[phitchen333]

Hi, hoping you can help...
I have a 2009 Nissan Murano (3.5l petrol) - I'm seeing that the engine temperature gauge is going as far as the 3/4 mark whenever the engine is given some work (RPM goes over 2000 or any medium/long-distance driving). This started recently when I drove up to Byron Bay last week. No warning indicators are appearing on the dashboard (as yet!).
A new radiator, hoses and radiator cap were installed last October and whilst I was in Byron Bay a mobile mechanic replaced some hose clamps - there hasn't been a leakage of the coolant and the expansion-tank has remained a third-full and there isn't any liquid pooling underneath the car after overnight parking. The mechanic also said he didn't see an issue with the pump, belts or the radiator.
What I have seen is that the engine temperature gauge quickly rises to very hot when the aircon is on and the cabin temperature is set anywhere below 30 degrees...to get the engine temperature gauge back to halfway ('near' normal?) I have to set the cabin temp to maximum (32 degrees) and the fan on full.
What do you think?

 

[MuranoSL2003]

I would start by doublechecking the easiest/least expensive item, that newish radiator cap. Maybe it's not holding the pressure properly for some reason...

 

[PaulDay]

Sounds like the radiator system was not bleed properly and there are air pockets trapped in the system.

The tell is when you stated that the overflow container stays at a 1/3 full. Fluid level should be moving up and down as the engine heats and cools.

Too much air in the radiator system prevents a strong enough of a vacuum being created as the engine cools to pull fluid back into the system to keep it totally full.

On level ground, with the engine cold, mark the level in the overflow tank. When you're experiencing the overheating issue, pull over on a level spot and check the overflow tank level. The fluid level should be higher than the mark you made. If not, then you don't have enough fluid in the radiator system.

Anti-freeze should be flowing in and out of the overflow tank, which will maintain a full system without air pockets, preventing overheating issues from air being trapped in the engine.

The only guaranteed way to properly fill any Murano's radiator system to avoid air pockets is to use a "Radiator Funnel Fill Kit".

Cost is about $60 online.

Good luck.

Have a good day.

 

[chidog]

The only way air could be in the system is if a hose or bad pump seal, radiator, lets it in. In a 2004 I had no air problems and did not bleed it adding coolant after draining it (some cars/ engines have that problem and it shows up immediately at first run) . And being so long since the work was done etc. I highly doubt that is a problem, unless the hose or pump seal, radiator.
The things that come to mind is are the fans coming on for radiator? And coolant regulator or thermostat. Most important is when did this start happening? Maybe a hose is coming apart internally or the new radiator has some sort of blockage or restriction. It could even be a water-coolant pump impeller problem of some sort.
To satisfy the air lock theory, try what ever the experts suggest, keep us posted on what you find.
The radiator cap was a good suggestion.

 

[Pilgrim]

Hi, hoping you can help...

A new radiator, hoses and radiator cap were installed last October and whilst I was in Byron Bay a mobile mechanic replaced some hose clamps - there hasn't been a leakage of the coolant and the expansion-tank has remained a third-full and there isn't any liquid pooling underneath the car after overnight parking. The mechanic also said he didn't see an issue with the pump, belts or the radiator.

What about the thermostat? That's one of the frequent problem items.

 

[nitely]

Yes, stat, should have been replaced along with the radiator, upper and lower hoses. Fans, check your fans if its blowing on both low and high speeds--AC on.

 

[phitchen333]

Thanks -

I would start by doublechecking the easiest/least expensive item, that newish radiator cap. Maybe it's not holding the pressure properly for some reason...

Thanks for your response - the radiator cap is new and is keeping pressure (no indication of any leakage or 'steaming')

 

[phitchen333]

Sounds like the radiator system was not bleed properly and there are air pockets trapped in the system.

The tell is when you stated that the overflow container stays at a 1/3 full. Fluid level should be moving up and down as the engine heats and cools.

Too much air in the radiator system prevents a strong enough of a vacuum being created as the engine cools to pull fluid back into the system to keep it totally full.

