fj40 overheat at idle .. every thing checked (1 Viewer)

[shahab]

hi .
at the first please excuse my if my English is not good

I have a fj40 with 2f engine (1978)
and a/c
when I am in idel or traffic . water temp gauge climb to near H .

when I am in high way water temp is OK .
water pump is new
radiator is new
timing is OK
I have not clutch fan .
fan is new
fan shroud is OK
engine rebuilded 7 monts ago ..
temp gauge is OK
temp sensor is OK
thermostat is OK


I am confused ...
please help me .

 

[cult45]

What degree thermostat are you running, what's your average daily temp and what type of coolant?

 

[bikersmurf]

Is the Radiator stock? How many cores? Aluminum or copper?

Do you have anything blocking air flow to the radiator?

Ignition timing can affect temperature also... has it been checked? What condition is your distributor in?

Oh... and welcome. Don't worry about your English, you are doing fine.

 

[bikersmurf]

I see you already said timing was fine.

Is your A/C running when it's overheating? Is it stock (Toyota) A/C?

On my current Chevy motor, I had to switch to a somewhat smaller waterpump pulley, because it overheated @ 550 RPM, but was fine at 800 rpm. the pulley made the pump and fan turn a bit faster, and I've had no problems since then.

 

[spotcruiser]

Which fan are you running without a clutch? Is it a later, nylon fan or an early steel fan? I'm only familiar with North American trucks, so I don't know if the 2F was still using the 4-blade steel fan in 1978 outside of NA. I have no numbers, but I assume the later nylon fan moves significantly more air.

It would be good to see some photos of your engine/fan/radiator. You need 10 posts before you can attach photos (if that's still true, I'm not sure), so throw up some posts here in tech and then post some photos.

 

[cjgoode]

Did you make sure you do not have air trapped in the cooling system? You might need to burp the system.

 

[Flipper1938]

Is the vacuum advance on your distributor working?

 

[DougAustinTx]

The fellow in Iran is having the same problem that I and others have living in central Texas in the summer. I have a/c in my '79. The truck never got hot before I added the condenser in front of the radiator. I have tried both 3 and 4 core radiators (several of each), and I also get climbing water temps at idle when the ambient temp gets up around 95 degrees. The thermostat makes no difference. Timing makes no difference at idle speeds. I have replaced the aftermarket water pump with brand new Aisin.... No change. Changed the fan clutch... no help. The bottom line is that the engine needs to turn at about 1000 rpm when in traffic to get enough air across the radiator with a properly fitted fan shroud and the nylon fan blade. Once the truck gets up to 35-40 mph, the temp stabilizes at about 195 degrees. At 80 mph on the highway when ambient is 95 and above, the temp gauge will eventually crawl up to about 210 degrees.

 

[shahab]

What degree thermostat are you running, what's your average daily temp and what type of coolant?

hi
I tried with thermostat (82c) and without . no difference

daily temp is over city is 32c

I tried water ; anti freeze ; and some usual coolant but nothing difference

 

[shahab]

Is the Radiator stock? How many cores? Aluminum or copper?

Do you have anything blocking air flow to the radiator?

Ignition timing can affect temperature also... has it been checked? What condition is your distributor in?

Oh... and welcome. Don't worry about your English, you are doing fine.

hi
1-my radiator is not stock because we can not find stock radiator

2- it is 3 row copper (heavy duty ) and other people use this kind of radiator without any problem .
I had 5 to radiator before ( nothing difference)
3 - do not any thing block air flow ( only a/c condecer is front of radiator )
4- ignition timing is OK (checked with timing light)
5- my distributor is OK
6- thanks

 

[shahab]

I see you already said timing was fine.

Is your A/C running when it's overheating? Is it stock (Toyota) A/C?

On my current Chevy motor, I had to switch to a somewhat smaller waterpump pulley, because it overheated @ 550 RPM, but was fine at 800 rpm. the pulley made the pump and fan turn a bit faster, and I've had no problems since then.

hi
1 - temp gauge climb up faster when a/c is on
and climb up slower when a/c is off .
2 - I changed water pump pulley with smaller . but have not big difference .(bit better) but overheating in idle
3 - thanks

 

[shahab]

Which fan are you running without a clutch? Is it a later, nylon fan or an early steel fan? I'm only familiar with North American trucks, so I don't know if the 2F was still using the 4-blade steel fan in 1978 outside of NA. I have no numbers, but I assume the later nylon fan moves significantly more air.

It would be good to see some photos of your engine/fan/radiator. You need 10 posts before you can attach photos (if that's still true, I'm not sure), so throw up some posts here in tech and then post some photos.

1 - I did swap my radiator fan with my friends car (plastic 8 blade direct radiator fan ) but nothing difference

that is worked for my friends car perfectly

2- I will take a picture from engine and radiator and other things as soon as possible

Did you make sure you do not have air trapped in the cooling system? You might need to burp the system.

 

[shahab]

yes I am sure

 

[shahab]

Did you make sure you do not have air trapped in the cooling system? You might need to burp the system.

yes I am sure

 

[shahab]

Is the vacuum advance on your distributor working?

yes . it is work properly

 

[cult45]

Well s*** dude I got no idea. Sorry!

 

[AussieHJCruza]

Are you thinking it's overheating based on the standard, factory fitted temperature gauge? If you are, I would suggest getting an aftermarket one that shows actual temperatures, not just a needle and lines. It could be that the standard gauge is not working correctly.

 

[shahab]

Are you thinking it's overheating based on the standard, factory fitted temperature gauge? If you are, I would suggest getting an aftermarket one that shows actual temperatures, not just a needle and lines. It could be that the standard gauge is not working correctly.

it is so hot ..
I checked coolant temp with aftermarket too

 

[AussieHJCruza]

That's strange then. Are your Air:Fuel ratios in order?

 

[honk]

Avoid sitting at idle in traffic.

If you are forced to idle in traffic do these two things: 1) raise the engine RPM to increase airflow across the radiator for the duration of your traffic. 2) turn off the air conditioning.

There is nothing wrong with the truck other than it was not designed with the possibility of prolonged traffic stoppages a factor of it's design usage.

Consider a newer vehicle designed after such realities became common factors of it's potential usage.