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Once again the Sentra has got me scratching my head. I pulled my dipstick to check my level and it was at the same level as I had left it, nice and clean too, but it smelled very much like gas. I don't want to mess up my bearings or anything so any advice helps.

Couldn't find anything similar on here but other sites have said that the fuel smell could be due to running stupid rich or low compression. I checked the compression and its all good, around 175 PSI on all 4 which is awesome. At WOT I run in the high tens for my AFR around 10.8 consistently. I know that 10.8 is quite rich but that's the way Joe tuned it and it has been okay until now. I changed my oil about 1000kms ago, (600 miles?) and it already smells like gas. I will be sending a sample into Blackstone labs this week but was curious if this has happened to anyone and if you guys have any advice for me.

Thanks in advance guys!
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It could just be the type of type of oil you're running...My first guess would be rings, but with compression that high, it doesn't sound like it. I'm interested to find out what the lab says.
 

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Thanks for the response man. I'm using 10W30 Mobil 1 so I hope it's not the oil. I'll be rushing the sample so hopefully I'll have an answer on whether to be concerned or not soon.

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Joe tuned it? Is it turbo? If it's NA that's pretty freaking rich for a NA tune.

If it's turbo..........
What is your PCV/Breather setup?
 

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Joe tuned it? Is it turbo? If it's NA that's pretty freaking rich for a NA tune.

If it's turbo..........
What is your PCV/Breather setup?
He tuned it remotely through uprev. It is turbo and has the PCV and breather drilled out according to Joes instructions. Not sure what's up haha

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He tuned it remotely through uprev. It is turbo and has the PCV and breather drilled out according to Joes instructions. Not sure what's up haha

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Ok....turbo ;)
Makes a huge difference

Your PCV and Breather are run to where? Atmosphere, vented catch can, catch can connected to your turbo inlet? Where's everything run?
 

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Ok....turbo ;)
Makes a huge difference

Your PCV and Breather are run to where? Atmosphere, vented catch can, catch can connected to your turbo inlet? Where's everything run?
I'm running a catch can from the breather to the turbo inlet currently

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I'm running a catch can from the breather to the turbo inlet currently

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Is there anything in it?
And what about the PCV, where does it go?
 

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I'm asking all these questions because a properly functioning vent system is what removes gas and water and other funk from your oil.
 

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I am vented straight to atmosphere and don't have a can. I vent to the ground lol :shhh:. I haven't noticed any gas smell in my oil. But I change the oil about every thousand miles (only put 2k a year on the car) and I don't do any short drives in the car.


If there's gas in your oil, and your compression is good, I would "assume" you're doing short drives in the car where the oil doesn't get fully warmed up so that water and gas become vapor again and can escape, or maybe your catch can is full. Something along those lines.


Water will naturally get into your crankcase by means of condensation. From the engine getting hot and cooling off. Gas can also get in there, even with good compression. And when the engine is cool it also condenses back to a liquid. You need to get your oil up to operating temperature to turn those fluids back into vapor so they will vent.

Check your catch can and see if it's full. That would cause a venting issue.

Go for a long drive. Long enough to fully warm up your engine oil. At least 15-20 minutes. And then smell your oil again.





@shanover have any additional opinion or advice?
 
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Also worth mentioning I have an open dump wastegate, no cat, and along with venting crankcase to atmosphere... I'm kinda used to smelling gas.

Possible I wouldn't notice my oil smelling like gas. My car smells like gas already lol.

Your setup, if properly set up, should be better than mine. NEITHER is as good as stock. But we can't set it up like stock.
 

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I am vented straight to atmosphere and don't have a can. I vent to the ground lol :shhh:. I haven't noticed any gas smell in my oil. But I change the oil about every thousand miles (only put 2k a year on the car) and I don't do any short drives in the car.


If there's gas in your oil, and your compression is good, I would "assume" you're doing short drives in the car where the oil doesn't get fully warmed up so that water and gas become vapor again and can escape, or maybe your catch can is full. Something along those lines.


Water will naturally get into your crankcase by means of condensation. From the engine getting hot and cooling off. Gas can also get in there, even with good compression. And when the engine is cool it also condenses back to a liquid. You need to get your oil up to operating temperature to turn those fluids back into vapor so they will vent.