On level ground, with the engine cold, mark the level in the overflow tank. When you're experiencing the overheating issue, pull over on a level spot and check the overflow tank level. The fluid level should be higher than the mark you made. If not, then you don't have enough fluid in the radiator system.

Anti-freeze should be flowing in and out of the overflow tank, which will maintain a full system without air pockets, preventing overheating issues from air being trapped in the engine.

The only guaranteed way to properly fill any Murano's radiator system to avoid air pockets is to use a "Radiator Funnel Fill Kit".

View attachment 55499

Cost is about $60 online.

Good luck.

Have a good day.

Thanks Paul.
The mobile mechanic used a "Radiator Funnel Fill Kit" (as you mention) to properly bleed the system and eliminate any air pockets. For the following two days, when the engine was cold and on a flat surface, I topped up the radiator (a quarter-cup of water on just one occasion). The overflow tank level is lower when the engine is cold.

I just can't see anything obvious form the engine cooling system (apart from perhaps the thermostat) so do you think the aircon system could be failing and overheating? (and consequently raising the temperature of the whole engine bay which reflects on the dashboard gauge)

 

[phitchen333]

The only way air could be in the system is if a hose or bad pump seal, radiator, lets it in. In a 2004 I had no air problems and did not bleed it adding coolant after draining it (some cars/ engines have that problem and it shows up immediately at first run) . And being so long since the work was done etc. I highly doubt that is a problem, unless the hose or pump seal, radiator.
The things that come to mind is are the fans coming on for radiator? And coolant regulator or thermostat. Most important is when did this start happening? Maybe a hose is coming apart internally or the new radiator has some sort of blockage or restriction. It could even be a water-coolant pump impeller problem of some sort.
To satisfy the air lock theory, try what ever the experts suggest, keep us posted on what you find.
The radiator cap was a good suggestion.

Thanks Chidog.
The fan is operating normally and there's no apparent leak from the radiator (no evidence on the garage floor at least!) - it starting happening last week at the latter part of a 600 km drive.
I was told by the mobile mechanic that it couldn't be the water-coolant pump as the engine would have simply ceased (and the car did manage to drive another 1000 km's to get me back home).

I've emailed a few local garages to see what they'd suggest...but no response as yet.

 

[phitchen333]

What about the thermostat? That's one of the frequent problem items.

Thanks Pilgrim...is there a way to test that at home or does that need a general or specialist mechanic?

 

[phitchen333]

Yes, stat, should have been replaced along with the radiator, upper and lower hoses. Fans, check your fans if its blowing on both low and high speeds--AC on.

Thanks Nitely.
I'll get the thermostat checked...the hoses were replaced.
When you say "check your fans if its blowing on both low and high speeds--AC on." what do you mean?...check the engine fans when the aircon is on?

 

[MuranoSL2003]

What about the thermostat? That's one of the frequent problem items.

Thanks Pilgrim...is there a way to test that at home or does that need a general or specialist mechanic?

Sure, remove the thermostat and place it in a pan of water with a thermometer. It should open fully at the temperature stamped on it.

 

[MuranoSL2003]

Thanks -

Thanks for your response - the radiator cap is new and is keeping pressure (no indication of any leakage or 'steaming')

The only way to know for sure it's performing to spec is to test it with a radiator cap tester.

 

[MuranoSL2003]

Sure, remove the thermostat and place it in a pan of water with a thermometer. It should open fully at the temperature stamped on it.

This is from my '03 service manual, I would imagine your 2nd gen has the same thermostat opening temperature:

 

[I need coffee]

If the thermostat is going to come out of the car then you might as well replace it since even an OEM part (Nissan 21200-JA10A) is inexpensive (less than $30 USD) and the gasket will need to be replaced regardless.

If you have access to a scan tool that can read live data then you can check to see if the thermostat is stuck in the closed position by monitoring the coolant temperature PID while the engine is warming up. Once temperature exceeds 180 F (82 C) the lower radiator hose should start to warm up noticeably as coolant starts to flow through it into the radiator. If temperature rises and the lower hose stays cool or only lukewarm to the touch then the thermostat is likely stuck closed. However, this test will not tell you if the thermostat is not opening all the way or otherwise not operating according to specifications.

