1 minute ago, 72 Datsun 240z said:

I paid a Camaro mechanic to solve this issue and he has done all possible external tests. Unfortunately, heat problem is still there. He did noticed 2 things:

1. Oil pressure very low. It only rises when you accelerate.

2. Cylinder 4th could have a problem as measurement are not within 10 percent.

Ill do the radiator test tomorrow. How long shall i run the engine at idle withe the cap off?

Your oil pressure is low because your oil level is low and looks like it came out of the labrea tar pits, 2000 years ago. I'm not sure what you mean by 10%, but I'm assuming its compression related. Neither of those are related to your temp issue. Let's work on the temp issue then deal with that afterwords.

Since you don't have a thermometer in the engine, no need to let the engine sit and run for a while to warm up. Literally pop the cap off, turn it on and look if the coolant is circulating, then press down on the throttle linkage to rev the engine to see if the coolant also accelerates. Start to finish this is less than a 2 minute job.

The nissan oil gauges tend to display low. That is ok. They naturally increase the pressure when you rev them.

Until

Posted the pic. Until you do this mod you don’t have a clue what the pressure is. Takes research and find the parts.

I thought about suggesting that but it seems so challenging to even get the simple things done, I didn't want to complicate things.

I have done a similar mod in the past and found that even though the gauge showed almost no pressure at idle it was actually about 30 pounds

On 3/25/2026 at 10:12 PM, chaseincats said:

yep that's the Aisin one - that didn't help me, only the one I linked to on Amazon brought my temp gauge to normal

On 4/22/2026 at 10:10 PM, chaseincats said:

Your oil pressure is low because your oil level is low and looks like it came out of the labrea tar pits, 2000 years ago. I'm not sure what you mean by 10%, but I'm assuming its compression related. Neither of those are related to your temp issue. Let's work on the temp issue then deal with that afterwords.

Since you don't have a thermometer in the engine, no need to let the engine sit and run for a while to warm up. Literally pop the cap off, turn it on and look if the coolant is circulating, then press down on the throttle linkage to rev the engine to see if the coolant also accelerates. Start to finish this is less than a 2 minute job.

Im taking the car tomorrow to a radiator shop. Any thought on a good temp sensor for my 72 240z? Something that could give me an accurate reading?? Maybe made in Japan?

https://zcardepot.com/products/coolant-temperature-sensor-for-gauge-japan-240z-260z-280z#:~:text=$11.99,operates%20the%20coolant%20temperature%20gauge.

You continue to ignore any suggestion that’s being offered and don’t come back with results. Therefore I am bowing out of giving any suggestions.

4 hours ago, 72 Datsun 240z said:

Im taking the car tomorrow to a radiator shop. Any thought on a good temp sensor for my 72 240z? Something that could give me an accurate reading?? Maybe made in Japan?

https://zcardepot.com/products/coolant-temperature-sensor-for-gauge-japan-240z-260z-280z#:~:text=$11.99,operates%20the%20coolant%20temperature%20gauge.

I will not be responding to your posts until you try the tests I detailed many times. Sorry.

10 hours ago, chaseincats said:

I will not be responding to your posts until you try the tests I detailed many times. Sorry.

Test done! Water is flowing! I even installed a temperature cap and it remains in 80 degrees under heavy traffic! I guess sensor or gauge is not reading correctly! Any advice?

1 minute ago, 72 Datsun 240z said:

Test done! Water is flowing! I even installed a temperature cap and it remains in 80 degrees under heavy traffic! I guess sensor or gauge is not reading correctly! Any advice?

Ok, thanks for doing the test, now I'll move on - funny how you get a solution when you listen to us, huh.

You have 1 test left - this will tell you if its the sensor OR the gauge that need to be replaced.

Unplug that yellow wire you took a picture of and ground it against the engine block using an alligator clip/piece of wire/whatever. Touch one end of the alligator clip to the engine block (or any groundable area), touch the other end of the alligator clip to the yellow wire's metal connector, turn the ignition key to 'on', and look at the gauge:

• IF your gauge is good, the gauge's needle will move all the way right (250+). If that happens, your gauge is good, and your temp sensor needs to be replaced.

• If the gauge does NOT move all the way to the right it is probably your gauge. Replace the temp sender too though.

This is the final test - it WILL give you a final answer.

Edited April 25Apr 25 by chaseincats

3 hours ago, chaseincats said:

Ok, thanks for doing the test, now I'll move on - funny how you get a solution when you listen to us, huh.

You have 1 test left - this will tell you if its the sensor OR the gauge that need to be replaced.

Unplug that yellow wire you took a picture of and ground it against the engine block using an alligator clip/piece of wire/whatever. Touch one end of the alligator clip to the engine block (or any groundable area), touch the other end of the alligator clip to the yellow wire's metal connector, turn the ignition key to 'on', and look at the gauge:

• IF your gauge is good, the gauge's needle will move all the way right (250+). If that happens, your gauge is good, and your temp sensor needs to be replaced.

• If the gauge does NOT move all the way to the right it is probably your gauge. Replace the temp sender too though.

This is the final test - it WILL give you a final answer.

Gauge needle moved all the way to the right till 250F when doing this test. What next?? I need a high quality japanese made sensor. Maybe nissan made in Japan.

Start researching, you seem to want everyone to do the research for you.