Does the crank case push pressure or pull a vaccume?, I did something stupid.... |
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Does the crank case push pressure or pull a vaccume?, I did something stupid.... |
VaccaRabite |
Aug 8 2021, 06:38 PM
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#1
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En Garde! Group: Admin Posts: 13,465 Joined: 15-December 03 From: Dallastown, PA Member No.: 1,435 Region Association: MidAtlantic Region |
So some of you may remember my thread a couple weeks back that the oil filler cap disappeared during a spirited drive a while back. I have 2 other caps, but they are the wrong size (grrrr).
I drove a couple times and not much oil came out, but a little did. So I figured some aluminum foil where the filler cap should be would keep the small amount of oil the comes out from happening. So after applying some heavy duty foil, I fired her up and went for a drive for about an hour. Came back and the FOIL WAS NOW GONE! There was foil around the lip of the filler, but the foil the covered the opening has either been blown off, or sucked into the crank case. So... yeahhhhhhhhhh. (IMG:style_emoticons/default/icon8.gif) (IMG:style_emoticons/default/stromberg.gif) (IMG:style_emoticons/default/slap.gif) Engine ran great. No changes to oil pressure or oil temps. Clearly I need to drain the oil out and also pull the tuna can off and look around. So. How boned am I? Zach |
BeatNavy |
Aug 8 2021, 06:44 PM
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#2
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Certified Professional Scapegoat Group: Members Posts: 2,924 Joined: 26-February 14 From: Easton, MD Member No.: 17,042 Region Association: MidAtlantic Region |
Zach, pretty sure intake is going to have vacuum (runners, manifold, throttle body, cylinders, etc.). The oil filler is part of the crank case. There you will have pressure from whatever blow-by you get. But hopefully not too much (or you'll have oil leaks everywhere).
Edit: point being, it most likely got blown off. |
wonkipop |
Aug 8 2021, 06:52 PM
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#3
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Advanced Member Group: Members Posts: 4,403 Joined: 6-May 20 From: north antarctica Member No.: 24,231 Region Association: NineFourteenerVille |
(IMG:style_emoticons/default/agree.gif)
most likely. there is vacuum but its at the valve, hose to air cleaner inlet plenum to help draw the vapours into the induction side of engine. better get yourself a new filler cap mate. |
Spoke |
Aug 8 2021, 06:54 PM
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#4
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Jerry Group: Members Posts: 6,992 Joined: 29-October 04 From: Allentown, PA Member No.: 3,031 Region Association: None |
I would think the crankcase would be under pressure unless you have vacuum from the intake connected to the PCV. If you have a catch tank and filter, the crankcase would be under pressure at all times.
For the tinfoil cap, if it blew off I would think it would be jammed in the fan and likely squished together along some of the vanes as centrifugal force would flatten the foil against the vanes. |
SirAndy |
Aug 8 2021, 07:00 PM
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#5
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Resident German Group: Admin Posts: 41,681 Joined: 21-January 03 From: Oakland, Kalifornia Member No.: 179 Region Association: Northern California |
Does the crank case push pressure or pull a vaccume? Both, depending on the rpm ... (IMG:style_emoticons/default/shades.gif) |
VaccaRabite |
Aug 8 2021, 08:01 PM
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#6
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En Garde! Group: Admin Posts: 13,465 Joined: 15-December 03 From: Dallastown, PA Member No.: 1,435 Region Association: MidAtlantic Region |
(IMG:style_emoticons/default/agree.gif) most likely. there is vacuum but its at the valve, hose to air cleaner inlet plenum to help draw the vapours into the induction side of engine. better get yourself a new filler cap mate. I've got 3, but they are all the wrong size. I think (as in I saw it recently) I have a whole other filler neck I can put on that uses the size cap that I have a surplus of. I just need to find it and swap it over. I'm still going to drain the oil and pull the tuna can just to inspect everything. But I tend to agree its probably sucked into the fan and blown over under the tins somewhere... Zach |
SirAndy |
Aug 8 2021, 08:55 PM
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#7
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Resident German Group: Admin Posts: 41,681 Joined: 21-January 03 From: Oakland, Kalifornia Member No.: 179 Region Association: Northern California |
Does the crank case push pressure or pull a vaccume? Both, depending on the rpm ... (IMG:style_emoticons/default/shades.gif) To elaborate, on my 2056 i used to blow out the plugs for the head vents. So i did some testing and at lower rpm <3k-ish the engine would suck in air through the head vents but above >3k-ish it would switch to blowing out air (and oil) from the same vents. (IMG:style_emoticons/default/idea.gif) |
Krieger |
Aug 8 2021, 11:26 PM
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#8
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Advanced Member Group: Members Posts: 4,729 Joined: 24-May 04 From: Santa Rosa CA Member No.: 2,104 Region Association: None |
Cut your oil filter open and give a look.
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wonkipop |
Aug 9 2021, 04:46 AM
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#9
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Advanced Member Group: Members Posts: 4,403 Joined: 6-May 20 From: north antarctica Member No.: 24,231 Region Association: NineFourteenerVille |
Does the crank case push pressure or pull a vaccume? Both, depending on the rpm ... (IMG:style_emoticons/default/shades.gif) To elaborate, on my 2056 i used to blow out the plugs for the head vents. So i did some testing and at lower rpm <3k-ish the engine would suck in air through the head vents but above >3k-ish it would switch to blowing out air (and oil) from the same vents. (IMG:style_emoticons/default/idea.gif) thats very useful empirical information. nothing like facts. i'm still laughing at the tin foil hat on the oil filler! sorry VaccaRabite - i do feel for you. thats two things that have disappeared into the void. make sure its not three. its the third one you got to watch out for. |
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