Check your catch can and see if it's full. That would cause a venting issue.

Go for a long drive. Long enough to fully warm up your engine oil. At least 15-20 minutes. And then smell your oil again.





@shanover have any additional opinion or advice?
Shoot sorry forgot to say that the PCV goes to the catch can as well, Just t'd into breather/catch can hose. I was going to vent to atmosphere but I like to see if there is much being collected in the can just in case. Haven't noticed too much collecting between oil changes. I daily my car and usually do around 3k km intervals and race it every weekend. I'll take it for a good cruise tonight and see if there is a difference. Thanks for the input Dave, I appreciate it!

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I am vented straight to atmosphere and don't have a can. I vent to the ground lol :shhh:. I haven't noticed any gas smell in my oil. But I change the oil about every thousand miles (only put 2k a year on the car) and I don't do any short drives in the car.


If there's gas in your oil, and your compression is good, I would "assume" you're doing short drives in the car where the oil doesn't get fully warmed up so that water and gas become vapor again and can escape, or maybe your catch can is full. Something along those lines.


Water will naturally get into your crankcase by means of condensation. From the engine getting hot and cooling off. Gas can also get in there, even with good compression. And when the engine is cool it also condenses back to a liquid. You need to get your oil up to operating temperature to turn those fluids back into vapor so they will vent.

Check your catch can and see if it's full. That would cause a venting issue.

Go for a long drive. Long enough to fully warm up your engine oil. At least 15-20 minutes. And then smell your oil again.





@shanover have any additional opinion or advice?
Nope, you pretty much covered it as far as function and possibilities, Mine is piped into my turbo inlet pipe tho, and since I got the fancy heated catch can I have had zero water in my oil unless I only do a short warm up on a cool day. The heated can evaporates all the water to vapor, to be sucked into the intake just like a standard pcv setup is, except with less vacuum on the engine. as for oil smelling like gas, a couple of things come to mind. One, if you use standard oil, it will smell somewhat like gas, since they come from the same dead dinosaurs. Two, if you are on a factory stock tune, it usually runs pig rich all the time and this will allow more gas vapors from blowby. Three, exactly what dave said, drive the car until fully warmed up, say at least twenty miles once in a while so you can be sure to scavenge all the moisture and fuel vapors from the block. Atmosphere vented catch cans will have more of a tendency to let vapor build up, since there is really no vacuum on the system, and the only circulation is from the blowby pushing air out of the catch can. With my first catch can during the humid part of the year. most of the year down here, I had to empty and clean my catch can sometimes twice a week. it was a small mishimoto unit, the standard for 2J turbo builds, I could always tell when it got full, because I would get the pudding up into the turbo inlet. this also lead to oil getting on the maf, and boost stumbles while driving. Some fuel smell in the oil is to be expected, pistons never seal 100% and you will always get some blowby, fuel vapors especially on the compression stroke. I would say you probably have a normal situation going on, or are just very sensitive to the fuel smell. If it smelled like a cup full of gas, I'd worry, but if the oil is clean, and the oil fill cap doesnt have the water/oil pudding on it, I doubt you have a problem.

besides, what are you doing smelling your oil to check for problems??? you are supposed to TASTE IT!
 

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Also, just to add: running turbo, where you are packing much more air and fuel into the cylinders, you will get a proportionately higher level of blow by from the intake charge. This is another reason for a cool down period especially after driving hard. the excess blowby will not all vent from the block and into the can, much of the fuel mist will be mixed with the oil. Again, a nice, easy drive, for a few miles once the engine is up to temperature, will go a long way to scavenging the vapors and moisture from the oil. I drive 30 miles on the interstate each way to work every day, much of the drive (about 1/3) is thru neighborhoods and small towns. Since I put the heated can on, I have had zero problems, and am even considering hooking the can drain so that I can pipe it back into the block. the only thing I have gotten out of the heated can, is clean, fresh looking oil.
 

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Discussion Starter #16
Interesting, maybe I need to invest in a better catch can then haha. I realize that with turbo there will be added pressures in the cylinders but I hadn't noticed this issue until recently. Last night I took the car out for a good drive and the oil smelled more like oil. Probably all the shorter trips I've been making lately then. Thanks for the input guys! Learning something new everyday! @yogib @shanover

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