I broke something

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Freise
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I broke something

Post by Freise »

So this little problem has been around for months.
When I let the car idle for periods of time, it will begin bellowing white smoke. There is absolutely no pattern! It goes away if I drive. If I rev it in neutral, it blows smoke, but if I put the engine under load the smoke disappears and only reappears after some time idling. The time from idle to smoking is also completely random. My first obvious thought was, I blew my headgasket. However, there have been no signs in 3 oil changes. I've had no coolant loss. The smoke does not smell sweet in any way, but rather like badly burnt metal.
In this video, car had been run up to operating temperature. The smoking begins rather quickly, about 30 seconds after coming to idle.
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I've tried to capture this on video for a while now, but sometimes it can take anywhere from 5-10 minutes before any kind of smoke.

Any ideas? Compression tests in the past came back passing, like I said, this problem has been plaguing me for months.
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Post by iceman1357 »

well looks like oil. so valve stem seals come to mind. they can act odd as they go ie. slowly rotating in place around the valve. bad PCV or a little to much oil in the system?
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TheOne
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Post by TheOne »

possibly valve stem seals like above. compression test is not gonna reflect that. , leak down test might not even reflect that.
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Post by boostedPOS »

I had the same thing as you in my single cam. When i first got my car it would bellow white smoke at idle only after the car was completely warm. I did a compression check and every single cylinder was 160. So i didn't think it was my headgasket, All my plugs were the same colors and my exhaust didn't smell sweet either. I figured it was somehting else and i kept fixing other stuff on my car. Until a month ago my car would stumble when i would start it when it was already warmed up. It would stumble for only a couple seconds then drive fine. Then about a week ago all hell broke loose and it would barely run and billowed out white smoke that was sweet smelling. Headgasket was blown. I took off my head and found that cyclinder #4 had some cracks in the headgasket and burn marks. I think i lifted my head a lil from boost and when my car would warm up it would suck coolant into the cyclinder at idle because that is when it has the most vacuum.

i would warm up the car and get it to repeat this smoke, then to a leak down test and see if there is air in your coolant. You can take your radiator cap off and see if it bubbles. I hope this has helped you. Good luck finding out what it is!.
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Post by nissanfanatic »

Seems like a turbo oil seal to me...
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Post by emo_tactical9 »

nissanfanatic wrote:Seems like a turbo oil seal to me...
That's what-if thought to. Low turbo speeds with an old journal bearing turbo could cause some leaking.
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Post by nissanfanatic »

I think it just takes some time for the exhaust to heat up and start burning the oil. A good check may be to start the car for a few moments and then disconnect the downpipe. Check and see if there is oil. You may also be able to find some in the charge pipe if oil is also leaking past the compressor seals. Plus, the compressor side is much easier to check.
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Post by Freise »

I was possibly thinking oil seals in the turbo as well. Although I have no experience with the inner workings of the head, if the valve seals were bad, would they not go bad somewhat randomly? In other words, wouldn't one or two go bad at first, causing a sort of "puffing" affect? This is like a constant stream of smoke, as if each cylinder was burning off a high volume of oil. Is this thinking correct? Or would all the seals give out simultaneously?
After taking that video yesterday, I shut the car off during that smoking. Later on, I started her up and just let it idle for about 20 minutes. She started right up, no smoke. It began smoking about 10 minutes in for about a minute, then just quit. Then began smoking again about 5 minutes later, again for a minute or two, and then quit again. This was all purely at idle, no throttle at all. Not sure if that helps at all.

In the meantime I'm going to check the piping and downpipe and will report back if I find anything. Thanks guys, I appreciate it.
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Post by nissanfanatic »

Well if it is the turbo oil seals, it should leak horribly once RPM is above idle due to an increase in oil pressure. It would also get worse as oil temps increase due to a decrease in oil viscosity.
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Post by Freise »

nissanfanatic wrote:Well if it is the turbo oil seals, it should leak horribly once RPM is above idle due to an increase in oil pressure. It would also get worse as oil temps increase due to a decrease in oil viscosity.
Ok, so because it's only leaking at idle, that's evidence against turbo oil seal, and evidence for valve stem seals or something else?

