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Overheating runs hot

Old 09-04-2015, 09:05 AM
  #1  
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Overheating runs hot

Ok I took a cpl hours and read up on this here and I don't think anyone has my issue exactly. Theer are def some similar stories. Here we go:


98 max, 190k, 5 speed. I have been taking care of the car but now she's running hot. The needle was just below halfway for quite some time - right where it should be.


If I drive with the AC on and hit the highway the needle will go up to about 75% after a few miles. If I drive around town with AC on it still gets up there but it takes a little longer.


If I drive with the heat on the needle will drop especially if I'm driving around town. Sometimes the needle will drop to about 35% - below where the needle used to sit which was just below halfway.


If I let her idle it doesn't matter if I turn the heat or AC on.. the needle will not move up. Maybe it would move up if I blasted the AC and let her idel for a long period of time but my point is the needle becomes more erratic when I'm placing a load on the car.


Things to note:


* Heat works well
* AC works well
* Both rad fans come on
* Replaced water pump 9 months ago
* Replaced Rad cap 9 months ago (OEM)
* Replaced Thermostat 9 months ago (OEM)
* Rep[laced radiator 2 1/2 years ago
* No leaks anywhere
* Coolant/fluid is in the reserve tank just sitting quietly.
* I took rad cap off, parked on incline, blasted heat, burped car for close to a half hour. When I hit the gas and revved the engine to 2k - 3k rpms some coolant would spill out (normal I assume.) I did not have a no spill funnel. I topped off fluid afterwards.
* Bath Radiator hoses are very hot to the touch when running.
* Car runs & idles well.


I'm playing a cat and mouse game right now cause it's hot out and I want to use the AC but I have to not only shut off the AC but blast the heat to get the needle to move down. The needle has not made it to the 1st warning mark (about 85%) but the needle is getting close and I don't want to drive too far to find out. Yesterday I made two 20 mile trips - to & from work. I made it up & back but I feel like if I take my eye off the temp gauge for a few minutes the needle may move to the danger zone and then I may have bigger issues.


I had a 96 Max for 14 years and my 98 max for the past 3 years. I'm no mechanic but I got to know the car fairly well over the years.


Sorry for long rant.


Thoughts?

Last edited by captchaos; 09-04-2015 at 09:10 AM.
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Old 09-04-2015, 09:54 AM
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Is it actually running hot? I had a similar problem on my Camry. It was the temperature gauge sending unit. It looks like the only thing you haven't replaced is that and the engine coolant temp sensor.(ETCS)
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Old 09-04-2015, 09:59 AM
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Originally Posted by captchaos View Post
Ok I took a cpl hours and read up on this here and I don't think anyone has my issue exactly. Theer are def some similar stories. Here we go:


98 max, 190k, 5 speed. I have been taking care of the car but now she's running hot. The needle was just below halfway for quite some time - right where it should be.


If I drive with the AC on and hit the highway the needle will go up to about 75% after a few miles. If I drive around town with AC on it still gets up there but it takes a little longer.


If I drive with the heat on the needle will drop especially if I'm driving around town. Sometimes the needle will drop to about 35% - below where the needle used to sit which was just below halfway.


If I let her idle it doesn't matter if I turn the heat or AC on.. the needle will not move up. Maybe it would move up if I blasted the AC and let her idel for a long period of time but my point is the needle becomes more erratic when I'm placing a load on the car.


Things to note:


* Heat works well
* AC works well
* Both rad fans come on
* Replaced water pump 9 months ago
* Replaced Rad cap 9 months ago (OEM)
* Replaced Thermostat 9 months ago (OEM)
* Rep[laced radiator 2 1/2 years ago
* No leaks anywhere
* Coolant/fluid is in the reserve tank just sitting quietly.
* I took rad cap off, parked on incline, blasted heat, burped car for close to a half hour. When I hit the gas and revved the engine to 2k - 3k rpms some coolant would spill out (normal I assume.) I did not have a no spill funnel. I topped off fluid afterwards.
* Bath Radiator hoses are very hot to the touch when running.
* Car runs & idles well.


I'm playing a cat and mouse game right now cause it's hot out and I want to use the AC but I have to not only shut off the AC but blast the heat to get the needle to move down. The needle has not made it to the 1st warning mark (about 85%) but the needle is getting close and I don't want to drive too far to find out. Yesterday I made two 20 mile trips - to & from work. I made it up & back but I feel like if I take my eye off the temp gauge for a few minutes the needle may move to the danger zone and then I may have bigger issues.


I had a 96 Max for 14 years and my 98 max for the past 3 years. I'm no mechanic but I got to know the car fairly well over the years.


Sorry for long rant.


Thoughts?
Do fans come on with a/c off? Our cars have a two speed fan setup...also when u turn heat on was it on defrost? That will also make a/c compressor run and trigger the low speed side of the fans..check to make sure both speeds are working...if the high speed side isn't working check your relays in front of the battery
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Old 09-04-2015, 10:04 AM
  #4  
JvG
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Your problem sounds like a thermostat that is going out.

