Recent Topics
injecter cleaner?
by ernied - 12/12/19 09:27 AM
Which would you use for 5k
by Bettez88 - 12/12/19 09:08 AM
Effective ways to reduce humidity inside the car
by MoneyJohn - 12/12/19 08:21 AM
Stupid regulations- Diesel Cap Color
by Rmay635703 - 12/12/19 08:20 AM
Help a not-so-noob: shear stability theory.
by OilStasher - 12/12/19 08:03 AM
Latest oil purchase for Lawnmowers
by Snagglefoot - 12/12/19 07:44 AM
Old school bra
by whizbyu - 12/12/19 07:10 AM
Tricky flight ticket change fees
by Superflan - 12/12/19 07:10 AM
2019 Jeep Rubicon F&R Axle UOAs [5,000 Miles]
by 2015_PSD - 12/12/19 06:58 AM
Redline SL-1. Application warning
by BMWTurboDzl - 12/12/19 06:51 AM
My Forester CVT blew up
by IMPALA08 - 12/12/19 06:30 AM
2016 Titan XD Cummins, Schaeffers 9000 5W-40
by 06_lx - 12/12/19 06:09 AM
Will moving steering via wheel hubs cause harm?
by mobilaltima - 12/12/19 12:26 AM
This oil looks interesting but not avail in US
by jkhawaii - 12/11/19 10:39 PM
Castrol Engine Shampoo (Oil Flush)
by adams355 - 12/11/19 10:03 PM
How Dumb can she get #2
by KeithS_NW_Ohio - 12/11/19 09:45 PM
Dodge Transmission
by Butterbean - 12/11/19 09:38 PM
Pay Raise
by KeithS_NW_Ohio - 12/11/19 09:17 PM
Newest Members
lutvi20, Bazik, Lamasuna, berlinbai, SimpleGuy48
70111 Registered Users
Who's Online Now
109 registered members (2010Civic, adams355, 2015_PSD, 928, Alfred_B, 1foxracing, 7 invisible), 1,984 guests, and 22 spiders.
Key: Admin, Global Mod, Mod
Forum Statistics
Forums67
Topics298,621
Posts5,139,304
Members70,111
Most Online3,589
Nov 2nd, 2019
Donate to BITOG
Print Thread
Hop To
Oil flow and Vehicle start with oil cap off. #5138985 06/20/19 05:49 AM
Joined: Apr 2010
Posts: 4,322
B
BMWTurboDzl Offline OP
OP Offline
B
Joined: Apr 2010
Posts: 4,322
(deleted)

Last edited by BMWTurboDzl; 06/20/19 06:05 AM.

“It took untold generations to get you where you are. A little gratitude might be in order. If you’re going to insist on bending the world to your way, you better have your reasons.”

435i
Re: Oil flow and Vehicle start with oil cap off. [Re: BMWTurboDzl] #5138993 06/20/19 06:04 AM
Joined: Nov 2008
Posts: 14,920
S
supton Online Content
Online Content
S
Joined: Nov 2008
Posts: 14,920
I wouldn't think so... When one piston is going down (causing positive pressure) one is going up (negative pressure) so I don't think there is a net change in airflow in the engine. [At least when there is an even number of pistons, err at least in most conventional automotive engines.]
Likewise, when the engine lifts oil up and fills the galleries, the oil level drops in the pan.

Ultimately there is a ventilation system for the crankcase. This is to deal with blowby that is created while running.

Lastly, whenever I have removed the filler cap while running I've always had some amount of oil spray coming out and all over. Not a geyser mind you just enough to realize it's making a mess. Maybe that was just on the mills I've dealt with, maybe a BMW has better baffles.

In this case I don't think it will matter at all if you are just priming it, but that's my wild guess of the morning. Will be curious what the BMW mechanics have to say.


2011 Toyota Camry, base, 2.5L/6MT, 196k, hers
2010 Toyota Tundra DC, 4.6L/6AT, 155k, ours
1999 Toyota Camry LE, 2.2L/4AT, 217k, his
Re: Oil flow and Vehicle start with oil cap off. [Re: BMWTurboDzl] #5138998 06/20/19 06:09 AM
Joined: Dec 2002
Posts: 43,409
S
Shannow Offline
Offline
S
Joined: Dec 2002
Posts: 43,409
Missed the OP...but read the second...

The swept volume of an automotive cylinder is not a pure sinusoidal volume change.

For exactly the same reasons that you can't balance a 4 cylinder, there is a significant change in crankcase volume every 90 degrees, and a change in pressure...leave the oil cap off a running 4 cylinder and have a look...

And there's not enough to change any sort of priming mechanism post oil change.


If it's the truth....it can handle the pressure !!!
Re: Oil flow and Vehicle start with oil cap off. [Re: Shannow] #5139003 06/20/19 06:19 AM
Joined: Apr 2010
Posts: 4,322
B
BMWTurboDzl Offline OP
OP Offline
B
Joined: Apr 2010
Posts: 4,322
Originally Posted by supton
I wouldn't think so... When one piston is going down (causing positive pressure) one is going up (negative pressure) so I don't think there is a net change in airflow in the engine. [At least when there is an even number of pistons, err at least in most conventional automotive engines.]
Likewise, when the engine lifts oil up and fills the galleries, the oil level drops in the pan.

