Hello All. I am new around here. This is my 1st post actually. I have an issue and hoping you guys can help me out...

I have an 06 M35 with 175K+ miles on it. A couple of months ago as I was preparing to take a 5 hour road trip, the car overheats after about 45 min of driving. I pull over, shut car down and let it cool off. Once cooled, I started car again, drove only for a couple of minutes before the car shot back up in the red. Let cool off once more. Tried again, same result. I ended up having to tow the car back home. So, I'll give you guys a complete rundown on what I've done to the car thus far....

1. I changed the T-stat.
2. Refilled system, burped system 3 times, same results.
3. I rented tool from AutoZone to test for exhaust gasses in the coolant system & found none.
***I noticed that the top radiator hose has high build up pressure, so I...
4. Disconnected top hose from radiator & started car. There was no flow from the hose or the radiator.
*** After conferring with someone in the Facebook group with that finding, it was suggested that the water pump may have failed.
5. I removed, inspected (it showed signs of weeping) & replaced water pump.
6. Refilled with water only to test out, as I didn't have money to throw away coolant.
7 . I let car idle for about 10 minutes on incline, with heat on full blast. the car did not overheat at all during this time. I burped the system approx. 3 times during this time.
8. Took car for test ride for about 30 min. Car did not overheat.
9. Drained system, replaced water with coolant.
10. Repeated steps 6 & 7. However, this time the car began to over heat again.

Now, at this time, I'm noticing that the top radiator hose is under extreme high pressure again. As I'm attempting to use the purge valve to bleed, the pressure there. Let cool down. I took it for a spin around the block after cool down and it over heated quickly. OMW home, the top hose just popped off the neck of the radiator!

* Overall, What I've noticed is that there are different times as to when the car will overheat after cool down temp anywhere between after 3 min to 10 min.
* The bleeder screw is also under same pressure and while hot, its almost impossible to relieve the pressure.
* Still no flow through the system.

I'm really hoping that the head gasket is NOT blown. Could it be that the system is clogged somewhere? Heater core? Please help before I trade this thing in for a Sonata!

welcome to the forum...
Where have you been all this time!

You did not mention your cooling fan operation at all in your post, unless I missed it!
The fan controller, attached to the fan(s) bracket, was a problem on early builds 06 M's
It was covered by a recall.

Are your fans working? What is the build date on your car?

Burping these cars can be difficult. Are you using a burping funnel to assist you in getting the air pockets out?

Thanks Steve....
First, yes both fans are working as should be. And yes, I am using the burping funnel as well.

The most severe symptom I'm noticing is the high pressure on the upper hose and radiator.

steve_c wrote:welcome to the forum...
Where have you been all this time!
...

Right? Lol.
We do seem welcome members fighting fires right out of the gate, but neverthelesss we love to welcome people. Welcome aboard!

1. I have a question on the type of coolant you are using. Is it concentrate or 50/50?

2. Have you checked the FSM? There should/might be another thermostat in the back of the engine. It is usually located in the valley and might be referred to as a proportioning valve.

3. On blockage and restriction, can you force feed water into the inlets for both heat exchangers (front rad and heater core) and see if water comes out of the other end?
I don't think the heater core will be it though, because that is a passive sytem that can be bypassed, and its issues shouldn't make your engine overheat. Also, just check it by turning the heat on.

EdBwoy wrote:

steve_c wrote:welcome to the forum...
Where have you been all this time!
...

1. I have a question on the type of coolant you are using. Is it concentrate or 50/50?

2. Have you checked the FSM? There should/might be another thermostat in the back of the engine. It is usually located in the valley and might be referred to as a proportioning valve.

3. On blockage and restriction, can you force feed water into the inlets for both heat exchangers (front rad and heater core) and see if water comes out of the other end?
I don't think the heater core will be it though, because that is a passive sytem that can be bypassed, and its issues shouldn't make your engine overheat. Also, just check it by turning the heat on.

Thanks EdBwoy...

