G35 Running Hot At heavy speeds

The G-Series Tuning Forum is the place to discuss G35/G37 performance modifications and mechanical repair.
imcraig2
Posts: 5
Joined: Mon Mar 12, 2018 9:55 am
Car: 2008 infinity g35

G35 Running Hot At heavy speeds

Postby imcraig2 » Sat May 12, 2018 9:14 am

First of all I just want to say thank you to everyone for this forum and to the people with similar problems. Because of this site and the manuals (no longer exist) i was able to complete a full water pump, thermostat, and other coolant issues with ease. Now on to the other issue.
After doing basically a complete coolant fix pump, thermo, coolant etc, the car after about a week started to run hot at heavy speeds 70+. the fans are kicking on especially when i use the AC, but seem to be working harder as the temp climes. After about a week of driving i had to add about a half gallon of coolant (no Leaks). The resevoir is empty when it gets that hot and you can hear it bubbling but after it cools down it fills up to the proper line. Hoses are not stiff so i know the thermo is working right. This only seems to happen like i said under heavy load. The fans seem a little louder then normal as well. I did use the special funnel to get the air pockets out and was good for about a week. Now its starting to act up and i cant figure it out. could the fans not be working properly and are there any sensors associated with them?
Any help would be great.
2008 G35 coupe with the pain in the a** engine to change a water pump on.


macgiver
Posts: 629
Joined: Wed Jul 04, 2007 10:21 am

Re: G35 Running Hot At heavy speeds

Postby macgiver » Sat May 12, 2018 9:33 am

mac, the forum I'm sure appreciates you too . On this - the "reservoir empty when hot...& filling back up when cold" seems opposite , and more importantly is the "bubbling" . Now all your work was for a "cooling system fault" ?, and come back - reply with a little more history on that - w/pump ? Leak?froze thermo? hose? coolant from block's "weep hole" ? etc. And IF you OVERHEATED AT ALL ? Hate to say , early here , but seems consistant with bown head gasket, and bubbles are high-pressure exhaust blowing into cooling system , then overcoming radiator cap & blowing bubbles into overflow? But I hope not.

tjrob2000
Posts: 55
Joined: Sat Jun 07, 2014 5:42 pm
Car: 2007 G35 sedan (journey)

Re: G35 Running Hot At heavy speeds

Postby tjrob2000 » Sun May 13, 2018 3:40 pm

Agree with macgiver here, need more info. If you're getting bubbling in the res then you have a serious issue. The res should show higher level hot than cold as the coolant expands. I'm not sure what to make of the opposite happening. It sounds like your coolant is getting sucked in somewhere then when it cools it releases back to the system, but I don't know how that could be. If you have a blown head gasket you'll see it in the oil. It will look milky on the dip stick.

imcraig2
Posts: 5
Joined: Mon Mar 12, 2018 9:55 am
Car: 2008 infinity g35

Re: G35 Running Hot At heavy speeds

Postby imcraig2 » Tue May 15, 2018 7:43 am

Thank guys. The car had a faulty water pump leaking through the weep hole. I replaced all other parts, hoses thermo etc, as a precautionary measure. Car never fully overheated. The head gasket does not seem to be blown, no oil in water and no water on the dipstick. Still very clean and clear from the oil change when I changed everything. Bubbles are more in the hose.

imcraig2
Posts: 5
Joined: Mon Mar 12, 2018 9:55 am
Car: 2008 infinity g35

Re: G35 Running Hot At heavy speeds

Postby imcraig2 » Tue May 15, 2018 7:45 am

macgiver wrote:
Sat May 12, 2018 9:33 am
mac, the forum I'm sure appreciates you too . On this - the "reservoir empty when hot...& filling back up when cold" seems opposite , and more importantly is the "bubbling" . Now all your work was for a "cooling system fault" ?, and come back - reply with a little more history on that - w/pump ? Leak?froze thermo? hose? coolant from block's "weep hole" ? etc. And IF you OVERHEATED AT ALL ? Hate to say , early here , but seems consistant with bown head gasket, and bubbles are high-pressure exhaust blowing into cooling system , then overcoming radiator cap & blowing bubbles into overflow? But I hope not.
Thank guys. The car had a faulty water pump leaking through the weep hole. I replaced all other parts, hoses thermo etc, as a precautionary measure. Car never fully overheated. The head gasket does not seem to be blown, no oil in water and no water on the dipstick. Still very clean and clear from the oil change when I changed everything. Bubbles are more in the hose.

imcraig2
Posts: 5
Joined: Mon Mar 12, 2018 9:55 am
Car: 2008 infinity g35

Re: G35 Running Hot At heavy speeds

Postby imcraig2 » Tue May 15, 2018 7:48 am

tjrob2000 wrote:
Sun May 13, 2018 3:40 pm
Agree with macgiver here, need more info. If you're getting bubbling in the res then you have a serious issue. The res should show higher level hot than cold as the coolant expands. I'm not sure what to make of the opposite happening. It sounds like your coolant is getting sucked in somewhere then when it cools it releases back to the system, but I don't know how that could be. If you have a blown head gasket you'll see it in the oil. It will look milky on the dip stick.
Thank guys. The car had a faulty water pump leaking through the weep hole. I replaced all other parts, hoses thermo etc, as a precautionary measure. Car never fully overheated. The head gasket does not seem to be blown, no oil in water and no water on the dipstick. Still very clean and clear from the oil change when I changed everything. Bubbles are more in the hose.

macgiver
Posts: 629
Joined: Wed Jul 04, 2007 10:21 am

Re: G35 Running Hot At heavy speeds

Postby macgiver » Tue May 15, 2018 8:34 am

mac, then that's one big huge air-pocket floating around the heads?? Keep in mind ,thoeretically possible,for the high pressure combustion gases to blow through gasket "ring" migrate the head/block surface,pushing into the "water-jacket" and bubbling out into overflow jug.Coolant-oil may NOT mix in any discernable amount , or AT ALL. This scenario may of course have coolant , under the 12 lb pressure "migrate' into cylinder's chamber. PLUG CHECK may show evidence of this , which is otherwise hidden, "under the radar"! :lolling:


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