Hi,

I have a 2003 G35 Sedan.

My car overheated today. I stopped the car & check to see if anything was leaking. I saw the reservoir was full about to the top. Last week i only fill it to the Max line of the reservoir & today it went about to the top. I let the car cool down & check the coolant level & it is fine.

My A/C fan comes on when is A/C is turn on. My fan clutch is spinning fine. I am thinking my thermostat but dont' know what to check for.

Your input is greatly appreciated. Thanks in advance.

 

Are you checking the level of coolant in the radiator itself or just looking at the overflow bottle? If there is a leak in the cooling system it will not properly draw fluid in from the overflow.

 

i checked both once the car overheated.

overflow (reservoir) was too the top of the bottle..not normal

radiator - check after letting the car cool down & it was not missing any coolant.


got me scratching my head wondering how my car overheat & all fluid are there & more..

 

Ok, perhaps mods can sticky this for all the 03-04 g35's with FAN CLUTCH setup.


First questions that need to be asked in the event of the overheating problem with the 2003-2004 G35 sedan


1. does it have a fan clutch?

if so, when does the car overheat?

A.) After driving on the road/highway and getting off the highway

or

B.) In bumper to bumper traffic


If (a) then you must check for proper function of the fan clutch


if (b) you must check for air in system.


First step is to test the functionality and worthiness of the fan clutch itself.

How to check?

(there is NO set method to check a fan clutch just takes experience)

one way to test it which is STRONGLY advised to exercise caution is to grab a news paper and make it into a Strong rigid ROLL. once you've had the car turned up to standard operating temperature is to open the hood with the engine on and SLOWLY attempt to stop the fan. If your fan stops, toss it! If the paper just gets shredded and the fan does NOT slow down or make an effort to stop it's good.

if the fan is bad replace it. refill the radiator and proceed to proper bleeding instructions per Infiniti FSM.

If the fan is good then you may have air within the system.

If you have air you need to properly purge the system. One tool that I have found to work phenomenally well is NAPA spill free funnel kit part number 77-4000



With this tool you'll end your troubles quicker and safer.


If your trouble continues you must change your thermostat and re-bleed the air out of the cooling system.


one day to bleed the car quicker and more effectively is to disconnect the front 16inch auxillary fan from the car. Once you've done that you have to be more alert of the temps as you will not have that added protective layer that Infiniti created for the engine.

the fan kicks on at 203 degrees at 50% power and at 215 degrees it shifts on to 100% power.

The water begins to boil over at 210 degree's and radically boils over after that.

You'll disconnect the auxiliary fan attempt to overheat the car by revving the engine to 1,500 to 2,000 rpm. once you've achieved the boiling effect turn off the car allow fluid to come to a calm and then refill the bucket asap. Reconnect the auxiliary fan turn on the car and immediately fill the bucket so no air is introduced into the engine all in the mean while keeping an eye on the temperature sensor and while having the heater on full blast 90degrees.

within 10 minutes you can bleed the entire engine.


if you continue to have overheating issues you may have a warped head and if thats the case you need to rebuild your upper motor or just buy a newer / used motor.

You can test for this by purchasing a exhaust leak detector fluid thats poured into the radiator and if it turns a certain color it's bad.

 

Thanks for input..

Update..

i replaced the thermostat but it is still overheating. i tested the old thermostat through the stove test & it opened a little bit.

I've read some thing about bleeding coolant. Lisle funnel: can i do this by myself or i need 2 person? Yes, i see the part number on Napa store & we have a store in houston..yay!!

One last note, when i start the car with the radiator cap off, the coolant would spill out after 1 min. A friend mentioned that it is suppose to suck in or something but not spill out. With the coolant spilling out, does that mean air is inside & needs bleeding?

The plan is to bleed the air out of the system w/ Lisle funnel & if still overheat, will replace water pump.

Thanks again for your assistance.

 

Today, i tested the car after thermostat replacement.

I drove inside road & freeway for about 20 min. no problem. i went back to the house & check the engine & again i noticed the coolant reservoir (overflow) was almost to the top again. Before testing it was below max & coolant on radiator was at good level. The coolant is going to my coolant reservoir & it is causing it to overheat. That is what i notice.

 

Sounds like head gasket issue. or stuck thermostat

 

head gasket

 

Did you replace the rad cap with a new OEM one?

 

update...

i try bleeding the coolant. sorry eric, i couldn't man up & did the way you mentioned about the auxilary fan.

left the car on idle & heat manual full blast at 90 degree. about 30 - 45 min in, 3-4 small bubble was appearing druing the 45 min. i try to rev the engine a lil bit to 1500rpm after 45 min. stop reving. & while waiting about 1-2 min after reving, the coolant was overflowing & i can see bubbles like a volcano erupting. i let it overflow for a bit, maybe 1 min. & stop the car engine. when the engine was turn off, i see big bubble still on the funnel & coolant went down back into the engine.

i will attempt to do it again & see if the same thing happens.

thanks again for input & i will update.

 

i rev to 1500rpm for maybe 1-2 min before stop reving...

 

Once the funnel sucks all the fluid in immediately fill it backup so you wont introduce air back into the system.

 

sorry for not enough details...

the coolant went down after i turn the engine off but it was very little left back. i waited for all to go down before putting the radiator cap back. it was probably 5 min or so for the coolant to go down completely.

 

your system is air locked. You cannot bleed the system without loosening the bleeder valve.

try and follow these steps.

1) top the system off with funnel in place.
2)) start engine and set heat control
3) Loosen bleeder screw approximately once every minute until air bubbles no longer come out of valve. Tighten screw and repeat every minute.
4) MOST IMPORTANT. Monitor your upper hose temp. If your upper hose starts to get really hot and the bottom hose it still cool, TURN OFF THE ENGINE because the system is about to boil over. Let the engine cool for about 5 minutes or until you can comfortably grab the upper hose without getting burned. During the cool down, the heat of the coolant should have spread and started to crack the t-stat open. When you restart, you should feel the lower hose starting to get warm as the upper hose heats up again. It's up to you to monitor the upper hose temp and shut it down again if it get too hot and the lower hose is still could. DO NOT LET THE SYSTEM BOIL OVER otherwise you're starting from square one.

Let me know if you need clarification on anything. I know it is a bit confusing.

 

hmmm... i do need clarification...

- bleeder screw: this is my 1st time see the way you do yours. i normally see loose until the coolant squirt out. i try not to mess w/ the bleeder screw so I do not know how it goes.

- step 4: not sure what we are trying to do here w/ starting & shutting down the engine. i have the napa funnel to assist w/ the bleeding.

i am in houston (C.S.T). i am looking to attempt to do the bleeding again in the morning. if you can PM your number & i can call you to discuss the process if you have time.

thanks again for your input