1. I have tried both.

2 I have checked the FSM. However, I did not see mention of a second t-stat or proportioning valve.

3. So what I JUST did was run a hose into the top of the radiator neck, no flow out of the upper hose that's connected to the heater core. Ran same hose into the upper hose, no flow out of the upper radiator neck. This was done with engine off.

I had the same type of issue with my 04 Lincoln, I changed the thermostat 2 times, the radiator hose, the upper housing....turns out the issue was the Degrass bottle (over flow bottle) had a crack in it... it wasnt leaking but it was messing up the pressure in the system creating the overheating problem.... so not sure if that helps...

3. So what I JUST did was run a hose into the top of the radiator neck, no flow out of the upper hose that's connected to the heater core. Ran same hose into the upper hose, no flow out of the upper radiator neck. This was done with engine off.

Engine off might be the issue here as the pump isn't turning, thus just acting as a closed valve.
Disconnect both hoses that come from the radiator and test it like that.

Any idea if some form of radiator stop leak has been used in that vehicle?

[Duplicate post]

Well,
Sounds like you are pretty competent in diagnosing & wrenching.
Any chance you installed the T-stat incorrectly, or that it (the new T-stat) may be defective?

When you say fans are OK, that is to say you actually see the overheat condition taking place with the fans running, having no cool down effect?
Is your A/C condenser & radiator free from external debris blocking air flow?

If it were my car, I would remove the T-Stat, leave it out & reassemble to see if you get flow action without it. Also, with burping, putting the car on an incline (nose up) while using the burping funnel helps. I have had to bleed off some air at the coolant service port located on the R/S of the engine near the firewall (I think you said you did that). Use precautions when bleeding at that port.

With your VIN in hand, try calling Infiniti USA (or a dealer) to see if your VIN was part of the fan controller recall.
I have an early build VIN (car built 6/05) and my fan controller started operating erratically after about 4 years of service (summer of 2009 I think it started to intermittently overheat).

I know I do not have to warn you, but be extra careful while servicing/burping a coolant system, & diagnosing an overheating condition.
Should a hose let go, or the cap, etc. the escaping steam would be merciless on your flesh.
Over the course of my career, I have worked with many fellow mechanics who suffered varies wounds from car/truck repair,
but the ones that stand out in my mind are the ones permanently scalded by overheating vehicles!
Be super careful

Post Note:
I see from your OP that you burped on an incline! Very good!

EdBwoy wrote:

steve_c wrote:welcome to the forum...
Where have you been all this time!
...

Right? Lol.
We do seem welcome members fighting fires right out of the gate, but neverthelesss we love to welcome people. Welcome aboard!

Ahhh Yes!
But this one looks promising....maybe he will decide to join us and learn the ways of the force.....

EdBwoy wrote: Engine off might be the issue here as the pump isn't turning, thus just acting as a closed valve.
Disconnect both hoses that come from the radiator and test it like that.

Any idea if some form of radiator stop leak has been used in that vehicle?

I was hoping I wasn't THAT stupid, but apparently I am....lol. I really thought about that AFTER I posted what I did.

The radiator is about 6 months old, as I had to replace it because the previous one burst. So, no stop leak.

steve_c wrote:Well,
Sounds like you are pretty competent in diagnosing & wrenching.
Any chance you installed the T-stat incorrectly, or that it (the new T-stat) may be defective?

When you say fans are OK, that is to say you actually see the overheat condition taking place with the fans running, having no cool down effect?
Is your A/C condenser & radiator free from external debris blocking air flow?

If it were my car, I would remove the T-Stat, leave it out & reassemble to see if you get flow action without it. Also, with burping, putting the car on an incline (nose up) while using the burping funnel helps. I have had to bleed off some air at the coolant service port located on the R/S of the engine near the firewall (I think you said you did that). Use precautions when bleeding at that port.

With your VIN in hand, try calling Infiniti USA (or a dealer) to see if your VIN was part of the fan controller recall.
I have an early build VIN (car built 6/05) and my fan controller started operating erratically after about 4 years of service (summer of 2009 I think it started to intermittently overheat).