Sometimes we rack our brains thinking of causes. We tend to assume that the parts we have replaced cannot possibly be broken again.

I have encountered bad newish thermostats. I also replaced every cooling parts in a water-cooled Porsche I had once. Same symptoms as yours. Drove me nuts. Replacing the thermostat solved the problem.

Moral of this this story.... do not assume that a part which you just replaced is always good.



Back in the days of points and condensors in distributers
we would sometimes get bad condensors, right out of the box.
The car would not start at all. But I did everything right, all the parts were new..... reinstalled the old condensor, car ran very well.
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Old 09-04-2015, 10:39 AM
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It could be the t-stat, but before you go throwing parts at it, check the sensor. It's the single wire unit, make sure the connection is clean.
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Old 09-04-2015, 04:01 PM
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Originally Posted by jerrod99_se-l View Post
Do fans come on with a/c off? Our cars have a two speed fan setup...also when u turn heat on was it on defrost? That will also make a/c compressor run and trigger the low speed side of the fans..check to make sure both speeds are working...if the high speed side isn't working check your relays in front of the battery

Yes the fans will come on when the heat is on and the temp gets like half way. I had heat blowing thru vents not defrost. The fans appear to be working fine. I don't know much about the 2 speeds.
What do you mean check your relays in front of the battery???
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Old 09-04-2015, 04:02 PM
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Originally Posted by njmaxseltd View Post
It could be the t-stat, but before you go throwing parts at it, check the sensor. It's the single wire unit, make sure the connection is clean.

I unplugged the ETCS and looked at it. It looked fine to me but I also don't know what a bad 1 would look like. I plugged it back in.
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Old 09-04-2015, 04:46 PM
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Originally Posted by JvG View Post
Your problem sounds like a thermostat that is going out.

Sometimes we rack our brains thinking of causes. We tend to assume that the parts we have replaced cannot possibly be broken again.

I have encountered bad newish thermostats. I also replaced every cooling parts in a water-cooled Porsche I had once. Same symptoms as yours. Drove me nuts. Replacing the thermostat solved the problem.

Moral of this this story.... do not assume that a part which you just replaced is always good.

Back in the days of points and condensors in distributers
we would sometimes get bad condensors, right out of the box.
The car would not start at all. But I did everything right, all the parts were new..... reinstalled the old condensor, car ran very well.

Understood. Wouldn't the hose be cool to the touch when the car is warmed up though if it was a bad T-Stat?
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Old 09-04-2015, 05:50 PM
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As a general rule of thumb, if a car overheats in town, but not on the highway, it's the radiator fan. If it overheats on the highway, but not in town, it's either the thermostat or water pump. I've seen bad water pumps that worked OK at low speed, but didn't pump much at higher sustained speeds. I have also seen water pumps that changed rotational direction from year to year--put in one from the wrong year and the impeller is turning backwards! Also noted that you said you recently replaced the water pump, but not with an OEM part.
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Old 09-05-2015, 12:44 AM
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Originally Posted by captchaos View Post
Yes the fans will come on when the heat is on and the temp gets like half way. I had heat blowing thru vents not defrost. The fans appear to be working fine. I don't know much about the 2 speeds.
What do you mean check your relays in front of the battery???
The radiator cooling fans have 2 speeds as stated. How the fans work depends on whether you are using the a/c or not and is also coupled with the vehicle speed.

Without the a/c on, the cooling fans will start running on low speed when the coolant reaches 203 F. If the coolant temperature increases to either 212 F or 221 F (depends on the speed of the car), the fans will run at high speed.

With the a/c on, the temperature numbers are different. When you turn on the a/c, the fans run at low speed right away to cool the a/c refrigerant that gets heated up by the a/c compressor. When the engine coolant temperature reaches 203 F, the fans will start running at high speed.

Check the fuses for the radiator fans. The low speed and high speed have separate fuses. The fuses are in the fuse block between the battery and the fender. RAD FAN 1 fuse is for the low speed and RAD FAN 2 is for the high speed.

One thing I would like you to do is monitor the temperature of the engine coolant. And I don't mean by looking at the dash gauge. Get an OBD code reader that can display live data, not just the check engine codes. I'm curious to find out if the engine is overheating or if the temperature gauge sending unit is flakey.
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Old 09-05-2015, 10:24 AM
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Originally Posted by DennisMik View Post
The radiator cooling fans have 2 speeds as stated. How the fans work depends on whether you are using the a/c or not and is also coupled with the vehicle speed.

Without the a/c on, the cooling fans will start running on low speed when the coolant reaches 203 F. If the coolant temperature increases to either 212 F or 221 F (depends on the speed of the car), the fans will run at high speed.

With the a/c on, the temperature numbers are different. When you turn on the a/c, the fans run at low speed right away to cool the a/c refrigerant that gets heated up by the a/c compressor. When the engine coolant temperature reaches 203 F, the fans will start running at high speed.

