VQ35DE oil burjning issue - step inside
08-15-2005, 10:08 PM
#1
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VQ35DE oil burjning issue - step inside
OKay guys, been doing research on this, apparently the VQ35 motor is an oil burner.
I thought mine was a unique case. My dealer had an 04 VQ35 Maxima in as well, and its eating up oil.
I went to teh 350z boards and they are also complaining of oil burning.
If this is the case, the VQ35 SUX @SS.
Mine is still buring 1L per 1000-1500kms. My fuel economy is shot to hell, average about 300kms per tank mixed. And at todays gas prices, i am quite fed up.
My car is going in for the 10th time to the dealer on thursday to discuss this matter.
I been addiing oil time and time again (almost like every 5th fill up of gas, i add 1L)
I think i am going to stop filling this POS motor with oil and let the fukkker run dry and let this VQ35 motor die ....
Anybody else with this issue, step inside, i wnana know how yours has been resolved.
This is not an isolated incidient, there are very many reported cases of VQ35 oil burning issues.
I thought mine was a unique case. My dealer had an 04 VQ35 Maxima in as well, and its eating up oil.
I went to teh 350z boards and they are also complaining of oil burning.
If this is the case, the VQ35 SUX @SS.
Mine is still buring 1L per 1000-1500kms. My fuel economy is shot to hell, average about 300kms per tank mixed. And at todays gas prices, i am quite fed up.
My car is going in for the 10th time to the dealer on thursday to discuss this matter.
I been addiing oil time and time again (almost like every 5th fill up of gas, i add 1L)
I think i am going to stop filling this POS motor with oil and let the fukkker run dry and let this VQ35 motor die ....
Anybody else with this issue, step inside, i wnana know how yours has been resolved.
This is not an isolated incidient, there are very many reported cases of VQ35 oil burning issues.
08-16-2005, 06:15 AM
#5
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I need some info like what oil are you using and how many kms driven. Amsoil S2K 0w-30? If so, you might consider using their S3K 5w-30 which is thicker with a better additive package and diesel rated. It is the same price as the premium S2K.
If you would like to save a few $$$, consider trying the Esso XD3 0w-30; I have seen some good used oil analysis reports from this oil. It is widely available in Canada (Esso bulk dealers, I believe?) and inexpensive but unfortunately not available in the US.
If this fails, do some research on http://www.auto-rx.com/
If you would like to save a few $$$, consider trying the Esso XD3 0w-30; I have seen some good used oil analysis reports from this oil. It is widely available in Canada (Esso bulk dealers, I believe?) and inexpensive but unfortunately not available in the US.
If this fails, do some research on http://www.auto-rx.com/
08-16-2005, 06:21 AM
#7
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Originally Posted by johnny2kgle
I need some info like what oil are you using and how many kms driven. Amsoil S2K 0w-30? If so, you might consider using their S3K 5w-30 which is thicker with a better additive package and diesel rated. It is the same price as the premium S2K.
If you would like to save a few $$$, consider trying the Esso XD3 0w-30; I have seen some good used oil analysis reports from this oil. It is widely available in Canada (Esso bulk dealers, I believe?) and inexpensive but unfortunately not available in the US.
If this fails, do some research on http://www.auto-rx.com/
If you would like to save a few $$$, consider trying the Esso XD3 0w-30; I have seen some good used oil analysis reports from this oil. It is widely available in Canada (Esso bulk dealers, I believe?) and inexpensive but unfortunately not available in the US.
If this fails, do some research on http://www.auto-rx.com/
Yes what he said. ... You might be using to light of an oil, try a thicker weight. 10w-30 i use in my car . Amsoil all the way! 
I use 1 quart a month, doing 70 miles round trip everyday,my car has 110,000 mile on her and she runs strong as a bull.
08-16-2005, 06:26 AM
#8
Originally Posted by MiniRX7
OKay guys, been doing research on this, apparently the VQ35 motor is an oil burner.
I thought mine was a unique case. My dealer had an 04 VQ35 Maxima in as well, and its eating up oil.
I went to teh 350z boards and they are also complaining of oil burning.
If this is the case, the VQ35 SUX @SS.
Mine is still buring 1L per 1000-1500kms. My fuel economy is shot to hell, average about 300kms per tank mixed. And at todays gas prices, i am quite fed up.
My car is going in for the 10th time to the dealer on thursday to discuss this matter.
I been addiing oil time and time again (almost like every 5th fill up of gas, i add 1L)
I think i am going to stop filling this POS motor with oil and let the fukkker run dry and let this VQ35 motor die ....
