... is there any other reason for this to happen?


Start the car, drive short distances around town and temps are fine. Drive for extended periods or on the highway, slow down and temps start to climb. After a couple days of driving the coolant level will drop. When the car seems to be heating up the coolant overflow is usually FULL, like the coolant is just going in to the tank.


There is NO coolant mixing in to the oiling system. There SEEMS to be no coolant burning out the exhaust. The only time you can smell coolant is when the overflow tank is actually overflowing and coolant is spilling out. A/C works just fine, but no heat.


Things that have already been replaced:
New Radiator
New Thermostat
New Upper and Lower Radiator Hoses


I have already purchased the head gasket set, I just want to make sure there is nothing else that I could be missing that could cause this before I get into changing the head gaskets, taking the heads to a head shop to be checked out and resurfaced/decked if they need to be kinda thing, plus blah blah whatever else I'll end up having to change if I do that.

 

Have you confirmed that you fans are working properly and that the coolant is actually circulating when the thermostat is in the open position?

 

do a compression test.

 

I can let the car idle all day and the temps are fine. Both fans are working properly, while the car is idling you can hear the low speed fan turning on and off, turn the A/C on and the high speed fan turns on as it should.

 

I was just thinking about this when I read the thread about the 03 overheating at highway speeds and saw someone's explanation about their Mustang doing the same thing and it turned out to be a combustion leak. I'll have to get a hold of a compression tester first as I do not have one my self.

 

I was also just going to mention the fans.

I just helped a friend do a motor on a Saturn vue, it was doing the same thing as yours for a LONG time (no oil/coolant mix, no smoke out tailpipe, just overheating on highway, loosing coolant from the overflow) It eventually got bad, overheated with no coolant in it, and started running rough only to not restart. Still no mixing or smoke but compression was between 20-70psi in all 4 cylinders when I got called in (1st thing I did after looking at fluids was checked compression).

Anyways, I would NEVER do a headgasket on a VQ with a blown headgasket (I've done several, on motor builds).

DE-k's can be had for the same price you will spend on parts & machine shop labor, and doing the headgasket is more labor than replacing the motor, the whole drivetrain drops out of the bottom pretty easy (even without a lift). I could have the whole drivetrain sitting in front of the car in the same time it takes to remove the rear manifold. My .02c

 

Have you purged air out of the system. Take the radiator cap off, raise the front of the vehicle and run for 15-20 minutes in idle.

I would also replace the radiator cap.

Head Gasket is a very remote possiblility. According to an expert head gasket issues on a VQ is unheard off though it is quite common on some of Nissan's smaller engines like the notorious 1.8L in the sentras.

 

some times with nissan you will get a air pocket and the cooling system will need to be bled to release the air pocket. also id check the rad cap.

 

I am going to try this and see what happens, is there a specific angle or just as long as the front of the car is in the air?

 

if head gasket is blown, you should see white smoke comming outta your exhaust.

 

I know that's why I said there is no coolant mixing into the oiling system or the exhaust. Talked to someone yesterday that had worked on a VQ30 with a similar problem and he said it was the water pump. So I am going to try to change that out sometime today and see how that works out.

 

Sorry for the crappy phone pics.


Using THIS WRITEUP my self and one of my friends changed the water pump on the Maxima, and bleed the cooling system, in just under two and a half hours. Now everything is back to normal, it was not a head gasket so I am glad I tried this first.


Although "visual inspection" of my old pump shows no real sign of any wear, everything appears to be good.








But upon closer inspection the weep holes in the original water pump are extremely corroded and clogged up, no picture was too hard to get a good one with my phone. Also the impeller is slightly farther off of the shaft than the replacement one is. It would seem the impeller was trying to "walk off" the shaft under pressure.


Old:




New:




So the heater seems to be working as it should now and the cooling system is also working as it should. I drove around trying to see if it would fail, but it did not. Drove around for an extended period keeping the RPM's in the 3500-4000 range and the car never so much as hinted as to be heating up.


So before you go spending $XXXX on head gasket replacement and/or motor swap, go spend ~$80 on a new water pump and some new coolant and see if that could save you some money.

 

I know how that feels. That was one of my fears when I was having my overheating issues. Your impellers don't look that bad at all; here are pictures of my old and new pump when I did mine:





Glad it worked out for you....

 

I had just seen your pictures the other day, which is one of the reasons that when I pulled mine out I was like son-of-a-$&*$, lol.



Drove around some more and so far so good, no heating up or anything yet, but the heat seems to be hit or miss. Hoping that there is still a small air pocket that needs to be bleed out or maybe my "new" thermostat is stuck open. Probable going to take a look at the thermostat this weekend.

 

If a thermostat sticks open, the problem will be that the engine will take a long time to warm up to normal, if it can even warm up enough (like in a cold climate). If the temp guage indicates normal temp and you don't have heat, you most likely have an air pocket. The old 3rd gens had to be jacked up until the rear bumper touched the ground!

 

Should also give you an SES light.