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Discussion Starter #1
Our '03 Murano has recently experienced a very high engine temp reading on the dash gauge. This has occurred while the outside temp has gone over 110 degrees. This is also the first season we have driven the car in this hot of weather.

Gauges can be misleading in that they don't indicate an actual temperature. By the same token, most people don't realize that an engine runs hotter than the boiling point due to the system being pressurized.

I would like to think that the outside temp is causing the rise in engine temp but one would think that the car was engineered to withstand outside temperatures in this range.

Once the outside temperature cools down, the gauge runs in the normal range.

When the car is shut off, I can hear coolant being emptied into the reservoir, so the coolant recovery system seems to be working.

I plan on having a pressure test done but was wondering if anyone else has experienced this and if they have any suggestions.
 

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Are you losing any coolant? Please define "high reading". Where on the gauge?
 

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Well, the idea of having the cooling system checked professionally is a good idea.
But I would wait until the car is cold and check to see that the radiator is completely full. People just don't check them anymore.
Then I would check to see if the overflow bottle was at the proper level.

Our 03 is getting fairly close to my usual massive coolant PM.
This is where I replace the coolant, the radiator cap, the thermostat, appropriate gaskets, and all hoses and belts.
I do this on all my cars after 3 years.

I had a thermostat that got stuck closed once. It caused the temp to rise at a great rate (I couldn't get the car off the freeway and turned off in time) and the head warped. The dealer wanted $1200 parts and $1200 labor on a car that was worth maybe $3000 at the time (1982).
Coincidentally, it was a Datsun. A 1977 Datsun 810 (First Maxima).
Since that time, I do a massive PM on every car. Never had another problem.



Homer
 

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Randy
Having a pressure test done is a good idea as this should answer any questions about the cap or a pin hole leak in the rad. I too would monitor the glycol coolant level to see if it is low or losing level on a daily basis. The other thing that you might want to check is the glycol mixture to see f it is too rich ( more glycol that the recommended 50/50 mix) as this too will cause your Mo to over heat .

But as you said in your note that the engine temp returns to normal when the day starts to cool down sounds like you are low on coolant.

Electronic temperature gauges and the like have and interesting failure indicator as the guage gets its signal from a temp transmitter, the transmitter usually either goes to full scale or to the bottom of he scale when they fail. Until that happens, it is usually working properly. Let us know what you find and good luck
 

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Why do car makers insist on putting "blank" gauges in a car? We should modify their corporate jets by replacing the altimeters with ones that have just two markings - HIGH and LOW. See how they like it.

That is one of my pet peeves against the MO. Just two simple "blank" gauges. My Jeep had 4 gauges (Fuel, water temp, oil pressure, ammeter) with appropriately marked faces. That is how all cars should be.

The MO's temp gauge does not even have minor tick marks to assist in determining a change a temp. Do the designers think that is artistic? Fashionable?

The cars of today are pretty damn smart, especially the MO. The data is available, why not display it properly?

Randy-
Sorry for my ramblings. Anyway, are you running the original coolant or has it been replaced? Coolant eventually degrades and needs replacement. Nissan recommends replacement after 60,000 miles.

How close to the upper-mark does the needle go?

-njjoe
 

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Discussion Starter #6
Thanks for the reply.

There does not seem to be any coolant loss. The gauge has a single mark below the "Hot" mark and it is running between this position and hot. It usually runs at the mid point on the gauge.
 

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Randy-

Be very, very careful running the engine at that temp. Overheating an aluminum engine will most likely warp the heads, and then the repair costs jump up a level or two.

Does the temp gauge read HOT when running at normal highway speeds in the 110 heat? If so, a radiator flush and coolant change may be called for.

Last summer I remember being impressed with the cooling capacity of the MO as I was sitting in stop-and-go traffic in 100 degree heat and the gauge barely moved at all. The guys in the southern areas of the US can better attest to the MO's cooling capacity.

-njjoe
 

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Discussion Starter #8
It went to hot once and then cooled back down to the upper mark. I was at highway speed (70 mph) when that happened. Dropping my speed down to 65 cools it down below the mark. It only seems to heat up on the freeway, but then that seems to be most of our driving as of late and during our heat wave.

In the old days, one remedy for cooling an engine down was to drop it down a gear and let the engine turn over a little faster to circulate the coolant but this does not seem to have any effect.

I am leary of getting the engine hot and I am concerned about the block being aluminum. I realize that it is hard to tell if it has gotten too hot before the damage is done but the car seems to be operating fine and it isn't hard to start after shutting it down.

I will get it into a shop and see if they can find anything.

Thanks to all who have posted.
 

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There is a service bulletin for the Murano radiator cap - the seal can degrade and this can affect the pressure in the system (i.e. fail to pressurize = overheating prone). I would check the cap with the engine cool, just to see if its ok.

Here is the link to the TSB.

Good luck.

http://www.nissanhelp.com/Ownership/Bulletins/Nissan/2004/NTB04-018.htm
 

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Could be the CVT running hot too (since the fluid is cooled in the radiator), but there should be an indication of that.
 

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Check the whole cooling system and replace everything that are needed. You DonWanna mess with it.

BTW, did you do alternator recall. They flush your coolant, just to let ya know~


NZM
 

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Nizmo said:
BTW, did you do alternator recall. They flush your coolant, just to let ya know~
Not always, there is an updated procedure that doesn't require that.

I don't think the CVT running hot could cause the temp gauge to rise. The CVT fluid is cooled by a smaller radiater next to the main one, not in the same one.

In short, it's a bad, bad thing to be driving around with the temp gauge that high, get it to a dealer or other technician.
 

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Randy,

Asside from the service bulletin mentioned earlier in this post, high temps are not normal nor do I recall others having issues like your.

Have the dealer check it. Please post findings if any your dealer uncovers.
 

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Tyler_Canada said:
The CVT fluid is cooled by a smaller radiater next to the main one, not in the same one.
The CVT fluid has a fluid-to-fluid heat exchanger that uses the radiator fluid as the coolant.

-njjoe
 

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njjoe said:


The CVT fluid has a fluid-to-fluid heat exchanger that uses the radiator fluid as the coolant.

-njjoe
Both correct. The CVT uses, like all automatic transmissions, a separate cooling tank right beneath the radiator (but separate from the engine coolant) and exchanges heat with the coolant through the metal interface between the two tanks. The rear of the CVT also has series of cooling fins making up a small fluid to air heat exchanger, and of course we all know the infamous metal/plastic scoop covering the tranny oil pan, which also has cooling fins.
 

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Does this mean when you do a cooling flush you should also ask for a CVT coolant flush at the same time?
 

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Gonzo said:
Does this mean when you do a cooling flush you should also ask for a CVT coolant flush at the same time?
The CVT doesn't have coolant - its transmission fluid circulating through those lines. But yes, you can drain the CVT fluid from those lines if you want (in fact thats the recommended method in the service manual).
 

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Eric-

The MO's CVT fluid is also cooled by a thermostatically-controlled, CVT-mounted water-to-oil (CVT fluid) heat exchanger. The radiator fluid is tapped off the heater core supply line.

-njjoe
 

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njjoe said:
Eric-

The MO's CVT fluid is also cooled by a thermostatically-controlled, CVT-mounted water-to-oil (CVT fluid) heat exchanger. The radiator fluid is tapped off the heater core supply line.

-njjoe
I posted that picture a while back, but didn't know the cooler valve assembly had its own temperature control. Maybe the name "cooler valve" should have been the giveaway (doh!). Very neat.
 
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