Anybody else with this issue, step inside, i wnana know how yours has been resolved.
This is not an isolated incidient, there are very many reported cases of VQ35 oil burning issues.
I thought mine was a unique case. My dealer had an 04 VQ35 Maxima in as well, and its eating up oil.
I went to teh 350z boards and they are also complaining of oil burning.
If this is the case, the VQ35 SUX @SS.
Mine is still buring 1L per 1000-1500kms. My fuel economy is shot to hell, average about 300kms per tank mixed. And at todays gas prices, i am quite fed up.
My car is going in for the 10th time to the dealer on thursday to discuss this matter.
I been addiing oil time and time again (almost like every 5th fill up of gas, i add 1L)
I think i am going to stop filling this POS motor with oil and let the fukkker run dry and let this VQ35 motor die ....
Anybody else with this issue, step inside, i wnana know how yours has been resolved.
This is not an isolated incidient, there are very many reported cases of VQ35 oil burning issues.
You are cursed. I feel sorry for you.
And FYI, my car doesn't burn oil, at least nothing beyond the normal 1/2 qt. per 5k miles-ish.
And in your case I wonder if most of the oil is going through your crankcase vent instead of leaking past the oil rings.
08-16-2005, 01:54 PM
#11
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I think i am going to stop filling this POS motor with oil and let the fukkker run dry and let this VQ35 motor die ....
If you have a warranty left you can chance it...
My motor uses about a 1/4 quart every 1000. I have heard that higher miles 3.5s eat it up like mad. I am finishing up an Auto-RX and most likely switching to synthetic oil to **hopefully** slow/stop comsumption.
BTW, if you are using 0W30 oil, that could be some of you problem. I would step up to 10W or a 5W40 and see what happens.
08-16-2005, 02:31 PM
#16
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I agree with what the others said, the fact that you use a 0w30 oil can have a lot to do with it. I guess the only way to really find out is find some members you use that type of oil and see if they have similair issues and then compare other members who use regular 10w30.
08-16-2005, 02:40 PM
#17
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Get rid of the SAE 00W-30 ASAP particularly with the MT. Try a 10W-30 for about a 1000k and report back. DO NOT run her dry. Even dealers or Nissan Canada ain't that stupid! Why the 00w-30 anyway?? I hope you weren't suckered in?
08-16-2005, 02:53 PM
#19
Um why would the 0w-30 be any diff than 5w or 10w?? The engine/oil is only cold for a short amount of the total time it's used. Thus the oil is only acting like a 0w for a very short time. It's not the oil.
If it's as SR said, though the crankcase breather, take the hose off. If it's that much, that tubing should be soaked with oil.
I suggest in addition to the above:
1) Take a sample of the oil and get it analyzed by Blackstone
2) Get a compression check done and a leakdown.
If it's as SR said, though the crankcase breather, take the hose off. If it's that much, that tubing should be soaked with oil.
I suggest in addition to the above:
1) Take a sample of the oil and get it analyzed by Blackstone
2) Get a compression check done and a leakdown.
08-16-2005, 03:29 PM
#20
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That repeated "short period of time" at 00 or close to it and with the MT especially, is all it would take in my opinion to possibly cause some wear issues here, plus, depending if the guy allows for much of a warmup "go easy" period or has somewhat of a "lead" foot, these may also be part of the problem. And you "can't beat viscosity" if you want to cut oil consumption anyway, even with today's oils. Even BMW will not recommend anything less than a 5W in their cars. The M3 has a requirement of a 10W-60. Checking the crankcase vent or intake manifold for oil is a waste of time. It will be there in all cars, particularly with the MT.
08-16-2005, 03:30 PM
#21
I never broke my engine in like they said you should and I don't see any oil consumption on my 123K mile Maxima. I was redlining her all the time from the day I bought it. I don't think engine break in has anything to do with it, look at the QR25DE motors, they burn oil regardless if the engine was babbied for the 1st 5K miles or ran hard.
I would stop wasting $$$ on Synthetic if it burns it, put some 10W30 GTX Castrol in it and see if it burns it. If it still happens, let her blow up and get a new motor.
I would stop wasting $$$ on Synthetic if it burns it, put some 10W30 GTX Castrol in it and see if it burns it. If it still happens, let her blow up and get a new motor.
08-16-2005, 03:33 PM
#22
Unless this person only drives 3 miles at a time, it's not really the oil. Because an ave person's cold drive time is only about 10% of the whole session.