Ultimately there is a ventilation system for the crankcase. This is to deal with blowby that is created while running.

Lastly, whenever I have removed the filler cap while running I've always had some amount of oil spray coming out and all over. Not a geyser mind you just enough to realize it's making a mess. Maybe that was just on the mills I've dealt with, maybe a BMW has better baffles.

In this case I don't think it will matter at all if you are just priming it, but that's my wild guess of the morning. Will be curious what the BMW mechanics have to say.



Originally Posted by Shannow
Missed the OP...but read the second...

The swept volume of an automotive cylinder is not a pure sinusoidal volume change.

For exactly the same reasons that you can't balance a 4 cylinder, there is a significant change in crankcase volume every 90 degrees, and a change in pressure...leave the oil cap off a running 4 cylinder and have a look...

And there's not enough to change any sort of priming mechanism post oil change.






Thanks for the replies. I deleted it because I figured it wasn't thread worthy and somewhat of a stupid question.

Shannow: Here is the SIB I had originally mentioned.

SIB


“It took untold generations to get you where you are. A little gratitude might be in order. If you’re going to insist on bending the world to your way, you better have your reasons.”

435i
Re: Oil flow and Vehicle start with oil cap off. [Re: Shannow] #5139004 06/20/19 06:19 AM
Joined: Nov 2008
Posts: 14,920
S
supton Online Content
Online Content
S
Joined: Nov 2008
Posts: 14,920
Originally Posted by Shannow
Missed the OP...but read the second...

The swept volume of an automotive cylinder is not a pure sinusoidal volume change.

For exactly the same reasons that you can't balance a 4 cylinder, there is a significant change in crankcase volume every 90 degrees, and a change in pressure...leave the oil cap off a running 4 cylinder and have a look...

I stand corrected then.

I have pulled the cap off my 4 bangers and figured that airflow was just air into the engine... hmm.


2011 Toyota Camry, base, 2.5L/6MT, 196k, hers
2010 Toyota Tundra DC, 4.6L/6AT, 155k, ours
1999 Toyota Camry LE, 2.2L/4AT, 217k, his
Re: Oil flow and Vehicle start with oil cap off. [Re: BMWTurboDzl] #5139064 06/20/19 07:45 AM
Joined: Apr 2018
Posts: 564
T
talest Offline
Offline
T
Joined: Apr 2018
Posts: 564
You should feel air sucking IN and not pushing OUT is this correct

Re: Oil flow and Vehicle start with oil cap off. [Re: talest] #5139075 06/20/19 08:10 AM
Joined: Dec 2005
Posts: 12,908
K
kschachn Online Content
Online Content
K
Joined: Dec 2005
Posts: 12,908
Originally Posted by talest
You should feel air sucking IN and not pushing OUT is this correct

It can be both, the pistons displace air in the crankcase as well as the cylinder.


1994 BMW 530i, 251K
1996 Honda Accord, 280K
1999 Toyota Sienna, 428K
2000 Toyota ECHO, 284K
Re: Oil flow and Vehicle start with oil cap off. [Re: BMWTurboDzl] #5139811 06/21/19 02:27 AM
Joined: Mar 2013
Posts: 945
W
weasley Offline
Offline
W
Joined: Mar 2013
Posts: 945
Don't forget the effect of blow-by, which positively pressurises the crankcase and is the reason a PCV is needed. If you run an engine with the cap off, the crankcase won't pressurise and you will get a flow of blow-by gases out of the oil filler.


2017 SEAT Leon 1.4 EcoTSI 150 FR Technology DSG
2018 Volvo XC60 D4
2011 KTM 990 SMT
Re: Oil flow and Vehicle start with oil cap off. [Re: BMWTurboDzl] #5139813 06/21/19 02:59 AM
Joined: Mar 2015
Posts: 7,214
B
bbhero Offline
Offline
B
Joined: Mar 2015
Posts: 7,214
I did this lovely little feat the other week by accident LOL


I was impressed how quiet my motor was running with the cap off.


Nissan Altima 3.5 Coupe
Napa full synthetic 5w30 Wix 57356 Oil filter
"Treat your family like your friends and treat your friends like your family."
Re: Oil flow and Vehicle start with oil cap off. [Re: BMWTurboDzl] #5139815 06/21/19 03:04 AM
Joined: Mar 2015
Posts: 7,214
B
bbhero Offline
Offline
B
Joined: Mar 2015
Posts: 7,214
Not a stupid question at all...

There's zero doubt in my mind that you are very smart.

We all have areas where we don't know everything about everything... And asking questions is how we learn new things.


Nissan Altima 3.5 Coupe
Napa full synthetic 5w30 Wix 57356 Oil filter
"Treat your family like your friends and treat your friends like your family."
Previous Thread
Index
Next Thread

BOB IS THE OIL GUY® Powered by UBB.threads™