Hey guys I am new to this forum and just bought my son an 05 G35 A/T. I am pretty mechanical but not familiar with the 3.5 engine and it’s possible quirks. Ok, the car has 104k clean carfax blah blah. Test drive the car and it drives perfect! Had it running for over an hour and no problems. Got it home and went for a ride and I noticed the eng temp rising, so I turn on heater to get some heat out to limp it home and no heater. It didn’t get extremely hot but did overheat. After letting it cool down I started it and it ran normal temp so I drove it around for 20 mins and it was fine. I parked it and went back out an hour later to check on it and it is overheating again and no cabin heat. I felt the radiator hose on bottom and it was cool enough to hold on to. So I checked the top hose and it was extremely hot. Like the thermostat was closed and no flow. Am I dealing with a thermostat issue or air in the system? Or could it be a leaking head gasket? Oil is clean no signs of coolant. Coolant is normal no signs of oil. Exhaust is normal etc. Where should I start on this engine?

 

You may have a seized thermostat, however filling the G with coolant is a time consuming process and most folks rush it and end up trapping a LOT of air in the system. Starting with a drained system, on the heater core hose there is a bleeder valve near the firewall, it's plastic so be careful they're notorious for breaking. If it does then you can order a nice metal one from Z1 Motorsports here:
https://www.z1motorsports.com/coolin...e-p-11190.html

I prefer the front of the car up on jackstands because the angle helps get more air out while filling.

With the bleed valve cap removed you need to add coolant SLOWLY, that's where most mistakes are made, you cannot just start dumping coolant into this car, 1 gallon per minute MAX and slower is better so air has a better chance of getting out. Once coolant starts to overflow out of the bleed valve reinstall the cap and finish adding coolant to the radiator until full.

If you jacked up the car take it back down to the ground now.

Next, turn the engine on, set the heater on MAX HOT with MAX FANSPEED so the heater core is fully opened, as the engine is warming up I like to rev the engine quite a few times up to the 3-5k range. If you're LUCKY the thermostat opens and flushes air out of the system, I've never had luck massaging the lower radiator hose but other folks have so ymmv. If it begins to slightly overheat turn it back off and place a fan in front of the car to cool it down quickly. Once cool check coolant levels again, turn the engine back on and go for a short drive (take coolant with you, you're going to need it if it does burp), be aggressive with the rpm's but make sure you are able to get back to shop without overheating. Might have to repeat a couple times.

You'll know when it burps, it's a very loud gurgling sound, add more coolant immediately when it does burp. Folks have had great success with the Lisle funnel that screws onto the radiator, I've never used one however and if you add the coolant SLOWLY while initially filling you shouldn't have problems. Seriously though it takes me about 5 minutes to do the initial fill so don't be in a rush unless you have a Lisle funnel handy.

If the thermostat is stuck though then none of this will work, personally I'd drain the system and start over fresh if it was my car.

 

 

 

 

Did you check the hoses again and squeeze them as it idles? You can rent a block tester from an auto parts store for like 20 bucks. It's a chemical test that you stick on the radiator and suck in air and it changes colors if there is exhaust gas present.

 

 

Sounds to me like you still have air in the lines. Are you making sure to have the heat turned all the way to high, and the fan speed turned all the way to high? You'll know when it finally does burp because it gurgles VERY loudly.

Also to post video's it's a lot better to upload to youtube and put the link in chat, the video will automatically embed.

 

 

I'd take it back to the dealership that sold it to you and tell them to do something about it since they likely KNOWINGLY sold you a vehicle with a bad head gasket.

 

If you do end up doing the engine swap make sure you buy the correct engine, there are a few variants of the VQ35DE that all share the same block name, you need an engine from a G/FX/350Z 2003-2007 AT (except 2007 350Z/G35 which I think switched to the HR motor) or 2003-2004 6MT. Look up the differences between the "rev-up" engine and the normal one. Also you cannot use the VQ35DE from a Maxima/Altima or any other transverse mounted one. I THINK you can use the engine from a 2006-2007 M35 but I can't remember.

 

Yeah that's class action lawsuit material right there if they don't do something about it.

 

 

When you say additive do you mean like stop leak or something? If he put that in then he damn well knew about the HG problem and is a POS. I'd also swap out your radiator and try flushing the heater core out just in case, since who knows if he even did it right. Sucks man...

 

Do you know where the guy lives? If somebody pulled something like that on me and they didn't know who I was you could bet I'd say some stuff over the phone which might cause him to sleep less well at night for a couple weeks.... maybe pay a homeless guy $20 to dump all the oil and coolants from the blown engine on his front porch or something like that...