radiator, hoses, WP, 15k fluid and adjusted timing on the OEM Aisin fan clutch, added hood vents, installed 2 monster pusher fans in front of condensor and oil cooler...now it will never go over 200F, fully loaded, pulling steep grade, sit in traffic for hours, etc. Good luck....your glad you have a 3FE....or else you are probably looking at a new head otherwise...

 

[Raultlc]

Hello Everyone

I need some help with my 1991 Land Cruiser. I had my water pump replaced because my old one was leaking so since I had to take front end apart I decided to change water pump, thermostat, fan clutch, radiator, radiator hoses all part where NEW Toyota OEM. I also had radiator fluid flush and replaced with new Toyota Red Coolant OEM. To have no cooling issues.

BUT

When I run the LC with AC OFF it holds temp normal no problems. When it's around 90+ fahrenheit outside and I am standing on a light for more then 5 minutes with AC ON my temperature gauge starts to climb and over heat. I then have to turn off AC drive around to cool it down then I can run it again.

Can anyone help me figure out what's causing the problem?

*side note I did notice when the truck stands for a few days without running there is a small water puddle the size of a golf ball in diameter. But when it's running no leaks or drops. I think I need to tighten up water pump bolts a little bit more for good water pump seal to engine.

Thank You for the help!

Hi bro,

Im facing the same problem, but i didnt replaced anything yet, the fan clutch, wp and fan shrouf are on the way. Did you solved this?

 

[cietom]

same here.....temp would start to climb on stop and go traffic with AC on when it was bone stock. Replaced alum. radiator, hoses, WP, 15k fluid and adjusted timing on the OEM Aisin fan clutch, added hood vents, installed 2 monster pusher fans in front of condensor and oil cooler...now it will never go over 200F, fully loaded, pulling steep grade, sit in traffic for hours, etc. Good luck....your glad you have a 3FE....or else you are probably looking at a new head otherwise...

Question, where did you get your push fans? I'll do a search about the fan clutch fluid too, this is the first I heard you could even change it haha, all my previous cars have had electric fans. I have trouble with my 3FE temps climbing when stopped at lights for more than a few minutes, in traffic or in really long drive-thru lines. Doesn't help that I'm in Phoenix and it can be over 100 outside even at night.

New radiator, hoses and thermostat, and then I put in fresh Toyota red. Everything is OEM except the radiator itself. Temps are fine when driving even on our 117 degree days, but idling is beating my ass hahaha.

 

[Marco Lau]

G

Question, where did you get your push fans? I'll do a search about the fan clutch fluid too, this is the first I heard you could even change it haha, all my previous cars have had electric fans. I have trouble with my 3FE temps climbing when stopped at lights for more than a few minutes, in traffic or in really long drive-thru lines. Doesn't help that I'm in Phoenix and it can be over 100 outside even at night.

New radiator, hoses and thermostat, and then I put in fresh Toyota red. Everything is OEM except the radiator itself. Temps are fine when driving even on our 117 degree days, but idling is beating my ass hahaha.

Get the OE Aisen fan clutch and change out the fluid to 10-15k and start from there.

 

[jonheld]

^^^^^^^THIS^^^^^^^
The correct fan clutch for the 3FE is the Aisin FCT-049 and has a green/aqua colored mounting base. It can be purchased through Amazon and a variety of others.

 

[cietom]

^^^^^^^THIS^^^^^^^
The correct fan clutch for the 3FE is the Aisin FCT-049 and has a green/aqua colored mounting base. It can be purchased through Amazon and a variety of others.

Sweet, just ordered one! Also got some 15k cst fluid coming in as well, so hopefully this addresses my traffic overheating and A/C not blowing cold at stops! I'll report back once it's all installed.

 

[Raultlc]

You guys, i have a question, how many rows has the original radiator for the 3fe?. I have an aftermarket one with just 2.

 

[jonheld]

Sweet, just ordered one! Also got some 15k cst fluid coming in as well, so hopefully this addresses my traffic overheating and A/C not blowing cold at stops! I'll report back once it's all installed.

You might want to try simply replacing the fan clutch with the new one before modifying it with higher viscosity oil. The green hub fan clutch is a different design internally with more fluid shearing surfaces than the blue hub found on the 1FZ-FE engines. In its new stock form it is pretty robust.