I don't think installed the T-stat incorrectly. I did check the new one before installing, via the boiling water method, to see if it would open @ before 212*. Then tested it again vs the old one. Both opened at the same time.

As far as the fans, yes, the overheating condition occurs while the fans are ON. No debris on the radiator or condenser either. My driveway is on a steep incline, so of course I used it to help bleeding. (I also tried ramps as well.)

I'm going to go start the car with the T-stat in place first to see if I get some flow via the garden hose now.

I have checked the FSM. However, I did not see mention of a second t-stat or proportioning valve.

You are right about this. I dealt with a pathfinder engine and didn't know the sedans got the VQ35 without the secondary valve. It only made sense to me to have it, as it did to whoever designed the M45 V8 apparently.
Even if this valve were an issue though, it shouldn't block flow.
Interesting read: http://vq35.com/2010/07/go-with-the-flo ... ng-system/

steve_c wrote:

EdBwoy wrote: Right? Lol.
We do seem welcome members fighting fires right out of the gate, but neverthelesss we love to welcome people. Welcome aboard!

Ahhh Yes!
But this one looks promising....maybe he will decide to join us and learn the ways of the force.....

Please, show me the ways! lol

Soooo.....
I just started the car, let it idle for a good minute with the heater on at full blast. There is still no flow from the upper hose. As I understand it, the flow should be from the radiator thru the lower hose to the T-stat, into the water pump, into the heads & block, back around to the upper hose, correct? I am getting NOTHING out of the upper hose.

What happens if you feed something through the upper hose into the radiator - will it drain at the bottom?

Also, while doing the running tests and purging it, have you squeezed the bottom radiator hose until you see water out of the top radiator hose?
What I'm trying to see is:
- Is the radiator actually full of liquid?
- And once you isolate the rad from the rest of the system, is it actually allowing fluid through?

EdBwoy wrote:What happens if you feed something through the upper hose into the radiator - will it drain at the bottom?

Also, while doing the running tests and purging it, have you squeezed the bottom radiator hose until you see water out of the top radiator hose?
What I'm trying to see is:
- Is the radiator actually full of liquid?
- And once you isolate the rad from the rest of the system, is it actually allowing fluid through?

The radiator flows. Feeding water into the radiator thru the top, flows it out of the bottom. Now, I wouldn't know how to isolate the radiator from the rest of system to check for flow through the rest of system. I'm going to remove the T-stat now though...

I'm going to remove the T-stat and see if I get flow through the entire system at all now.

Fugaman, could you post some pics of your engine bay showing the layout of the hoses, radiator & inlet pipe. I got mixed up looking it up online.

Here are some ways to upload pics:
1. using IMGUR
2. using PHOTOBUCKET
3. using TINYPIC

EdBwoy wrote:Fugaman, could you post some pics of your engine bay showing the layout of the hoses, radiator & inlet pipe. I got mixed up looking it up online.

Here are some ways to upload pics:
1. using IMGUR
2. using PHOTOBUCKET
3. using TINYPIC

I'll get to this shortly.

OK, so I removed the t-stat from the housing, reinstalled and now I have flow. So that tells me that the t-stat isn't opening/closing properly. I just don't know why. I call myself doing the boiling pot water test before installation to see.
What are the dangers of running the car without a t-stat for an extended period of time?

steve_c wrote:Well,
Sounds like you are pretty competent in diagnosing & wrenching.
Any chance you installed the T-stat incorrectly, or that it (the new T-stat) may be defective?.......If it were my car, I would remove the T-Stat, leave it out & reassemble to see if you get flow action without it. Also, with burping, putting the car on an incline (nose up) while using the burping funnel helps. I have had to bleed off some air at the coolant service port located on the R/S of the engine near the firewall (I think you said you did that). Use precautions when bleeding at that port.

