350zoverheated

Background: 06 350Z MT 113k Miles. Its always had a slight oil consumption problem, but seems to have gotten worse over the years. About 2 years ago it overheated on me while going down the highway. Hauled to shop, replaced Tstat and radiator, problem solved. About 3 weeks ago I got caught behind a wreck idling for a long period of time and looked at my dash to notice SES light and pegged temp gauge. Pulled over, checked oil and noticed it was bone dry. Walked to store, filled back up with oil, and continued to work with no incidence. I figured the low oil meant more friction = overheat. A few days later it does it to me again, but the oil level is fine.

So I park it for a few days then try to recreate the problem in my driveway by idling for a long time and notice the fans aren't coming on, even with the AC turned on. Once the the temp gauge begins exceeding the normal level (~40%) the engine suddenly kicks up a notch and white smokes begins pouring out the exhaust. Also I'm getting no cabin heat, it just blows cool (not a huge problem since I'm in Texas).

So I bought new fans and just installed them. Fans come on properly now, and I haven't been able to recreate the overheating, but it still begins to whitesmoke once its been idling at operating temp for 15+ mins. And maybe its just my imagination, but the engine just doesn't feel the same.

My first impressions on the whole ordeal was head gasket, so I bought a leak test kit and ran it twice. Both came back negative, though I'm not 100% sure I did it properly. I left the radiator cap off and turned the car on a let it idle for a good 20mins or so to get to normal running temp, used a syringe to keep running the coolant level down enough to fit the plunger, then ran the test. However, during the test I wasn't experiencing the whitesmoke problem. Should I let it run longer and test it again while whitesmoking? Is it okay to just leave the radiator cap off that long and keep removing coolant as it heats up to fit the plunger in?

On the other hand I suppose the smoking could be an unrelated fuel/air issue, but it doesn't smell too rich/lean.

Any thoughts or similar experiences welcome.

Updated: Tried running extensive leak tests today, even during the whitesmoking and they've all come back negative. Basically I cranked the engine with the radiator cap off and used a syringe to remove coolant from the neck as the engine warmed up. Eventually the fans kick on, the engine revs up a tiny amount, and I asssume the Tstat opens since the coolant level suddenly drops down the neck. Around this time the whitesmoking first starts. I've done the leak test 10 times, both with the T-stat open (coolant level dropped in the neck, fans engaged due to temp sensor) and closed (coolant is expanding up neck, using syringe to drop level to fit plunger without sucking up coolant). I've noticed some light smoke coming out of the neck, but I assume this to just be steam from the coolant reaching high temps.

Not really sure what to think. It's not overheating on me since replacing the fans, but the whitesmoking has only been there since it last overheated. I don't want to keep driving it if the smoking is indicative of a major problem.

Spike100

Engine coolant leaking into the cylinders can cause the white exhaust you noticed. That might indicate a warped head.

travlee

iTrader: (8)

i am just amazed that you have a model that is known for oil consumption and you don't religiously check it.... especially since you stated it was "bone dry" when was the last time you actually checked or changed it