Yes, there WILL be oil in the vent/intake. That's part of the design. But if that much oil is being lost on those areas, it will have WAY MORE then what is normal. Puddles of it. Should be quite obvious if he's losing excessive oil though those systems. Please examine my original post clearly.
Yes, there WILL be oil in the vent/intake. That's part of the design. But if that much oil is being lost on those areas, it will have WAY MORE then what is normal. Puddles of it. Should be quite obvious if he's losing excessive oil though those systems. Please examine my original post clearly.
Originally Posted by P. Samson
That repeated "short period of time" at 00 or close to it and with the MT especially, is all it would take in my opinion to possibly cause some wear issues here, plus, depending if the guy allows for much of a warmup "go easy" period or has somewhat of a "lead" foot, these may also be part of the problem. And you "can't beat viscosity" if you want to cut oil consumption anyway, even with today's oils. Even BMW will not recommend anything less than a 5W in their cars. The M3 has a requirement of a 10W-60. Checking the crankcase vent or intake manifold for oil is a waste of time. It will be there in all cars, particularly with the MT.
08-16-2005, 03:35 PM
#23
If you take it to your dealership and tell them what's happening, they should do a leak test (run it for 1,000 miles or whatever you Canadan's equate it to) with a dye in it. If it's not leaking out the block, it's being burning and Nissan will replace it. They replace them all the time in the 350 Z's and other VQ35 based cars.
08-17-2005, 03:27 PM
#24
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Could your Frankencar intake be the reason you have apparent high oil consumption? Above idle and when there is vacuum in the intake manifold, breather vapors are sucked out of the crankcase from the rear camshaft cover into the intake manifold at the PCV Valve. The fresh filtered air supply (the vent) comes from that odd looking black plastic box or plenum attached to the intake duct between the MAF and TB. But..... crankcase breather vapors will backflow through the crankcase vent hose into the intake upstream of the TB, at or near WOT because at the same time of course vacuum approaches zip in the intake manifold and the PCV Valve line cannot flow any breather vapors. This also of course is the time when breather vapors are at the max. due to max. blowby gases being added to the volume. The Frankencar design (just looking at the photo mind you) with the crankcase vent adapter tube attached to the sidewall could be acting like a flow inducer (jet pump). The Nissan stock design has the PCV vent originating at the side of that black plastic plenum and is nowhere near the flow (and the flow inducing) of the intake air. I'm wondering if even at midrange throttle openings could there be enough airflow in the intake to induce enough suction in that Franckencar vent tube to pull breather vapors into the intake? This vent line I.D. is a lot bigger than the PCV line and with an increase in throttle opening and corresponding drop in vacuum particularly approaching the 3/4 to full throttle, and I'm thinking could this be causing more than normal breather vapors getting into the intake upstream of the TB. For the science of it try disconnecting the vent hose at your intake, start the car and put a piece of paper close to the vent adaptor tube (unless you somehow have a vacuum gauge calibrated in In. of H2O!!) and see if the paper gets sucked to the end of the tube as you increase engine speed. (I just did this on my '00 stock vent connection up to about 3000 rpm with no signs of suction there.)
08-17-2005, 03:38 PM
#25
Originally Posted by E55AMG2
Its not that common actually....
08-17-2005, 05:45 PM
#30
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Originally Posted by P. Samson
Could your Frankencar intake be the reason you have apparent high oil consumption? Above idle and when there is vacuum in the intake manifold, breather vapors are sucked out of the crankcase from the rear camshaft cover into the intake manifold at the PCV Valve. The fresh filtered air supply (the vent) comes from that odd looking black plastic box or plenum attached to the intake duct between the MAF and TB. But..... crankcase breather vapors will backflow through the crankcase vent hose into the intake upstream of the TB, at or near WOT because at the same time of course vacuum approaches zip in the intake manifold and the PCV Valve line cannot flow any breather vapors. This also of course is the time when breather vapors are at the max. due to max. blowby gases being added to the volume. The Frankencar design (just looking at the photo mind you) with the crankcase vent adapter tube attached to the sidewall could be acting like a flow inducer (jet pump). The Nissan stock design has the PCV vent originating at the side of that black plastic plenum and is nowhere near the flow (and the flow inducing) of the intake air. I'm wondering if even at midrange throttle openings could there be enough airflow in the intake to induce enough suction in that Franckencar vent tube to pull breather vapors into the intake? This vent line I.D. is a lot bigger than the PCV line and with an increase in throttle opening and corresponding drop in vacuum particularly approaching the 3/4 to full throttle, and I'm thinking could this be causing more than normal breather vapors getting into the intake upstream of the TB. For the science of it try disconnecting the vent hose at your intake, start the car and put a piece of paper close to the vent adaptor tube (unless you somehow have a vacuum gauge calibrated in In. of H2O!!) and see if the paper gets sucked to the end of the tube as you increase engine speed. (I just did this on my '00 stock vent connection up to about 3000 rpm with no signs of suction there.)
