Hi

I just replaced the radiator on my sisters car with a 3.0 and now the temperature gauge isn't working and the lower radiator hose doesn't get hot, the upper hose gets hot. The thermostat was replaced less then a year ago, but when I squeeze the lower hose I can hear a clicking sound coming from inside of the thermostat housing as if something is being pushed back and forth. I'm going back to her place on Saturday and I'm hoping to get a couple of ideas on what to check out to fix the problem.

 

Air is probably trapped in the system. You need to raise the front of the car over 1 foot. Remove the radiator cap. Run the car until it's good and warm.
blip the throttle occasionally to get the air out. The process should take about 20 min or more.

 

Hi

Thanks I'll give that a try, could that also prevent the temperature gauge from working?

 

Of course.

the temperature sensor in the engine is meant to touch coolant. It's touching air for now.
It will read correctly once you bleed the air from the engine.

 

Hi

It turns out the sensor for the gauge has gone bad, also is it normal for the lower radiator hose to get hot then cold then hot then cold constantly? The thermostat opens 16th of an inch at exactly 180 degrees, one degree lower and it closes completely. I would have thought it would open at least an 8th of an inch, and close a little slower then it does.

 

All symptoms of not enough coolant because air is in there instead.

Bleed the air out of it like I told you.

 

Hi

I did do that, it took 20 to 30 minutes to get all the air out, Then a CEL code popped up and said faulty temp sensor.

 

There are a few videos on YouTube showing how to test and replace the coolant temperature sensor. Also check the harness connector to the temp sensor for broken wires.

 

Yeah I've had two instrument cluster and each one of them had faulty water temp gauges...Not sure if I can find out why they fail so often?

 

Hi

I'll fix that the next time I'm at my sisters place. But I am having a hard time trying to figure out why the thermostat acts the way it does on this engine. When the thermostat gets to 180 degrees it opens up, but the moment the colder coolant comes into contact with the thermal springs on the thermostat it closes almost instantly. It's just weird, I mean I can reach down and touch the lower half of the radiator and it is cool to the touch. And before anyone says I need to bleed the system, I did do that and was able to get an extra half a gallon of coolant into the system.

Is the thermostat supposed to close almost instantly after the colder coolant starts flowing or is it supposed to stay open?

I'm just used to seeing the thermostat on the outlet side of the engine, not the inlet side.

 

The purpose of a thermostat is to keep the engine at a minimum operating temperature, 180ş F (82ş C). The purpose of the radiator, water pump and engine temperature sensor (ECTS) is to keep the engine from exceeding the ideal operating temperature, approx 203ş F (95ş C).

The thermostat has a small, mysterious piece built into the rim of the thermostat that usually is ball shaped. This little "thing" is not tight and is called the "jiggle valve". Its purpose is to allow a small amount of coolant to pass through the thermostat when the valve is closed. Since this piece is loose, this could be the sound you are hearing when you squeeze the radiator hose.

The specifications for the Nissan thermostat is the the main valve should open (lift up) more than 8.6 mm (.339 inch) at 203ş F (95ş C). There is no info about what happens at 180ş F (82ş C), which is the opening temperature. What the specifications do say is that the valve should close at 9ş F (5ş C) BELOW the specified opening temperature of 180ş F (82ş C). This last part implies that your thermostat is not operating normally. But how are you determining hot and cold?

The thing that causes the thermostat to open is not the spring. There is a small cylinder shaped piece, maybe 1 cm in diameter, that is filled with some kind of chemical paste that expands and contracts with temperature changes. This is what makes the thermostat open. The spring is to close the valve.

The part I can't figure out is that you do not have coolant circulating through the radiator. I base this on you saying that the lower radiator hose does not get hot. If there is no coolant circulating, then the engine will overheat. But you have not said the engine is overheating.

It sounds like you are getting some parts since you are not getting the temperature gauge to work. So I will wait for you to let us know how that worked out.