Fugaman wrote:OK, so I removed the t-stat from the housing, reinstalled and now I have flow. So that tells me that the t-stat isn't opening/closing properly. I just don't know why. I call myself doing the boiling pot water test before installation to see.
What are the dangers of running the car without a t-stat for an extended period of time?

Fantastic!
I think for the summer you will be OK without a T-stat. Winter is another story. T-Stat lets coolant & oil warm up quickly to operating temps so impurities can start boil off in oil & OBD can go into closed loop quickly, thus controlling emissions. You want the oil to be at engine operating temps to reduce engine wear.

Go for a Nissan OEM T-stat next time around. Are you 100% sure you did not install the stat upside down?

steve_c wrote:
Fantastic!
I think for the summer you will be OK without a T-stat. Winter is another story. T-Stat lets coolant & oil warm up quickly to operating temps so impurities can start boil off in oil & OBD can go into closed loop quickly, thus controlling emissions. You want the oil to be at engine operating temps to reduce engine wear.

Well, at this point, I'm wanting to trade the car in as I need something a bit more reliable.

steve_c wrote:Go for a Nissan OEM T-stat next time around. Are you 100% sure you did not install the stat upside down?

I'm pretty sure, as Autozone sells the entire unit, complete with housing and all.

EdBwoy wrote:Fugaman, could you post some pics of your engine bay showing the layout of the hoses, radiator & inlet pipe. I got mixed up looking it up online.

EdBwoy, here you go. The coolant flow circuit goes from left(upper radiator hose, to right. What is happening is with the T-stat in (right side) I'm not getting ANY flow from the upper hose on the left. This is causing extremely high pressure on that hose and when the bleeder valve is opened, it spits & sputters any liquid and vaporizes it. With the T-stat out, it flows and there is no pressure or overheating.

Issue resolved. It was the T-stat. Problem was i was using an AutoZoo T-stat. Went to Nissan & got one. Problem solved.

Thanks for the pic Fugaman.

Glad you were able to find a solution and post the results here.

steve_c wrote:

steve_c wrote:Well,
Sounds like you are pretty competent in diagnosing & wrenching.
Any chance you installed the T-stat incorrectly, or that it (the new T-stat) may be defective?.......If it were my car, I would remove the T-Stat, leave it out & reassemble to see if you get flow action without it. Also, with burping, putting the car on an incline (nose up) while using the burping funnel helps. I have had to bleed off some air at the coolant service port located on the R/S of the engine near the firewall (I think you said you did that). Use precautions when bleeding at that port.

Fugaman wrote:OK, so I removed the t-stat from the housing, reinstalled and now I have flow. So that tells me that the t-stat isn't opening/closing properly. I just don't know why. I call myself doing the boiling pot water test before installation to see.
What are the dangers of running the car without a t-stat for an extended period of time?

Fantastic!
I think for the summer you will be OK without a T-stat. Winter is another story. T-Stat lets coolant & oil warm up quickly to operating temps so impurities can start boil off in oil & OBD can go into closed loop quickly, thus controlling emissions. You want the oil to be at engine operating temps to reduce engine wear.

Go for a Nissan OEM T-stat next time around. Are you 100% sure you did not install the stat upside down?

I mentioned the T-stat a few times in my response to the OP above. Many aftermarket T-stats are generic and may not be specifically engineered for the application at hand.
I am glad we were able to assist the OP. Was your original T-stat defective?

steve_c wrote:
Go for a Nissan OEM T-stat next time around. Are you 100% sure you did not install the stat upside down?

I mentioned the T-stat a few times in my response to the OP above. Many aftermarket T-stats are generic and may not be specifically engineered for the application at hand.
I am glad we were able to assist the OP. Was your original T-stat defective?

The 2 T-stats that I had prior to my current one were AutoZoo T-stats. I don't think the 1st one was defective, but the 2nd one definitely was. Looking at them both, The OEM Nissan one is definitely of a better design & build.

Thanks so much for y'alls input!

2006 M35 Sport Overheating

It overheats when going up hill