I just got done going through the intercooler piping, no signs of oil, the piping is dry and clean. Going to take a look at the downpipe tomorrow.
Thanks again,
-Tim
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Post by boostedPOS »

You can also check your headers for oil residue. That can help verify if it is valve seals.
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Post by Freise »

I jacked up the car, and removed the testpipe before removing the downpipe (my downpipe is a huge pita to remove), let her warm up and idle for more than 30 minutes, and couldn't get it to smoke at all. There was no oil or reside present in the downpipe at all. It was also about ~75* today, which means the car got a chance to warm up to its full 180*, so I assume the oil would have reached its thinnest viscosity during this time, and therefore provided it's highest chance for leaking, either past valve seals or turbo seal. Any ideas?
I had an idea, the oil drain for the turbo runs right over the driver side engine mount and the arm near the front suspension, would it be possible that it is occasionally getting kinked, and oil is backing up forcing it past turbo oil seal, but as the suspension moves (as I drive) it is unkinking and then functioning correctly? It's a long shot and an oddly specific theory, but I'm sort of running out of ideas. Any help or further testing ideas are welcome.
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Post by nissanfanatic »

Oil backing up in the return line could certainly cause that type of issue.

With checking the downpipe, I think it is more important to check it after only a few seconds of idling. If the downpipe gets hot, it will just burn any oil off.

If the issue is gone, I would just leave everything alone until it happens again.
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Post by Silviadream87 »

What is your oil return line made out of? I had a problem with mine from previous owner, used a cheap hose and just from heat or suction or what not it would suck the hose closed, blocking off oil and sending it threw the turbo seals.

I got a more sturdy hose and have never had the problem since
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Post by sicks13 »

I had the exact problem with my old car.. It was the turbo seals leaking, the majority of the smoking was due to the oil entering the engine from the compressor side of the turbo! it takes a very small amount of oil to create smoke!! pull your intercooler pipe off at its lowest point, when i did this i had half a quart of oil in mine!
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Post by ATLspeed »

as stated...turbo oil seal.
- pull the turbo off and inspect the exhaust wheel. If there is sign of oil then pow there ya go.

if not

- then check the exhaust ports for oil
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Post by emo_tactical9 »

Turbo seals typically don't go bad. If it is a ****, abused old turbo then it is possible. Blowing massive amounts of oil through the turbo doesn't mean the seals are bad, more likely it is the drain causing issues.
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Post by sicks13 »

emo_tactical9 wrote:Turbo seals typically don't go bad. If it is a ****, abused old turbo then it is possible. Blowing massive amounts of oil through the turbo doesn't mean the seals are bad, more likely it is the drain causing issues.


The seals do go bad! do you know what seals the turbine side? its a piston ring with a end gap of somewhere between .0015" and .0040". They will collapse over time or with high heat and cause oil to leak out.. On the compressor side you have the same situation, piston rings seal the flinger sleeve to the insert and a o-ring seals the insert to the bearing housing, over time or with excessive heat the o-ring will become brittle and the piston rings can collapse...


I do agree that most smoke issues are caused by oil drain issue. A turbo with some mileage will have shaft play, this shaft play puts stress on the piston rings; the extra heat caused by this will collapse the piston rings!

Just my 2 cents
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Post by Freise »

Oil drain is made from rubber or silicon hose, it's very thick... but not solid.
I don't think my seal is bad since the problem is very intermittent. In fact, the more i think about it (and with everyone's opinion), the more I could see the drain line causing the issue more than anything else.
I have gone through most of my IC piping including the lowest point on the hot side and no signs of oil at all, so I don't believe compressor side is leaking.
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