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Oh no...

5K views 17 replies 9 participants last post by  NoWhining 
#1 · (Edited)
My heart skipped a beat this morning when I drove my '01 Xterra (3.3L) out to go on a hike.

I drove it about 5-10 min or so, parked, looked out my rear view mirror, and what do I see? A tad bit of white vapor coming from the tailpipe. The first thing that popped in my head was... head gasket...

So got out, walked around back and watched the tail pipe for a bit... just a little bit of what looked like water vapor coming out. I revved the car a bit, and it didn't get any more intense, it just stayed about the same. I then got in, drove for a bit longer, came back, and the vapor/smoke was gone. I let it sit a bit longer there idling and then the tailpipe started to drip water (it was dry immediately after I got back from the drive).

I looked under the hood, checked the coolant reservoir - not brown, milky or bubbling; it was green. Looked at the oil dipstick - it looked totally normal. Looked at the oil cap - looked normal too. Engine seems to be running fine.

I haven't driven it around long enough to see if the coolant level is dropping, but I will be doing that. It doesn't appear to be though based on the two times I checked. The car has never been overheated, and the engine is never raced.

So the only things I can come up with are: Excess water in the exhaust turning to steam, water in my fuel tank, or the head gasket. I brought up the first two options because I frequently leave my Xterra parked for long periods of time between drives (~usually a week). I've had the same gas in the tank for over 2 months now.

Any ideas would be welcome! I'm at a fork in the road on whether or not to take a hit and get it fixed, or buy a new car. Thanks!
 
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#2 ·
Water vapor from the exhaust is pretty normal, especially when it is cold and humid outside. I would say if its below about 40 degrees out my x has water dripping from the exhaust. its not always something wrong with the truck, under certain circumstances it is normal.
 
#5 ·
Yeah it is very normal. If you dont believe us watch it everyday. All cars will have white vapor upon start up. When the combustion process happens N, H2o, and Co2. If you look at your exhaust after it starts up you will always see water leaving the tail pipe. That is why they have Weep holes in mufflers. Overnight the internals of the engine "sweat" and that condensation gets burned out upon initial start as well as H2o is a continuous creation from all 6 of your cylinders. The white smoke should disappear within 8-10 minutes. If it does not and it warms up with white smoke then you know you have a problem.
 
#6 ·
Also ethanol in modern gas is an anhydrous form of ethanol that has a very low water content in it. When the fuel sits for any period of time, it will pull moisture out of the air and into the gas. This can also cause you to see some water vapor from the exhaust. It will also make your vehicle run like crap if your truck sets for long periods of time without running.
 
#7 · (Edited)
Yeah it is very normal. If you dont believe us watch it everyday. All cars will have white vapor upon start up. When the combustion process happens N, H2o, and Co2. If you look at your exhaust after it starts up you will always see water leaving the tail pipe. That is why they have Weep holes in mufflers. Overnight the internals of the engine "sweat" and that condensation gets burned out upon initial start as well as H2o is a continuous creation from all 6 of your cylinders. The white smoke should disappear within 8-10 minutes. If it does not and it warms up with white smoke then you know you have a problem.
Define "warms up"...

When I think of warmed up, the coolant temp gauge is in its normal steady position.

I've seen other people say warmed up is when you drive it for a while (~15 min or so) since the exhaust system lags behind the engine getting up to temperature.

Anyway, it was still steaming a bit when the engine was warm. Not big large puffs, but little stream of vapor and water dripping out. However, after I took it for a drive, and parked again, it was gone. I revved the engine a bit and let it sit and idle for about 5 minutes. No steam.

Then I turned it off, came back about an hour and a half later, started it up, let it sit for about 2 minutes and there was just a little bit of steam coming out.

We'll see I guess. I was driving around yesterday in our other car and noticed other people's tailpipes steaming at about the same rate... and it was roughly the same temp and humidity out. I'm only concerned because when the coolant temp needle was at its normal position, it was still steaming a bit... but the drive seemed to make it go away.

Sorry if I'm blowing this out of proportion here.
 
#8 · (Edited)
Well, I'm beginning to feel like there really is a problem with it.

I started it up again today (around 62 degrees, 40% humidity). Let it idle about 20 minutes until the temperature gauge was in the middle. Truck was running fine, no missing or roughness. However, water was dripping (about 1 every two seconds) out of the tailpipe and there was about a 4 inch radius puddle underneath it.

I got in, brought the engine RPMs up a little, and sure enough, a little bit of steam came out with splatters of water. The steam was very hard to see, as there wasn't a lot of it, but the water seemed excessive given the weather outside. Strangely, coolant level seems stable and there doesn't appear to be any bubbling in the reservoir.... however, I do notice a bit of a coolant smell in the engine compartment.