PCV valve internal spring backseats the valve when pressure is equalized, as long as its working properly, there shouldnt be any oil coming through that tube.
08-18-2005, 12:17 AM
#31
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Actually i probably used 0w30 for like 15,000kms or so (in the winter)
Now for the past 15,000 i been using 5w30 conventional because its such waste of money to keep on adding synthetics to oil disappear.
No blue smoke, the dealership even replaced teh seals, however I am meeting them tommorrow (new clutch, pressureplate under warranty as the clutch sticks to the floor and makes crunchy noises) and I will neeed to discuss it.
I am no longer adding anymore oil. The dealer service manager said he would replace the motor, but having problems with NA NISSAN head office getting it.
This is a common VQ35DE probelm, as it was posted on the 350z boards on a thread as well as several org members exhibiting burning oil, or oil lose.
My dads 2000 E320 was also consuming the same, and had the motor replaced under warranty.. I hope they will replace mine.
Now there is new rattling noises getting louder and louder.. Sounds like the end of my VQ35DE!
SR20DET here i come LOL
Yes i had bad luck with this 2k3 after 60KM
Now for the past 15,000 i been using 5w30 conventional because its such waste of money to keep on adding synthetics to oil disappear.
No blue smoke, the dealership even replaced teh seals, however I am meeting them tommorrow (new clutch, pressureplate under warranty as the clutch sticks to the floor and makes crunchy noises) and I will neeed to discuss it.
I am no longer adding anymore oil. The dealer service manager said he would replace the motor, but having problems with NA NISSAN head office getting it.
This is a common VQ35DE probelm, as it was posted on the 350z boards on a thread as well as several org members exhibiting burning oil, or oil lose.
My dads 2000 E320 was also consuming the same, and had the motor replaced under warranty.. I hope they will replace mine.
Now there is new rattling noises getting louder and louder.. Sounds like the end of my VQ35DE!
SR20DET here i come LOL
Yes i had bad luck with this 2k3 after 60KM
08-18-2005, 12:23 AM
#32
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Originally Posted by BewstAdd1ct
PCV valve internal spring backseats the valve when pressure is equalized, as long as its working properly, there shouldnt be any oil coming through that tube.
08-18-2005, 08:20 AM
#33
I must have the engine in the worst shape here... 33k and burning MORE than 1q/1k miles. *****ed at Regal Nissan, Nissan Consumer Affairs, etc. I have used mobil 1 5w30 since 5k miles, changed every 3-4k, using nissan or pureone filters. I did not notice the problem until 31k when I heard a loud "ticking" noise under my hood, took the car to Regal 3 days later and found out there was only 1qt of oil remaining in my engine. I have been keeping an oil consumption log for the dealer but they said I will need very good luck for the suits at Nissan NA to grant me a new engine.
note: also checked my PCV valve, it is operating correctly
note: also checked my PCV valve, it is operating correctly
08-18-2005, 03:35 PM
#34
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Originally Posted by P. Samson
I guess I didn't make myself clear. I'm talking about the breather vapors (which do contain suspended oil particles) BACKFLOWING via the PCV VENT hose/line at the intake duct UPSTREAM of the TB (between the TB and the MAF).
i know exactly what youre talking about. you arent understanding how a PCV valve works, though.
the manifold vacuum has to great enough to overcome the spring pressure in teh PCV valve and the crankcase vacuum.
if theres a vacuum at the case vent, YES I FOLLOW YOU, BETWEEN THE MAF AND T/B-- THE FRESH AIR INLET and youre at WOT (0" vacuum) then you will be backseating the PCV valve.
and even without a vacuum created by the intake pipe, at WOT pressure IS equalized, at least enough to close the PCV valve.
PCV flow happens the most during cruise...
