Cooling system help and bushing

[apachiestrike95]

I’ve got a 1985 720 4x4 with the z24 carbureted motor. It’s got an all aluminum 4 core radiator, twin 13 inch electric fans, an 18psi radiator cap and new coolant and hoses. But when it idles for long periods of time or when I’m stuck In traffic the needle goes above the half mark. I just replaced the cap yesterday and added a second fan Saturday. When I drive it, it’s right in the middle of half and the first line. But it only heats up on idle. Any help is appreciated. And one other thing. My transfer case bushing are shot and I can’t seem to find them anywhere. 

 

[Charlie69]

Have you changed the thermostat?

 

These trucks come stock with a coolant recovery tank.

[datzenmike]

Generally just a hair above 1/2 is perfect but 3/4 is fine certainly for such a short time. Obviously two fans are not enough when stopped at idle and vehicle speed makes a big difference even though the engine is working harder. If you want some comfort borrow an infra red gun and 'shoot' the thermostat housing while idling and see what the temperature really is at 1/2 and when the fans come on. I assume you have a switch and the fans are mostly off or you may as well keep the stock mechanical fan.

 

My 710 has twin Subaru fans one pushing air through from the front and one pulling air through from behind. They can't sit side by side so I did it this way with about 4" of overlap. When driving it run a hair above 1/2 so 180-185F what the thermostat is rated at and fans never come on. If idling or climbing hills long enough, the gauge goes to almost 3/4 (just above 2/3s) and the temperature switch turns the fans on. I think the switch is from a '90s 200sx that turns the fans on at 190F?. At idle they run for less that 10 seconds and then shut off for 40. The temp switch is in the lower rad hose. 

[apachiestrike95]

the fans are on constantly. and what temperature should i be looking for? also i havent replaced the thermostat on it 

[bottomwatcher]

Well you have changed the cap next is to put in a QUALITY thermostat. Search on her the topic has been covered adnauseum.

[apachiestrike95]

7 minutes ago, bottomwatcher said:

Well you have changed the cap next is to put in a QUALITY thermostat. Search on her the topic has been covered adnauseum.

what was the name of the topic so i can search it up?

 

[apachiestrike95]

1 hour ago, datzenmike said:

Generally just a hair above 1/2 is perfect but 3/4 is fine certainly for such a short time. Obviously two fans are not enough when stopped at idle and vehicle speed makes a big difference even though the engine is working harder. If you want some comfort borrow an infra red gun and 'shoot' the thermostat housing while idling and see what the temperature really is at 1/2 and when the fans come on. I assume you have a switch and the fans are mostly off or you may as well keep the stock mechanical fan.

 

My 710 has twin Subaru fans one pushing air through from the front and one pulling air through from behind. They can't sit side by side so I did it this way with about 4" of overlap. When driving it run a hair above 1/2 so 180-185F what the thermostat is rated at and fans never come on. If idling or climbing hills long enough, the gauge goes to almost 3/4 (just above 2/3s) and the temperature switch turns the fans on. I think the switch is from a '90s 200sx that turns the fans on at 190F?. At idle they run for less that 10 seconds and then shut off for 40. The temp switch is in the lower rad hose. 

my fans are running constantly when the truck starts. what temperature should both thermostat and hoses really be at?

[jagman]

I just changed thermostats and the one I am using now is part number 21200-80w00.  which is the lowest temp that Nissan sells and it works for me. The old one is a higher temp opening and the truck ran hot at idle and pulling.  The cap I am using is a 13 pound rated cap.  My guage now reads at just below the thermometer base on the guage.

[bottomwatcher]

Page 5

[datzenmike]

3 hours ago, apachiestrike95 said:

the fans are on constantly. and what temperature should i be looking for? also i havent replaced the thermostat on it 

 

The advantage of electric fans are they are only on when needed. Vehicle speed over 30 will usually be enough to keep the engine cool. A temperature switch and a relay with a fuse and it's quieter and the fan will last longer. Like I said, if the fan is on constantly you may as well have left the mechanical fan on.

 

Any overheating condition I ALWAYS just replace the thermostat and be done with it. If it doesn't help I have a good spare.

 

 

 

2 hours ago, jagman said:

I just changed thermostats and the one I am using now is part number 21200-80w00.  which is the lowest temp that Nissan sells and it works for me. The old one is a higher temp opening and the truck ran hot at idle and pulling.  The cap I am using is a 13 pound rated cap.  My guage now reads at just below the thermometer base on the guage.

 

You need to be running at or very near the 1/2 point on the 'run range'. Lower than this the engine was not designed to run at it's most efficient. Ideally 185F gives the longest engine life, best mileage and performance.