At this point, I'm going to take it in on Monday to have it checked out. Unfortunately I live about 90 miles from a Nissan dealer, so I'll probably have a local place look at it. If it is in fact the gasket, what should I roughly expect to pay? Is it common to have both head gaskets replaced while they are working on it?

Thanks guys. You've all been great!
 
#9 ·
Everything you have mention is normal for around here in western North Carolina. Even in the low to mid 60's. If you want to try, take a plate,plastic bag or anything that you can put under your tail pipe in the morning and let the engine idle. You should only catch clear water with soot. If you have a internal coolant loss you will see what ever color of antifreeze you are running along with soot. At most take it and have the coolant system pressured tested to give yourself a little piece of mind. After my 2004 set for 3 weeks and I started it up it was dripping from the muffler and the tail pipe and that was in a 60degree shop.
 
#11 ·
Given the right temperature and humidity, it can blow steam indefinitely. I was in stop and go traffic for about an hour after skiing a few weeks ago and every single car was putting off a good amount the whole time.
 
#12 ·
Haha, you guys are killing me here. :D

dyna105, I'll give your bag trick a shot tomorrow morning. After your truck sat for 3 weeks, did it keep dripping water out even after it was warmed up?

I'll keep you guys up to date! Thanks all.
 
#13 · (Edited)
Bad radiator cap.

That was the diagnosis from the shop. They said the steam and water were perfectly normal and everything checked out ok. They did a pressure test and chemical test on the coolant system.

Apparently the coolant smell I was getting from the engine compartment was due to a bad seal between the radiator cap and radiator.

Dodged a bullet there! Thanks guys for the help. You all helped keep my sanity in check while waiting for the official word. :D
 
#14 ·
Glad to hear you got out on the cheap. It did keep dripping till the exhaust system completely heated up. Which is a while longer than the engine heating up. This was inside the shop the whole time. I think what had you going was the loss of coolant with the smell.Than you found the tailpipe dripping.
 
#15 · (Edited)
that water in the exhaust comes not just from the combustion process...but due to the humidity in the air...

typically...the exhaust systems metal will be colder than the ambient air...even at warmer temperatures...the ambient air is combusted...and cooled as it travels down the exhaust pipes. As air cools...it has less ability to hold water in it (as a humid vapor). So the warmer combusted air can travel with water vaporized in the form of humidity...and as it cools, it can't hold as much water in vapor state...so it condenses out of the air and turns to water in the exhaust.

So it depends not just on temperature of the ambient air...but also on the humidity...and also on the temperature of the exhaust system...and also the heat transfer coefficient of how much heat/temperature is lost in the exhaust gas as it travels through the system!

It is the same way you get water droplets on the outside of a glass of ice water...the ice and water doesn't physically travel through the glass...the ice water cools the glass material enough that the air right next to it cools too! The ambient air in the room is warm enough to hold enough vapor in gas form...but the air cools right next to the glass and the vapor water changes phase into water drops on the cold glass!

Another long winded answer by rob!
 
#16 ·
Glad to hear you got out on the cheap. It did keep dripping till the exhaust system completely heated up. Which is a while longer than the engine heating up. This was inside the shop the whole time. I think what had you going was the loss of coolant with the smell.Than you found the tailpipe dripping.
Yeah what got me was that it was still dripping water even after I let it idle and warm up for 20 minutes. What I didn't consider though is the difference between the engine being warm and the exhaust system being warm... I always thought everything was good to go and hot once the temperature needle was in the middle.

Not really the case... the exhaust system kinda lags a bit behind the engine. So it really does take a good 15-20 min drive to get the exhaust system completely hot. After that, no steaming or dripping.
 
#17 ·
Everybody makes that assumption which is why nobody believes experienced techs when they tell them they are harsh drivers. Anything under a 20 minute drive is technically harsh on the vehicle. The coolant does not indicate a warmed up vehicle. It takes a long time for the exhaust and the Oil inside the engine to warm up compared to the coolant. It only takes roughly 7 Minutes for the coolant to reach temperature but it takes like 15 for the oil and about 20 for the full exhaust to warm up. It also depends on temperature obviously.
 
#18 ·
Ryan, you indeed dodged a bullet there... I'm not so fortunate.

My X stopped (or slowed) the dripping of water from the A/C unit. Then the A/C wouldn't work for a while or only when I 'tapped' the compressor with a tire iron.

Last bill is over $2100 and I still don't have it back yet. :(
Driving a POS rental car.
 
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