Hello - consider me a frustrated G35 owner. My car has had bouts of overheating and I have already put a decent amount of money into this thing. I have read many other threads on this forum regarding the bleed process. I'll explain my issue to see if someone has an idea...

G35 Sedan, 05'
95,000 Miles

1) Car will overheat
2) I hear some gurgles under the dash (air pockets)
3) Reservoir is constantly at different levels after it has cooled off. I don't think it is sucking back in the coolant after cooling off. Of course, it did a few times.
4) Sometimes the heat will no longer work.
5) When I opened up the bleeding screw after the last bout of overheating (needle only got to 1/2, normal is 3/8ths position) it ran DRY. There is no no coolant coming out of the bleeding screw, at all. HEAT is on in the cabin, of course, no heat.
6) I have filled and bled the system countless times now, according to the many threads on this site. I just seem to be getting new air into the system.
7) When the engine was cold, I fired it up with a air tight funnel and looked for bubbles, no bubbles in the radiator.
8) When the engine was cold, I drained some coolant from the radiator and then used a 'block tester'. Ran the engine for like 5-10 minutes and the color didn't change even slightly. IT was as blue as it was in the bottle, despite be squezing that suck a good 300 times.
9) Tried the block tester on the reservoir, same thing - hydrocarbons came up negative.
10) Took this to a mechanic shop BEFORE I did these things, and they said they could not get it to overheat or cause a problem. Not a bad shop, but I don't think they know what it is. Anyhow, they replaced the radiator and thermostat. I believe the thermostat was after market.
11) Fans are spinning plenty fast. They turn on when they should...
12) When it overheats, I lose coolant from the radiator reservoir hose. It boils/steams it's way out.
13) Engine doesn't misfire
14) Flooring the engine doesn't cause an overheat.
15) Mechancic Pressure test was done the cooling system. Held pressure overnight.
16) Mechanic did a compression test initially, came up negative (this was 2 months ago)
17) 89,000 Miles....
18) seems to keep getting new air...

Now my Mechanic and infiniti say 'head gasket' most likely... The dealer say they could do an engine swap for $5,000 including parts and labor. Of a HG replacement for $3,000. Any ideas? Real frustrated.

I cannot put $3,000 more into the car... I am at about 2K in the last two months. Sell for salvage?

 

Our cars are notorious for being super hard to bleed all the air out. If you hear gurgling in the dash that's air in the system. Just keep at the bleeding process until it's removed. If you open the bleeder screw when the engine's hot then you have an issue with the thermostat or not enough coolant in the system. Test the bottom radiator hose with the engine warm, if it's not hot the system isn't working correctly. At that point I'd replace the thermostat with the OEM part then go from there...........

 

If the head gasket is leaking, the tell tale sign is white smoke coming out of the exhaust and smells like coolant. The white smoke is the water vapor.

After bleeding, I would only add coolant into the expansion tank, not through the radiator cap because that would induce more air into the system. I just don't think you are bleeding correctly, and it's not necessary to add more coolant after bleeding unless the level is really low, but do it through the expansion tank!

 

Thanks for the responses. I can try and rebleed it again. As far as I understand it. There are two guides I have followed that were specifically mentioned for our cars. Maybe you guys can tell me if I am doing it right or wrong.

1) Front of car elevated
2) Air tight funnel - poured coolant/water until funnel was near full
3) Opened the bleeder valve near the battery compartment and watched the fluid pour out as the funnel start to empty... (made sure the funnel didn't go empty) opened the bleed valve and did this a few times until I felt most of the air was out.
4) Started the car, turned the HEAT on and let it run for a bit - opened the bleeder valve and watch bubbles (air? exhaust?) come out of of the bleeding valve... Once it ran smooth, closed up the the bleeder valve.
5) Revved engine to 3K for 10 or so seconds a few times and opened the bleeder valve, watching more air come out.
6) Took it for a test drive around the block. Opened up bleeder valve again... Keep getting air and bubbles.
7) Took it for a longer test drive. Opened up bleeder valve again, still getting air and bubbles
8) Shut off car, turned it back on opened bleeder valve, still more air and bubbles.
9) let the car cool off for 6 hours
10) Took it for a drive - no issues...
11) Started it up Sunday morning and I heard some gurgling (something I didn't hear until this time)

No matter how much I open that bleeder valve, it always bubbles. I cannot tell if that is air, gas or just boiling coolant. Am I supposed to use that bleeder valve like I am?


Now... When I drove it to work this morning, it was fine for about 10 minutes and then the needle climbed. I pulled over, opened up the hood and opened the bleeder valve, tons of air came out... Drove it to work with the needle wanting to go above 1/2, but the heater core was kicking out enough heat to keep it into check. Parked it at work, opened the bleeder valve... EMPTY!!! Nothing left in it. Decided to post here, because I am not having any success with this car.

 

Ok, I followed these instructions in the video just now

http://www.infinitihelp.com/diy/gsed..._procedure.php

However, when I rev the engine, I hear some gurgling, but only when I rev it. When it idles, there is no such noise. Only when I start it, and rev it (right around 1500rpm I hear some moving water)...

At this point, that WOULD point to a head gasket... Yet no hydro carbons? Baffled and dissapointed. Can anyone confirm? Also that video doesn't really explain how to continue to bleed the air out. One guy posted NOT to remove the radiator cap, as that just introduces more air into the system... Others say to use the bleeder screw...

My father, who does auto-body, which also includes install raditors, water pump and basic mechanical said that even if these are hard to bleed, they shouldn't be THAT hard. No other car he has worked on(hundreds of radiators replaced) has ever given him the type of trouble I am seeing.

Thanks for the advice in advance...

