Another SR20det Overheating Problem - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

mreid · 04-30-2017, 10:45 PM

I'm new to the SR, and hate to bring this up again because it's been hashed over so many times, but I'm stuck. Here are some of the details:

SR20det notchtop - putting on break-in miles, but so far seems to run fine - except the overheating problem.

New radiator, water pump, hoses, OEM thermostat, fans, etc.

I've burped, and purged air multiple times based on several threads I've read and the FSM. I just don't think there is any air in the system.

I'm not losing any coolant - no bubbles in the radiator - no white smoke.

When the car is idling, everything seems fine. It warms up, I see coolant flow through the radiator, fans come on, the temp drops, and the cycle repeats. It never overheats while idling.

After driving for several miles, it eventually will overheat. If I pull over and sit idling for 5 minutes, the temp drops down to where it should be - until I start driving again.

Any suggestions would be much appreciated!!!

bfellini · 05-01-2017, 12:09 AM

Which ECT sensor (the single wire) is installed on the motor?

Are both radiator hoses similar temp when you experience the issue? Be careful not to burn yourself when checking!

Sent from my iPhone using Tapatalk

mreid · 05-01-2017, 12:40 AM

bfellini - The ECT is the older style spade lug, and I've replaced it. There is also an Autometer temp sensor in the upper hose.

I don't know exactly what the difference in hose temp is when this happens. By the time I get out of the car, pop the hood and hit the hoses with an IR gun, there's about a 35 degree temp difference between the upper and lower hoses and the temp is on its way down.

If it helps, idling in the driveway, and for several miles, the cluster temp gauge is just under half on the scale and the Autometer in the upper hose runs about 210. When I decide to pull over, the cluster gauge is at the top of the "safe" zone, and the Autometer at 235. This is frustrating!

mreid · 05-01-2017, 01:15 PM

This is embarrassing - the fans were indeed wired backwards. They blow air into the bay wired either way. I should have looked there first, just couldn't believe I would have made this mistake!

04-30-2017, 10:45 PM	#1
mreid Join Date: Jul 2015 Location: Loveland, CO Posts: 7 Trader Rating: (1) Feedback Score: 1 reviews	Another SR20det Overheating Problem I'm new to the SR, and hate to bring this up again because it's been hashed over so many times, but I'm stuck. Here are some of the details: SR20det notchtop - putting on break-in miles, but so far seems to run fine - except the overheating problem. New radiator, water pump, hoses, OEM thermostat, fans, etc. I've burped, and purged air multiple times based on several threads I've read and the FSM. I just don't think there is any air in the system. I'm not losing any coolant - no bubbles in the radiator - no white smoke. When the car is idling, everything seems fine. It warms up, I see coolant flow through the radiator, fans come on, the temp drops, and the cycle repeats. It never overheats while idling. After driving for several miles, it eventually will overheat. If I pull over and sit idling for 5 minutes, the temp drops down to where it should be - until I start driving again. Any suggestions would be much appreciated!!!

05-01-2017, 12:09 AM	#2
bfellini Zilvia Member Join Date: May 2005 Location: Eagle Rock, CA Posts: 167 Trader Rating: (6) Feedback Score: 6 reviews	Which ECT sensor (the single wire) is installed on the motor? Are both radiator hoses similar temp when you experience the issue? Be careful not to burn yourself when checking! Sent from my iPhone using Tapatalk

05-01-2017, 12:40 AM	#3
mreid Join Date: Jul 2015 Location: Loveland, CO Posts: 7 Trader Rating: (1) Feedback Score: 1 reviews	bfellini - The ECT is the older style spade lug, and I've replaced it. There is also an Autometer temp sensor in the upper hose. I don't know exactly what the difference in hose temp is when this happens. By the time I get out of the car, pop the hood and hit the hoses with an IR gun, there's about a 35 degree temp difference between the upper and lower hoses and the temp is on its way down. If it helps, idling in the driveway, and for several miles, the cluster temp gauge is just under half on the scale and the Autometer in the upper hose runs about 210. When I decide to pull over, the cluster gauge is at the top of the "safe" zone, and the Autometer at 235. This is frustrating!

05-01-2017, 01:15 PM	#4
mreid Join Date: Jul 2015 Location: Loveland, CO Posts: 7 Trader Rating: (1) Feedback Score: 1 reviews	This is embarrassing - the fans were indeed wired backwards. They blow air into the bay wired either way. I should have looked there first, just couldn't believe I would have made this mistake!