mjc1055

So last month, I picked up an 06 350z with just shy of 40k on the clock. Runs and drives perfectly, and is completely stock (for now) other than a Nismo CAI.

So the people who owned it before me were the original owners, and were a little older. The car sat at the dealership for awhile before I picked it up, and then sat in my garage for a few weeks while I was out of town for the holidays.

I've started driving it again this week, and when I took 2nd gear all the way to the redline, I checked my mirror and noticed a cloud of white smoke behind me. I know white smoke typically means coolant. Later in the night, I did this again, but no white smoke this time. I also ran the car up near the redline a few times the day I bought it, and didn't notice any smoke. Additionally, my coolant level is still right at the "max" mark on the reservoir. I don't see any stains on the ground where I park my car, and I don't see any crusty coolant around the heads (although the engine bay is freakin packed and it's hard to see much).

I've been a Honda and Subaru guy up until now, so this is my first Nissan/VQ experience. I couldn't come up with anything like this by searching. Has anybody ever experienced white smoke, but (very) intermittently? Is this possibly the result of the car having sat a lot recently?

Any help is appreciated!

davidv

iTrader: (2)

White smoke may also be the result of fuel injector problems.

suprasam

I had white smoke once but because the crankcase pressure blew out my dipstick. The oil was "evaporated" on the exhaust manifolds but everything else was okay. Big scare though. I'm boosted too and not sure if any NA guys are having issues with excess crankcase pressure.

mjc1055

Interesting, yeah my roommates old DSM used to blow the dipstick out all the time, scared the **** out of us the first time it happened. I hit WOT a few more times this morning to see if I could reproduce (terrible idea, I know) and nothing, even going all the way to 6800 RPM +.

Also, I thought fuel smoke was usually black?

suprasam

oil when heat not by fire will burn bluish white. if a turbo seal is leaking oil into the turbine housing then you get the white smoke. my mk3 supra had the turbo seals go and it was like a smoke machine from spy hunter

mjc1055

interesting.

at any rate, i havent been able to make the car do it again, so i'm thinking it may have either been condensation in the exhaust (although there was a fair amount of smoke) or possibly the car just dumping too much fuel up top, given that the car has probably rarely (if ever) revved that high, and certainly not in a long time. guess i wont worry about it for now, but something to keep an eye on.

mjc1055

So my car has done this a couple of times now... if I hold the RPMs around 3k-ish and then punch it, sometimes it will blow a moderate amount of white smoke out of the exhaust, but only briefly. As the RPM's climb, no more smoke comes out after the initial amount. Subsequent gears won't smoke, either, after shifting and continuing to push the car.

The car burns almost no oil (1500 miles in, still about 85% full on the dipstick), but I have noticed a very slight consumption of coolant. I say consumption because the car doesn't leak anything.

Anyway, is this a very early sign of headgasket failure, maybe? The temp needle says my car doesn't run hot, and my oil doesn't look milky. I've had it since 39,000 miles, it's at 45,000 now and still runs and behaves perfectly fine. Just drove it on a thousand mile roundtrip and it was great.

Waiz

iTrader: (57)

You made a thread for this same issue before?

https://my350z.com/forum/maintenance...only-once.html

Did you not get it looked at then?

SparkleCityHop

iTrader: (30)

Threads merged

Waiz

iTrader: (57)

Good work Hop!

mjc1055

sorry for creating a second thread.. i wanted to update the OP with the additional info and bump it with a new post, but for some reason i can't edit that first post anymore.

Anyway, updated info in the thread now so hopefully somebody has some input for me! Thanks.

mjc1055

bump for great justice! is a (very) slow loss of coolant from the expansion tank at all normal? I can't imagine that it would be.

Another thing is that awhile back while checking the oil, I noticed that there was what looked like a small amount of coolant sitting in one of the bolt hole recesses on top of the intake manifold. I wonder if I somehow managed to blow coolant up and out of the expansion tank, unless it could have gotten there some other way?

Neimad

There are test strips to put in the coolant and detect combustion gasses. Coolant is in a sealed system, doesnt lose much unless its boiling over and the cap releases pressure.

mjc1055

can you buy these at any autoparts store? assuming that the strip turned up positive for combustion gasses, would that generally be indicative of a headgasket failure or is there another point of entry for those kinds of materials?

Neimad

I never needed them, not sure. I can usually tell by other means. Definately would be headgasket though. A friend just went through this on civic. They verified by doing a leakdown test. Introducing compressed air when the piston is at TDC and everything should be sealed.

mjc1055

Out of curiosity, is it possible to burn up coolant that doesn't involve the headgasket, if the car isn't leaking anything? Possibly something to do with either the intake manifold, or lines running near the intake manifold?

Just seeing if there's anything common before I go and pay for a leakdown test. I found some time coolant on top of the manifold in one of the bolt recesses awhile back, wondering if that could be connected.

Neimad

There is a coolant circuit that warms the throttle body, two small hoses. It should be practically impossible for this to get into the intake.

When the engine is at full warm, use a rag and try to squeeze the upper radiator hose. If it is hot and non-squeezeable the system is sealed pretty well. If you can squeeze the hose either the cap is bad or you have a leak. Coolant has a particular smell, I can usually tell there is a leak without opening the hood.

mjc1055

it's definitely not leaking onto the ground, and my exhaust doesn't smell sweet. the coolant i found near the intake manifold was actually on top, in a few of the little recesses were you bolt down the upper intake manifold.

i guess maybe the leakdown is the only way to go. i get some spark knock as well, so i'm wondering if its possibly a small headgasket leak thats causing coolant to get into the combustion chamber and lower the effective octane of my fuel. the coolant reservoir is just dropping very, very slowly.