Check the fuses for the radiator fans. The low speed and high speed have separate fuses. The fuses are in the fuse block between the battery and the fender. RAD FAN 1 fuse is for the low speed and RAD FAN 2 is for the high speed.

One thing I would like you to do is monitor the temperature of the engine coolant. And I don't mean by looking at the dash gauge. Get an OBD code reader that can display live data, not just the check engine codes. I'm curious to find out if the engine is overheating or if the temperature gauge sending unit is flakey.

I haven't had a CEL in several months after I replaced an O2 sensor.


The fans are working at both speeds. I can hear them and see them.


Plus the temp goes up when the AC is on and comes back down when heat is on (both AC/heat work fine.) See original post.


I think the car (when it runs hot and the needle is close to the top) is ready to overheat if the needle goes up a bit more. I can feel the car get a tad weaker.
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Old 09-05-2015, 03:13 PM
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We still need to know what the actual water/coolant temperature is.... not what the gauge shows.
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Old 09-06-2015, 12:01 PM
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''One thing I would like you to do is monitor the temperature of the engine coolant. And I don't mean by looking at the dash gauge. Get an OBD code reader that can display live data, not just the check engine codes. I'm curious to find out if the engine is overheating or if the temperature gauge sending unit is flakey.''


I tried to look up what you asked but I'm a little lost.
In simple terms please explain what you mean. Pretend I'm 10 years old. Seriously.
Do I drive the car while doing this? At idle the needle stays just under half way and does not move (seems perfect.) I've let her run at idle for almost a half hour while blasting the AC and revving the engine and the needle stays fine and the car is not overheating.


Today I made a 5 mile trip (stop and go) up and 5 miles back (brief stop in between.) It's nice out so I left AC off. The needle was fine (just below half way.)

Last edited by captchaos; 09-06-2015 at 12:07 PM.
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Old 09-06-2015, 02:29 PM
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What I am trying to find out is the engine actually overheating or is the temperature gauge in the dashboard instrument cluster not correctly showing the temperature of the engine coolant.

So to do this, you will have to hook up some kind of test equipment to the car that can show you the temperature of the coolant inside the engine. An OBD code reader can do this. Some people may call this a code scanner. This is what mechanics use to see why your check engine light is on.

But not all code readers can display the engine coolant temperature. The cheap ones for $25 or less usually can't, they only show the check engine light code.

But you get a code reader that can show information while the engine is running (i.e., live data), connect it to the OBD port located by the fuse panel and start driving the car. Watch the engine coolant temperature while you are driving. When you see that the temperature gauge in the dash is starting to rise above the normal spot, look at the OBD code reader and see what the engine coolant temperature is.

On a car that is working OK, you will see that the temperature of the engine coolant gets up to between 200 and 205 F and then it will drop down to around 185 F. What has happened is that the radiator cooling fans have turned on. This up and down temperature thing will keep repeating over and over. If you are driving on the highway with the a/c on, you may see the temperature go up to as high as 220 F before it starts to come down.

So If you don't own an OBD code reader, see if you can borrow one from somebody. Auto parts stores rent tools, maybe they will rent a code reader. With all the things you have done to your car, it seems strange that it is overheating. Maybe it is, but maybe the temperature gauge in the dash is bad or the sending unit for the gauge is bad. This will tell you.

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Old 09-08-2015, 08:05 AM
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Your coolant. Straight coolant or 50% mix? Green stuff?
Also, as has been suggested, maybe the NON OEM water pump dosn't quite cut it.
Everything else you've done is excellent maintenance for the cooling system.
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Old 03-14-2016, 11:12 AM
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Ok I found the solution. I was running the car all winter with the heat on and I didn't have any issues cause when the heat is on the needle stays just below half way (see OP.) It was hot 1 day last week so I turned the heat off. The needle started creeping up again just like it did months ago.


I took the car to my mechanic friend (he replaced my water pump and thermostat.) He looks it over and says "you're radiator is bad. I can see tiny bubbles at the top of the radiator where the metal meets the plastic."


Now I took the radiator out months ago and checked for clogs/leaks and everything seemed fine.


I still wasn't 100% sold on the problem/solution since the radiator (radiator barn) was only 3 years old and had 30k miles on it.) I replaced it and drove the car for a week with heat off. The needle is perfect.


Looks like I just had a bad radiator that was not holding pressure.


Just thought I would share.
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Old 03-14-2016, 12:14 PM
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Some replacement radiators last longer than others.

Since yours did not last long, please tell us which brand of radiator failed.

You might help other members so that they know which brand NOT to buy.

Glad you fixed your problem.
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Old 03-15-2016, 12:18 PM
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I bought the Radiator from "Radiator Barn" but I don't know what brand it was. I recall trying to get the cheapest radiator since I thought it would last at least several years. I believe Radiator Barn got bought out by another company. Sorry I could not give more info.
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