First check the coolant level before starting it. I bet it's low...top it off...

Don't let it idle with out keeping an eye on the gauge. If it gets to 3/4 of the way up, try touching the upper radiator hose. Don't get burnt!!! and don't stick you hand in the fan!!! If you can touch it, then check the thermostat housing. Your hands can't handle temps that are truely above half way on the temp gauge. If you can touch those two and the valve cover the engines probably not overheating it is seeing steam at the thermostat.

You are best off to not let the gauge get into the red. If it gets hot, let it cool off and add some coolant. When it get's half way rev it a little bit to move the water through the engine to flush out the air

Report back exactly what you see, did and how you did it. We will go from there...

In the morning when you first crank it, remove the radiator cap. Let the motor get up to temp. You should see coolant flowing across the radiator. It will burp some fluid out and then settle down. The coolant level should be at the bottom of the filler hole and moving constantly, even more when you rev the  motor.

I can assure you blocking off the flow through the intakes will not increase the coolant temp. My car and dozens of others have this done without problem. The '70 & '71s didn't have that coolant circuit at all.

My bet is low coolant level and air in the system.

You need a meat thermometer in the radiator while the car warms up. They're a couple of dollars here and available at grocery stores. You can prop them around the thermostat housing as well as the cylinder head for a true temperature reading. Your Mom probably has one in a kitchen drawer.

Seems like you've been down this road before.  Did you ever correct the problem or just move on to another problem as usual?

 

13 hours ago, jalexquijano said:

He did not test it at all!  He says he followed the advice and pictures i sent him and that the car had no coolant on the system! Very rude person!

Take off the radiator cap and take a picture of the coolant.  Just to be sure that there is coolant now.

problem was low coolant. I went and bought a gallon of coolant until i reached to the level of the filler. Temperature mantains at 1/2 while driving but increases until 3/4 at idle with lights on and AC on. I also noticed that after leaving it on idle for more than 15 minutes, rpm dropped randomly from 900 to 600 RPM. However, engine did not stalled. There are some bubbles on the glass fuel filter.

Edited December 19, 20168 yr by jalexquijano

I took some pictures and left the car idling for 15 minutes. Engine still drops rpm to 500 randomly but does not shut off. Once i opened the engine bay. i saw some bubbles on the glass fuel filter. A friend of mine thinks the car needs valve adjustment on cold so the idle gets less lumpy.

A bunch of coolant came out while the mechanic was messing with the hoses and he didn't bother to refill it ? Wow what a kook !

Notice that the earlier photo posted of the passenger side of the engine shows shows a short piece of hose with plugged end (why is the clamp on the end turned so you can't tighten it ?), but the later photo shows the side hose connected with the heater capped? Not that it makes a difference.

Don't use those rubber caps, they deteriorate and fall apart quickly from the heat. Use a tapered rubber plug tapped into the tube instead, and  clamp a silicon cap (mcmaster-carr) over it, OK?

Cooling system uses all BSPT fittings. Use NPT and you'll bugger the threads. If you're ok with that, fine, if it doesn't leak.

Temp gauge looks ok in the last picture of it.

A bunch of coolant came out while the mechanic was messing with the hoses and he didn't bother to refill it ? Wow what a kook !

Notice that the earlier photo posted of the passenger side of the engine shows shows a short piece of hose with plugged end (why is the clamp on the end turned so you can't tighten it ?), but the later photo shows the side hose connected with the heater capped? Not that it makes a difference.

Don't use those rubber caps, they deteriorate and fall apart quickly from the heat. Use a tapered rubber plug tapped into the tube instead, and  clamp a silicon cap (mcmaster-carr) over it, OK?

Cooling system uses all BSPT fittings. Use NPT and you'll bugger the threads. If you're ok with that, fine, if it doesn't leak.

Temp gauge looks ok in the last picture of it. Edit: no it doesn't.

Edited December 19, 20168 yr by Stanley
changed my mind

And go to local Nissan parts department and get a real Nissan thermostat for it.

Siteunseen wins cheeseburger  for correct guess.

1 hour ago, Stanley said:

Siteunseen wins cheeseburger  for correct guess.

I'm going to hand out a few of these badges too

3 hours ago, Stanley said:

And go to local Nissan parts department and get a real Nissan thermostat for it.

Which thermostat? I need the one for tropical hot weather!

 

 

I took some pictures and left the car idling for 15 minutes. Engine still drops rpm to 500 randomly but does not shut off. Once i opened the engine bay. i saw some bubbles on the glass fuel filter. A friend of mine thinks the car needs valve adjustment on cold so the idle gets less lumpy.