2003 Infinit G35 Sedan, bought last year with 124K on the odometer. Car was VERY well maintained, service records, etc. It is in amazing shape considering its age, there was not so much as a door ding on it! This is for my 17 year old and he just started driving it almost daily to school and back last month. Had it since last July.

Have had a continuing problem with the car overheating. It runs up to halfway on the gauge, stays there for 10-15 minutes of driving. Doesnt matter if it is hot (90 degrees) or cold (30 degrees) out. A/C blows cold, heater blows hot. After 10-15 minutes of driving, needle spikes towards the H mark on the gauge.

It will spike and then stay there, driving on the freeway, etc, doesnt seem to make it drop but maybe one hash mark.

I first tested the clutch fan and replaced it as it spun easy after being warmed up. Didnt help. I got a Linse Funnel system and attempted to bleed the air out thinking that might be it. Didnt get much in the way of air bubbles, I also used the bleeder valve. Didnt help.
Checked upper and lower hoses, both hot.

Yesterday, I replaced the thermostat.., bled the system again,,.drove it 10-15 minutes with the AC on, came to a light, climbed up just past halfway, took off, it dropped below halfway. Drove another 10 miles and all of a sudden, it started climbing as I was driving about 35 mph up a hill. Then it just stayed there. My son drove it about 10 miles today with the AC on, (90 degree day) and he said it spiked very close to the H on the temp gauge.

What else could it be? Radiator and temp sensor valve or my next likely culprits? Watrer pump possibly? Did I get a defective clutch fan perhaps? After it warms up, the fan spins freely?

Any help is GREATLY appreciated. Other than this issue, the car is awesome. I drove it last night after the thermostat swap and am always amazed out how nice it drives.

 

Park the car on a steep hill, front end up. Take the radiator cap off (be careful) and start the car with the heat on full blast. There is either a huge air bubble trapped (doubtful), the radiator is clogged (doubtful), or the water pump is bad (most likely). I wouldn't be driving the car around a lot though, it would be pretty easy to warp a head with high heat. And I thought all G's came with electric fans and not clutch fans...?

 

I know when I pulled my engine the second time I had the same issue. I have an 05 so I don't know if the cars are set up the same. There is a bleed port located on the passenger rear side of the engine bay. It's a big Phillips head black plastic connection. I had to open this up and slowly (I can't stress enough how long this took compared to any other vehicle I've owned before!) fill until the air is out. It took quite a bit of time, but fixed the overheating issue.

 

oh that's filling it through the radiator not the bleed port. didn't clarify that

 

So.ething I see people screw up regularly is adding coolant too fast. It should take you one full minute to add a gallon of coolant, if you dump it in fast you trap air.

 

Thanks for the replies, I will attempt to try to remove trapped air again and see if that helps. I bought a lisle funnel for that purpose and also used the bleeder valve by the battery. I will report back....thanks again!

 

I believe '03 was the only year with a clutch fan. Their is a secondary electric fan for the A/C and I have seen that one cycle on and off.

 

First thing I would do is take the old thermostat and stick it in some boiling water. If it doesn't open and closes than you know the problem was that and you just need to get rid of the air.

You said that driving around 30-40MPH on the highway does it still get that high? If so than I would look more so at a clogged radiator or messed up water pump. The water pump is driven by the timing chain and doubt it's bad though, unless the impellers rusted off. I replaced my water pump about 3-4 years ago and it's pretty intensive if you've never done it before.

I also replaced my radiator, since it was leaking along with my cooling fans, because the motors seize. The motors seized on me again not even a year later.

I don't think it's your fan, since it mostly comes on when you have the A/C on and at an idle. Since, my cooling fan motors seized yesterday; if I drive 30-40MPH, heat on full, and with the A/C off I can usually keep my temp below < 200. It's when I stop that I start to sweat and it's not from the heat, lol.

 

If you file the inside diameter of a bottled water opening, it will fit snugly over the bleed valve. You can cut the bottom of the bottle off and now you have a funnel. Just remove the bleed screw (engine cold)

I do this to get air bubbles out while the engine is still cold, replace everything. Drive it around to operating temp and let it cool for several hours. The reservoir should get sucked in the radiator to displace most the remaining air.

jy

 

Hi Guys I'm new to this forum.
I"m having similar issues. I've replaced everything radiator, thermostat, radiator fans and I'm Still having overheating issues. 06 G35 Sedan 79K. Sorry not trying to thread jack....