You can test the cooling fan operation by running the IPDM Auto Active test (see below). If the fans are working properly, then it would seem that the likely culprit is the thermostat since you say the overheating condition only happens when the engine is under load (i.e. A/C turned on, climbing hills) and cooling system temperatures can be controlled by turning the heat on high--the heater core is basically an auxiliary radiator so this suggests to me that coolant isn't flowing through the radiator normally (...and you have a new radiator and hoses).

 

[PaulDay]

Check to see if an OEM thermostat was used. An aftermarket thermostat might not have the same open flow rate as the OEM one, causing a heating issue under load when the engine will be running hotter.

Just an idea to check first and easiest.

If you're losing fluid and not seeing any obvious spots under the car when parked, then you should start to look for an internal issue. Like a compromised head gasket, weeping antifreeze into the combustion chamber.

After the engine is to temp, smell the exhaust as someone steps on the gas, to about 1500 RPM several times in a row. Does it have a very slight sweet smell, or seem to have excessive moisture coming out?

Have the radiator fluid checked for exhaust gases.

Good luck.

Have a good day.

 

[chidog]

The only way air could be in the system is if a hose or bad pump seal, radiator, lets it in. In a 2004 I had no air problems and did not bleed it adding coolant after draining it (some cars/ engines have that problem and it shows up immediately at first run) . And being so long since the work was done etc. I highly doubt that is a problem, unless the hose or pump seal, radiator.
The things that come to mind is are the fans coming on for radiator? And coolant regulator or thermostat. Most important is when did this start happening? Maybe a hose is coming apart internally or the new radiator has some sort of blockage or restriction. It could even be a water-coolant pump impeller problem of some sort.
To satisfy the air lock theory, try what ever the experts suggest, keep us posted on what you find.
The radiator cap was a good suggestion.

Just like Sylvester Stallone in that movie, Chidog drew first blood on the "thermostat".
As far water pump seal that was a sarcastic statement because it would pollute the engine oil. But I have seen water pump impellers destroyed or come off the shaft (slip on the shaft), then it won't pump. And yes the engine would still run, since the shaft is still intact. Yes not very likely to happen but, it still belongs on the list.
I agree with if your removing the thermostat, get a new one check it like mentioned in the post. Yes also check the one removed to see if it was for sure the problem.
We now know its not an air lock, since it ran for quite awhile with no problem. Right?

 

[Pilgrim]

For that matter, if you want to be thorough, check a NEW thermostat before installing it.

Changes are 95% that it will be OK, but it's enough work that you might want to avoid the potential 5%.

 

[nitely]

Thanks Nitely.
I'll get the thermostat checked...the hoses were replaced.
When you say "check your fans if its blowing on both low and high speeds--AC on." what do you mean?...check the engine fans when the aircon is on?

Your radiator fan (driver side), and condenser fan (passenger side) should blow high whenever you turn on your AC. With AC off on cold engine, the radiator fan will start blowing low then high after idling for approx. 15 minutes-depending on ambient temp.

Old thermostat normally slows down the opening and closing to the point of not moving anymore. You compare your new stat with the old stat on boiling water and you will see the difference.

 

[chidog]

Just like Sylvester Stallone in that movie, Chidog drew first blood on the "thermostat".
As far water pump seal that was a sarcastic statement because it would pollute the engine oil. But I have seen water pump impellers destroyed or come off the shaft (slip on the shaft), then it won't pump. And yes the engine would still run, since the shaft is still intact. Yes not very likely to happen but, it still belongs on the list.
I agree with if your removing the thermostat, get a new one check it like mentioned in the post. Yes also check the one removed to see if it was for sure the problem.
We now know its not an air lock, since it ran for quite awhile with no problem. Right?

Again chidog drew first blood on Checking the new thermostat.