air bubble inside my heatercore? how to fix it?

[ddemier7]

Ive always notice a gurgaling or swishing sound coming from my heater box behind my dash. I think i got an air bubble in my cooling system, car does not run warm just a slight gurgaling noise can be heard upon start up for just a min. Isnt there a purge vavle by the battery compartment for a 2003 g35 coupe? How do i get air out of my system the easy way? What does this valve look like? Park the car on a incline and purge this valve? Any ideas??

[AZhitman]

I always put the front end up on ramps, run the motor with the rad cap off (not for long, just until the t-stat opens), and top it off.

My G always gurgled a little, though.

[Fezzik]

This is exactly what I have done on all my cars when I drained the fluid. The problem is sometime is can boil out. Not a big deal. just a clean up mess. I've gotten one of these now.
http://shop.advanceautoparts.com/webapp ... 22970131-p

The Nissan cap is the same as ford. they cost about 30 dollars.

[ddemier7]

Actually i have a yellow spill free funnel.

[ddemier7]

Car is not overheating but theres still no heat coming through vents! Where are the heater core hoses located and are they access through the top or bottom?? Its sooo compact back there im not even sure to get to them

Is there a bolt on the engine block to access and help perform a flush. If so where is this bolt located. ??

[Fezzik]

If your not getting heat, maybe the thermostat is gone bad.

[ddemier7]

Whenever I drive its getting a liitle heat now but when its at idel it starts blowing cool air. I think im just gona take it and have it flushed and vacumed all the air out of the coolant system. New thermostat after a complete flush.

[Fezzik]

Well if its a 2003, the symptoms still say thermostat to me. I'd shoot for a new thermostat before the flush because you have to drain the system anyway to put in the new thermostat and its really not that hard to change on our cars, if you look at the FSM (factory service manual) you can see it being done. Its either the thermostat or an airlock in the heater core.

EDIT: Here I even found it for ya! Thermastat is about 30 dollars from a infiniti dealer on ebay.
pg 24 for thermostat change, or just flush is on this pdf as well!
http://www.nicoclub.com/FSM/G35/Coupe/2003/co.pdf

Good luck and let us know how it works out

[ddemier7]

Thanks Fazzik!! I read some other articales on google and they said they had dealer or jiffy lube vacume air purge system and they were having same symtoms as I am. Im thinking weak thermostat and/or air still trapped in there that i am unable to ectract. Prob just have a reputable shop service it ... Flush, vacume air out and change thermostat out.

[SteveTheTech]

I get this question all the time and the answer is almost always the same.

As the bossman mentioned elevating the radiator making it the highest point in the system and allowing the bubbles to find their way out is a tried and true method of purging the system. However it does not always work and if it does it can take a very long time and spill coolant once you rev the engine a few times.

Here are a few things we have come up with over the years.
But first a quick caveat
We are going to assume you are doing this safely and know that the operating temperature of these engines hovers around 180F and the coolant can easily exceed 220F under normal conditions. Please be careful if doing this yourself.

One thing that is well established online.
2002+ Nissans and Infinitis all but require (there are a few TSBs about this as well) vacuum refilling with a minimum of 20 inHg of vacuum to be held on the system for a minimum of 30 seconds. (I have found pulling a strong vacuum exceeding 25" purging my fill line, allowing it to sit and pulling another 30 seconds of vacuum have better initial results than just a single session.)

If you do not have access to a vacuum purge I strongly recommend rethinking not flushing your own coolant. There are many non dealers service facilities that have technicians who own these tools, you should research before committing to having a service performed by anyone.
The big yellow funnels should work, but they are not nearly as reliable. (I have tried, several times before biting the bullet and buying the several hundred dollar vacuum refiller)

With the cooling system at full pressure you can open purge valve screw to allow extremely hot pressurized steam to escape from the outlet side of the heater core. The best way to do this is to have someone run the engine between 1500 and 2500 rpms in Park. Extreme caution must be used here. If you allow the steam to escape until coolant starts to bubble out you should be able to remove the trapped air pocket.

My preferred method, and by far the cleanest is to drive the vehicle in manual mode at high engine load (not high RPM) for several bursts over the course of a few miles. An course I frequently use is a stretch of road with repeating red lights about 1/4 mile apart, I make a loop through a nearby park at low engine speed to allow the engine to cool slightly and accelerate (safely) out somewhere between 3.5K-5K in second with my foot to the floor. Accelerating hard but not recklessly, what you are trying to do is move as much coolant through the heater core as possible. High engine rpms would do it but realistically there is no need to risk damaging the engine (this is most important for me at work). One trip will typically do it, I return to the shop at a normal pace and park the car where it can sit and allow the radiator cap to do its' job. I typically fill the coolant bottle about 1-1.5" over the Max line and allow about 30:00 for the car to cool and coolant pressure to stabilize.

[ddemier7]

I took my car to a reputable mechanic 18 miles across town. When I arrived I noticed my heater was working fine and informed mechanics that the g35 probably burped itself on the way over. The shop called me a few hours later and notified me that the g was operating fine. I said its already there so lets do a flush and vacume air out of the cooling system and call it good to go.

is this not wierd or what?

[SteveTheTech]

I've long suspected the cars have a level of spite based intelligence. They seem to know when you are going to have them fixed and will some times fix themselves or be quite when a pro is looking it over.

It happens all the time.

At least your issue seems to be resolved.

[ddemier7]

so far so good... I would reccomend if anyone is having similar issue just drive it around after your flush and fill. burping it first then drive and let car do the work.