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Discussion Starter · #1 ·
Hey all,

Well I love my truck, but it's been giving me headaches recently. I've got an overheating issue that I can't figure out.

Back in November last yr it was getting too hot when I drove at highway speeds. The gauge went up to about 1/8th-3/16th inches to the 'too hot' line, so I replaced the thermostat, but that didn't fix the problem. I figured I'd need to do the water pump, but was busy and it was getting winter so I let it go. When it did get too hot, I'd blast the heat and the temp gauge quickly fell to a more acceptable level.

So I went to install a new water pump, which is a much bigger job than the thermostat, but got it done. My old water pump looked brand new though, rotated fine, had all its fins, so I doubted it was the problem. While everything was still apart, I figured I'd get a radiator too, since it was 13 yrs old and maybe it got clogged.

But it's still not fixed! New thermostat, water pump and radiator and it STILL gets too hot! Both fans seemed OK when it was dismantled (spun OK, no bad bearings) and I checked that both fans are spinning when the engine starts except that I can't check the electric fan when the problem happens at 65 mph. At idle it won't get too hot, it's only at highway speed after about 10 minutes.

Any ideas what else I need to do??

As an aside, which somehow could be related, when I got the truck in '09, anytime I was stopped at a light, the heat air would turn cold. As long as I was moving the heater was perfectly fine, but as soon as I stopped the air would get cold. This is another reason I first replaced the thermostat, as maybe it was slightly bad for all those yrs? After I replaced the thermostat in Novemeber, this issue went away. Maybe the temp gauge is wrong, but since it responds correctly when I turn the heat on, I wouldn't think so.

Thanks for any help...

CJ
 

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Did you burp all the air out of the cooling system? That’s the cause of low or no heat at idle.
Also the plain flat cap goes on the radiator and the spring loaded cap goes on the plastic overflow bottle.

Clint
 

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Did you burp all the air out of the cooling system? That’s the cause of low or no heat at idle.
Also the plain flat cap goes on the radiator and the spring loaded cap goes on the plastic overflow bottle.

Clint
^^ All of these. And did you use an OE or aftermarket TStat? The Nissan's seem to be real particular about genuine parts.
 

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Discussion Starter · #4 ·
Clint - I checked the fluid of course, but never did any extra 'burping.' Is there a bleeder vale or something? When I replaced the Tstat I checked and added fluid for a few days thinking eventually the air bubbles would reach the radiator or the reservoir tank. The original caps have different size indents, so you can't put them on the wrong one. And I know that because...

Didn't use Nissan Tstat for replacement. It was an Autozone or Advance one.
 

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^^ All of these. And did you use an OE or aftermarket TStat? The Nissan's seem to be real particular about genuine parts.
One more thing, the little jiggler on the thermostat base goes on top as it allows air to pass through easier.

Clint
 

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Temp gauge sensor? Nissan uses 2 coolant temp sensors. One for the gauge the other for the ECU.

Are you steaming or over flowing the reservoir. Next would be a bad radiator or blocked passage.

I often "gut" a thermostat when troubleshooting a cooling problem just to rule it out. Can't recall if the T-stat on these trucks need the outter rim to seal. But I have cut the guts out of a t-stat to make sure it flows.
 

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It seems to me that you either have a bad temperature sensor or the coolant flow is not going through the radiator in a good way. When you turn on the in-cabin heat, the heater core removes the heat. As you have seen coolant temps go down when you engage the heater core, this obviates a bad sensor.

Get or borrow an IR temperature reader. They are handy devices and are surprisingly cheap. When the truck over heats, quickly pop the hood and measure the temperature at the top of the radiator and bottom of the radiator. There should be a healthy temperature drop, say 10 °F. If the drop is poor, it indicates a bad radiator. But you have a new radiator so the measurement is an inference of coolant flow. A large temperature drop, say 30 ° F indicates a large residence time of the coolant in the radiator. This means the coolant flow is impaired in some way.

A bad T-Stat is the prime culprit for bad flow. Collapsed hoses are another. Plugged coolant passages in the engine is a third possibility.
 

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A bad temperature sensor wouldn't just malfunction during highway driving.

My guesses:

1. Air bubble in the cooling system, or
2. Head gasket leak.

Incidentally, don't feel bad about having replaced those parts. At that age, they could have failed pretty soon anyway.

Typically, it's the seals and bearings that fail first in the water pump - not the impeller. You get grinding noises, and coolant leaks.
 

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Yr of truck and miles is always good info to include w/ reported problems. Getting your truck in '09 means it could be a Gen 1 '98 or earlier for all we know. Just saying.

Nissan thermostat. Burp system. Coolant sensor check/replacement. Then if problem persists, it might be time for a deeper look into the cooling system's function: rad, water pump, head gasket, etc...
 

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Yr of truck and miles is always good info to include w/ reported problems. Getting your truck in '09 means it could be a Gen 1 '98 or earlier for all we know. Just saying.
Nah !!!! We're good guessers !!!

Without enough real information supplied, I just say
333582


And no soup either.
 

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Discussion Starter · #12 ·
Hey guys... sorry bout the lack of info. I put the 2007 SE CrewCab Longbed in my profile but I see that doesnt show on posts. 145k miles

The ‘overheating’ I see is just the temp gauge going higher than it ever did. Again this morning it got within 1/8th” of the high line (going uphill) when for 12 yrs it was below half on the gauge.