I hope that you have found out that there are 2 temperature sensors in the engine. One is for the gauge in the dash and the other is for the car's computer (ECU). The 2 sensors are side by side, located right after the coolant exits the engine block and before the radiator hose. The sensor with just one wire is for the temperature gauge in the dash and the one with 2 wires (the ECTS) is for the car's computer.

 

Hi

It turns out the temperature gauge sensor was bad, and to make sure the new one was working right I had my obd2 scanner hooked up so I could see the exact temperature as the engine wormed up. The temp stayed around 200 degrees once the engine wormed up, I still need to drive the car to make sure it doesn't over heat while being driven, but the has to wait until after my sister cleans up all the mold from inside the car. As for the lower radiator hose it's still cold to the touch, I'll more then likely replace the thermostat if the lower hose is still cold to the touch after I take it for a drive.

"But how are you determining hot and cold?" I tested the thermostat out in a pot of boiling water and used a glass sugar thermometer to monitor the temperature of the water, at exactly 180 degrees it opened about a 1/16 of an inch but didn't open any wider, even when the water reached 200 degrees. Other thermostats that I have tested this way have always opened up at least a 1/8" to 1/4".

 

I'm going to guess that you replaced the radiator because the car was over heating?

A thermostat which barely opens will result in overheating.

it also results in a cool radiator because the hot water does not pass through the thermostat.

id say that you should replace the thermostat.

Our cars seen to do best with oem Nissan ones.

I'm going to guess that the themostat you relic ed a year ago was not an oem Nissan, but an after market brand such as Stant?

 

Hi

The radiator was literally coming apart at the seems, so it had to be replaced.
My sister had someone else replace the thermostat with a aftermarket, but I did have to fix that persons mistakes.
The oem Nissan thermostat is what I was planing on getting.

 

The oem thermostat should end your problems.

Please let us know about the outcome.

 

This thread is confusing. The ECU and gauge use 2 different temp sensors. They are right next to each other. ECU uses the 2 wire. Gauge and HVAC use the 1 wire.

 

Hi

I'm not understanding what your trying to say about the two sensors.

 

JSutter is repeating what I said but worded differently.

Since you have driven the car using an OBD scanner to monitor the engine coolant temperature, the 200ş F that you got is where it should be. I have monitored my car this way in 110ş F temps while in stop & go rush hour traffic and it only varied by a degree or two. I'm thinking that your concern about the lower radiator hose being cold is probably from your unfamiliarity with the Maxima since you have driven the car without it overheating.

But the thermostat opening only an eight of an inch is less than a third of the factory spec of .339 (an eighth of an inch is .125 - three eights of an inch is .375). If you live in a warm climate like me, I would strongly advise you replace the thermostat with one from Nissan, after market thermostats seem to cause problems. There are many, many threads on this.

 

Hi

I'll be picking up a new thermostat from Nissan on Saturday.

 

Hi

The new oem thermostat fixed the problem, now if I could only get the air bag light to stop blinking.

 

Glad to read that.

Regarding the air bag light.

1. Is there a State inspection for that kind of thing.

2. If not, would you like to remove that light bulb?

 

Before you decide to remove the bulb, try this simple reset procedure that I found in an older thread. I’ve also read that if your Maxima has side air bags, the air bag light can sometimes be triggered by the wires being pinched under the driver/passenger seat. Make sure the wires under the seat are free and remove any clutter under there.

 

The water temperature gauge is connected to the water temp sending unit (temp bulb) the water temperature sensor is connected to the ECU....The purpose of the water temp sensor is to notifiy the ECU of your cold start situation (open loop) in the morning, once up to temp (closed loop) and when to turn the cooling fans are triggered to turn on.

 

Hi

I used to be able to reset the air bag light but it won't reset anymore. I checked under the passenger seat but couldn't find any pinched wires. The car was in a side impact collision, resulting in the rear passenger side fender being crushed in.