08-18-2005, 04:46 PM
#35
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Originally Posted by madmxx
I must have the engine in the worst shape here... 33k and burning MORE than 1q/1k miles. *****ed at Regal Nissan, Nissan Consumer Affairs, etc. I have used mobil 1 5w30 since 5k miles, changed every 3-4k, using nissan or pureone filters. I did not notice the problem until 31k when I heard a loud "ticking" noise under my hood, took the car to Regal 3 days later and found out there was only 1qt of oil remaining in my engine. I have been keeping an oil consumption log for the dealer but they said I will need very good luck for the suits at Nissan NA to grant me a new engine.
note: also checked my PCV valve, it is operating correctly
note: also checked my PCV valve, it is operating correctly
My god, if thats the case, i guess i will need to seek the adivce of a legal advisor, if i find out they dont approve.
08-18-2005, 05:16 PM
#36
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i seriously dont think hell have a problem getting a new engine... the only thing is, if he has a consumption log, then he know there was a problem and should have stayed on top of his oil level. its the owners responsibility.
however, its hes got documented complaints of the issue beforehand, its should be fairly easy.
however, its hes got documented complaints of the issue beforehand, its should be fairly easy.
08-18-2005, 06:37 PM
#37
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The PCV valve that I have in my possession is going to flow all the time except at WOT like you suggest. It takes very little vacuum to unseat the valve against the very light spring pressure and it will flow at idle vacuum and it seems to be unrestricted and it physically cannot "seat" in the "vacuum" direction. At 0 vacuum it does seat or tries to seat, agreed. It would not take much pressure differential to unseat it though. With the engine running at or near 0 vacuum (WOT) the breather vapors are going to backflow through the vent into the intake duct between the MAF and TB gumming up the TB like we see. I do not agree that the crankcase pressure will ever be negative as long as the vent system is clear, obviously. (thus the "normal" PCV flow) You wouldn't want the crankcase to even "try" to have a vacuum..... you would have seal issues and oil leaks etc. I learned today from a dealer that HOC problems like MiniRX7's have been addressed by Nissan Canada by replacing VQ35 engines on several occasions up here on the West Coast alone. I couldn't get details on the root cause (or fix) etc. Intake plenums are removed by the dealers and are found loaded with oil.
08-18-2005, 06:47 PM
#38
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Originally Posted by P. Samson
The PCV valve that I have in my possession is going to flow all the time except at WOT like you suggest. It takes very little vacuum to unseat the valve against the very light spring pressure and it will flow at idle vacuum and it seems to be unrestricted and it physically cannot "seat" in the "vacuum" direction. At 0 vacuum it does seat or tries to seat, agreed. It would not take much pressure differential to unseat it though.
With the engine running at or near 0 vacuum (WOT) the breather vapors are going to backflow through the vent into the intake duct between the MAF and TB gumming up the TB like we see.
I do not agree that the crankcase pressure will ever be negative as long as the vent system is clear, obviously. (thus the "normal" PCV flow)
You wouldn't want the crankcase to even "try" to have a vacuum..... you would have seal issues and oil leaks etc.
I learned today from a dealer that HOC problems like MiniRX7's have been addressed by Nissan Canada by replacing VQ35 engines on several occasions up here on the West Coast alone. I couldn't get details on the root cause (or fix) etc. Intake plenums are removed by the dealers and are found loaded with oil.
08-18-2005, 07:49 PM
#39
Originally Posted by BewstAdd1ct
i seriously dont think hell have a problem getting a new engine... the only thing is, if he has a consumption log, then he know there was a problem and should have stayed on top of his oil level. its the owners responsibility.
however, its hes got documented complaints of the issue beforehand, its should be fairly easy.
however, its hes got documented complaints of the issue beforehand, its should be fairly easy.
08-19-2005, 05:53 AM
#40
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Originally Posted by BewstAdd1ct
agreed, agreed, and agreed.
like oyu see? take a look again. if thats the case, then why is there rarely oil residue on the front of the throttle plate, only the back and the edge?