I have a temperature ’gun’ and got to check it right after it cooled down after it was too hot and I found 165 on top radiator hose and 95 on bottom hose. The reservoir tank was also 165. So that indicates bad flow so the (new) aftermarket Tstat is a likely problem? Oil always looks good so I don’t see a head gasket leak nor is there a coolant leak when parked.

If I still have air in the system where’s the ideal place to burp it?

And yeah, replacing extra parts isnt the worst thing, I don’t plan on getting rid of it for a while!

Thx
 

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Hey guys... sorry bout the lack of info. I put the 2007 SE CrewCab Longbed in my profile but I see that doesnt show on posts. 145k miles

The ‘overheating’ I see is just the temp gauge going higher than it ever did. Again this morning it got within 1/8th” of the high line (going uphill) when for 12 yrs it was below half on the gauge.

I have a temperature ’gun’ and got to check it right after it cooled down after it was too hot and I found 165 on top radiator hose and 95 on bottom hose. The reservoir tank was also 165. So that indicates bad flow so the (new) aftermarket Tstat is a likely problem? Oil always looks good so I don’t see a head gasket leak nor is there a coolant leak when parked.

If I still have air in the system where’s the ideal place to burp it?

And yeah, replacing extra parts isnt the worst thing, I don’t plan on getting rid of it for a while!

Thx
A delta T of 70 ° F from top to bottom of the radiator means the coolant flow is very weak. In fact very weak. Even with no water pump, the thermosiphon effect would cool the engine better than this.

Before you threw part at the problem, there was no hint of a bad water pump or T-STAT. Also, the coolant system does not create an air pocket by itself. It usually occurs during a coolant change.

Your greatest fear is a blocked water jacket in the engine. Unless you used a radiator sealer, the most likely cause is a blown head gasket.

Replace the T-Stat with a blank. Something to demonstrate that it is not causing the block.
 

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With all the work done, make sure you have the caps on correctly. People who think they know better will put them on wrong. The cap that is nothing more than a rubber seal, goes on the radiator. The one with the spring, that goes on the bottle. Get them wrong, you will have cooling issues that include not being able to get the air out of the cooling system.

As for getting the air out, top off the bottle to at least the max mark, if not more, go drive it. Check and repeat until it stays at max. Any time you remove the radiator cap you have to start over. Do not remove the radiator cap to add coolant. Only remove the radiator cap to fill a completely empty system. Use the bottle top finish the job.
 

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Remove the oil fill cap, look at the inside of the cap. If you have a blown head gasket you may see a milky slim from coolant in the oil.
 

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I 2nd very easily the caps pressure on bottle plus Ill add a fan clutch to mix


reason for edit spelt easily wrong
 

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A delta T of 70 ° F from top to bottom of the radiator means the coolant flow is very weak. In fact very weak. Even with no water pump, the thermosiphon effect would cool the engine better than this.

Before you threw part at the problem, there was no hint of a bad water pump or T-STAT. Also, the coolant system does not create an air pocket by itself. It usually occurs during a coolant change.

Your greatest fear is a blocked water jacket in the engine. Unless you used a radiator sealer, the most likely cause is a blown head gasket.

Replace the T-Stat with a blank. Something to demonstrate that it is not causing the block.
I'd second this. I have had more than one bad new parts store thermostat over the years. Easy and cheap enough to swap/check....
 

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As @Sabretooth mentioned...fan clutch could be worn out.
IMHO, worn out fan clutch would overheat at idle, not while moving.
My money goes on two items, OEM TStat replacement and serious burping of the cooling system, sounds like a large trapped air pocket.
 

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Hey guys... sorry bout the lack of info. I put the 2007 SE CrewCab Longbed in my profile but I see that doesnt show on posts. 145k miles

The ‘overheating’ I see is just the temp gauge going higher than it ever did. Again this morning it got within 1/8th” of the high line (going uphill) when for 12 yrs it was below half on the gauge.

I have a temperature ’gun’ and got to check it right after it cooled down after it was too hot and I found 165 on top radiator hose and 95 on bottom hose. The reservoir tank was also 165. So that indicates bad flow so the (new) aftermarket Tstat is a likely problem? Oil always looks good so I don’t see a head gasket leak nor is there a coolant leak when parked.

If I still have air in the system where’s the ideal place to burp it?

And yeah, replacing extra parts isnt the worst thing, I don’t plan on getting rid of it for a while!

Thx
If your Frontier is between 2005 and 2010, get your radiator replaced. If your coolant gets old, it gets acidic and can create little pinholes in the bulkhead welds between the radiator and the transmission oil cooler. This was a formula for disaster either from coolant leaking into the trans cooler or little bits clogging the cooling fins of the radiator.

The dealer fix was to bypass the trans cooler, but you have the potential to have cooling problems. A 2011-plus or even an aftermarket radiator is a good idea (my son put a nice aluminum one in my old 2002 SC Desert runner after he took it from me). I kept on top of the coolant in my 2010 and found out about the recall when I had 200,000 miles on it. It was in the dealer for another service and they told me about it and put in the bypass, but complimented me on keeping the coolant so fresh.
 
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