 

You don't need to elevate the car when filling coolant, but that's not the issue here. I don't understand the word "funnel" in your steps 2 and 3. What do you mean by "funnel"? Expansion tank? By the way, our G is really not hard to bleed. I never had any issues like yours. From your description of bleeding, I don't see anything wrong.

Are you losing coolant, not by bleeding, just losing coolant? If you don't see white smoke(water vapor) from your exhaust, you don't have a leaking head gasket

 

As for funnel - I meant that I used a funnel to fill the radiator so that the water level was the highest point and therefore, would force coolant out (and thus, air) of the bleeder hole near the battery. I had read a few places this was recomended, and it makes sense as I am not new to bleeding fluid lines.

I *WANT* to agree with you about the head gasket. Compression test the mechanic did when it first overheated came up negative and after a series of overheating, the hydrocarbon block tester came up negative as well. There is no white smoke, and as far as loosing coolant? I am losing a tiny bit each time it overheats. If it overheats a lot, I lose more because it is boiling right out the reservoir hose and reservoir itself. The mechanic did a pressure test on the cooling system and it held pressure overnight.

So, I don't particularly think it is the head gasket either. But the mechanic bled it, and after talking to his 'buddy' mechanic over at an Infini dealer for tips on bleeding it, did so and that was that. Still, even after he bled it, I heard a 'water fall' of rushing water behind the dash. I never knew it was a problem, and it didn't overheat for probably 2 weeks like that.

Now I hear water everytime I turn on the engine, and anytime it is revved past 1500rpm, despite bleeding it per the instructions. I used the bleeder screw everytime I took it around the block. It just continues to bubble out everytime I open the bleeder screw. I believe I did it over 7 times or so. It was running GREAT the evening I did that took it out for a bit of 'harder type driving and the needled was pegged at normal' then... came back in the morning and I had MORE coolant in the reservoir than before... That is strange, normally when the engine is hot, it sucks coolant back in as the temperature drops. But, this time the reservoir was higher after the engine cooled off. And... Guess what? It overheated first thing in the morning after about 5-10 minutes of driving.

 

The water noise you hear by the firewall is air trapped in the system. If you are not losing coolant like you said, then I would just continue to bleed it darn thing and see what happens. I don't see how the air gets into the sealed system???

By the way, I don't use the funnel like you described. It's not necessary. I just initially fill it through the radiator cap and bleed the system. Any more coolant needed is done through the expansion tank.

 

Spent another several hours bleeding the system. Basically determined that even after I get the air out of the system, more air enters. Therefore, it really can only be a head gasket. The radiator cap tested good and the pressure test on the cooling system held at 13 PSI overnight with no leaks when tested a few days ago.

Makes sense, when I rev the engine it probably leaks out the headgasket into the cooling system causing air to build-up. I can only remove the air from the car for a short while via the bleeder screw, it doesn't take long for more air to get introduced back into the system, which then quickly overheats. Baffled as to why the hydro-carbons come up negative, why a compression test on the engine passes, and why the engine runs so smooth, even when floored.

Being that this car has now overheated multiple times (hit highest mark twice) there is no doubt in my mind the engine is cooked. Probably a warped head. Brings me to another point - A real shame that with the advanced ECU's in these cars, they do not throttle these cars when the temp hits 240ish. The car never tripped an overheating code until a few days ago. It is laughable, that the car hits the highest temp on the gauge twice before, but now it doesn't even go 2/3rd's up and the the sensor is tripped for an overheating engine for the first time ever. Would have been nice to have received the warning before I cooked my engine. Maybe I am the minority when I say that I don't stare at my engine temp gauge while I drive... I might look at it every few minutes or so but that is definitely enough time for the needle to go "H" before you notice it. Oh well, such is life.

Anyhow, the car was great while it lasted. Now, I get to decide what to do with it. Good condition overall, a real shame. Kinda bummed, but I have moved on now.

 

for the 2k you spent trying to fix this you could have already put in a used engine in the car

 

Hindsight is always 20/20. You don't know you have a bad head gasket when it tests negative with standard testing and you have a whole slew of other components in the cooling system to check and replace first. Head Gasket still passes standard testing, but that doesn't mean when they take it apart and look they won't find it damaged and warped, along with the head. To put it another way, when your car overheats, you don't just replace the engine. Of course, that would work, but if the cooling system components were to blame initially, then you will just bake your new engine.

Also, dealer quoted $5,000 for low mileage engine, and the labor to install it.

 

The dealer will ALWAYS charge out the ***, i would never get serious work from the dealer unless it was under warranty, but that said im the kind of person that would change his own engine before paying anyone, as for cooling components, if you replace the engine all you leave behind is a radiator and a heater core, both of which dont seem to be the problem.


wait did you check your heater core? it might be holding air in it somehow, you could even just bypass it to see if its the culprit. you never know, my friends s600 Mercedes was diagnosed with a blown head gasket and like 8k to fix it but we bypassed the heater core and he stopped loosing coolant.
you can go to autozone and get a hose coupler for like 3 bucks and unplug the 2 heater hoses that go into the firewall and connect them to each other

 

So what did you do after you bypassed the heater core? Anyhow, thanks for the suggestion.

I called a Nissan dealer, who are generally less expensive and he quoted me about $2500 for the head gasket.

 

tore open the dash and replaced the heater core, in my friends case it had a small leak and filled the box it was in so we cleaned it out and put a new one in and problem solved but for my jetta i just left it bypassed, it just means no heater. i doubt your burst or anything just may be full of air, if you bypass it you may find out if its the problem, if nothing changes then you can cross that one off the list, it just seems that if you dont have heat in the cabin then the heater core isnt getting water in it