I have seen lots of engines with oil residue (skunge) on the upstream side of the whole damn TB. The bore, throttle plate and IAC passages. Sometimes the throttle sticks slightly on opening. On some there is very little crud. There is always at least some oily film though. The front face of the throttle plate is getting impinged by air, particularly at the smaller throttle openings and maybe it gets somewhat "scrubbed" of oil which gets pushed, even at idle, downstream past the sliver of a gap between the closed throttle and the bore. After shutdown oil is going to "wick" to the throttle plate edge if there is oil in the TB bore from any source. Also, some cars have an intake manifold or intake plenum design where the PCV Valve tube is quite close to the TB so any oil after shutdown may migrate back to the TB and throttle. My previous V6 did that. The "floor" of the plenum was flat. Conversely, doesn't the VQ35 have the TB a heck of a long way from the PCV Valve tube outlet?. Oil is sometimes seen on the lower edge of the stock air filter and puddled in the convolutes of the intake flex ducting, usually on MT cars that tend to get "punched" a lot. Being "punched" is only going to be a relatively short duration event but over a period of driving time it adds up. There is no question about the breather backflowing via the vent into the inlet duct and that the breather at times may contain oil droplets. well if its as you suggest, the vent hose recieving a vacuum, then during WOT, assuming minimal blowby with the PCV valve closed there would be a slight vacuum.
At WOT there is no way there can be a vacuum in the crankcase. Anyway I was ONLY talking about the non stock Frankencar intake design possibly (my question/theory) inducing enough air flow at the vent adaptor tube where it is welded to the duct, creating a small drop in pressure and possibly adding to the volume of breather backflowing into the intake duct. This flow inducing action could only develop vacuum measured in In. of H2O. Very low in other words. I'm not talking suction in In. of Hg. Anyway, since finding out that some VQ35s do seem to have real HOC issues this is N/A. why not, it aids in ring seating and boosing compression. a vacuum if anything would keep oil from seeping and certainly wouldnt be strong enough to suck a gasket/seal in.
Would not work. Can't happen. Would have been done. Think about the philosophy of the crank seals etc. And if it wasn't much of a vacuum anyway it wouldn't do anything for compression. Involves re-engineering. Every 4 stroke internal combustion engine I know of will have a crankcase/breather pressure of above ambient.
oil residue (and sometimes oil in liquid form) reaches the I/M normally, something with moderate ring sealing issues could throw liquid into the i/m without a problem. the question would be, was there large amounts of liquid oil in the intake pipe?
like oyu see? take a look again. if thats the case, then why is there rarely oil residue on the front of the throttle plate, only the back and the edge?
I have seen lots of engines with oil residue (skunge) on the upstream side of the whole damn TB. The bore, throttle plate and IAC passages. Sometimes the throttle sticks slightly on opening. On some there is very little crud. There is always at least some oily film though. The front face of the throttle plate is getting impinged by air, particularly at the smaller throttle openings and maybe it gets somewhat "scrubbed" of oil which gets pushed, even at idle, downstream past the sliver of a gap between the closed throttle and the bore. After shutdown oil is going to "wick" to the throttle plate edge if there is oil in the TB bore from any source. Also, some cars have an intake manifold or intake plenum design where the PCV Valve tube is quite close to the TB so any oil after shutdown may migrate back to the TB and throttle. My previous V6 did that. The "floor" of the plenum was flat. Conversely, doesn't the VQ35 have the TB a heck of a long way from the PCV Valve tube outlet?. Oil is sometimes seen on the lower edge of the stock air filter and puddled in the convolutes of the intake flex ducting, usually on MT cars that tend to get "punched" a lot. Being "punched" is only going to be a relatively short duration event but over a period of driving time it adds up. There is no question about the breather backflowing via the vent into the inlet duct and that the breather at times may contain oil droplets. well if its as you suggest, the vent hose recieving a vacuum, then during WOT, assuming minimal blowby with the PCV valve closed there would be a slight vacuum.
At WOT there is no way there can be a vacuum in the crankcase. Anyway I was ONLY talking about the non stock Frankencar intake design possibly (my question/theory) inducing enough air flow at the vent adaptor tube where it is welded to the duct, creating a small drop in pressure and possibly adding to the volume of breather backflowing into the intake duct. This flow inducing action could only develop vacuum measured in In. of H2O. Very low in other words. I'm not talking suction in In. of Hg. Anyway, since finding out that some VQ35s do seem to have real HOC issues this is N/A. why not, it aids in ring seating and boosing compression. a vacuum if anything would keep oil from seeping and certainly wouldnt be strong enough to suck a gasket/seal in.
Would not work. Can't happen. Would have been done. Think about the philosophy of the crank seals etc. And if it wasn't much of a vacuum anyway it wouldn't do anything for compression. Involves re-engineering. Every 4 stroke internal combustion engine I know of will have a crankcase/breather pressure of above ambient.
oil residue (and sometimes oil in liquid form) reaches the I/M normally, something with moderate ring sealing issues could throw liquid into the i/m without a problem. the question would be, was there large amounts of liquid oil in the intake pipe?