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Re: Oil preasure / Vacume pump question
[Re: WH23H6]
#1228884
05/07/12 02:48 PM
05/07/12 02:48 PM
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Joined: Jul 2010
Posts: 2,091
Delray beach, Florida
Performance Only
top fuel
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top fuel
Joined: Jul 2010
Posts: 2,091
Delray beach, Florida
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i've never seen that happen with only 6" of vacuum. what size oil pan are you running?
i've seen hemi's that leak around the intake manifold internally that creat a lot of vacuum in the crankcase16-18" and still not have that problem.
are you using steel braided lines to the pump?
machine shop owner and engine builder
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Re: Oil preasure / Vacume pump question
[Re: Performance Only]
#1228887
05/07/12 04:30 PM
05/07/12 04:30 PM
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WH23H6
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Quote:
i've never seen that happen with only 6" of vacuum. what size oil pan are you running?
i've seen hemi's that leak around the intake manifold internally that creat a lot of vacuum in the crankcase16-18" and still not have that problem.
are you using steel braided lines to the pump?
Its a custom 10 Quart pan...been on the engine for 10 years...swinging pickup with duel lines...Milodon... # 12 braided to the pump...
No intake leaks...
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Re: Oil preasure / Vacume pump question
[Re: WH23H6]
#1228889
05/07/12 04:42 PM
05/07/12 04:42 PM
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Joined: Mar 2006
Posts: 9,910
Eighty Four, PA
B G Racing
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Quote:
She is sealed up pretty tight...
Sounds like its worth a try....project for tonight! [/quote
Give it a try,it worked on a few we have running out of BGR.68WV Charger(Pap and Allen Ross) had the same problem. 
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Re: Oil preasure / Vacume pump question
[Re: B G Racing]
#1228890
05/07/12 04:57 PM
05/07/12 04:57 PM
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Joined: Jan 2003
Posts: 5,875
communist bloc of new jersey
jamesc
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Quote:
If your engine is sealed up real good sometimes the vacume pump will pull the oil pressure away.
Bob not being argumentative but i'd like to know exactly what you mean by this?
imho the only way pulling a mild vacuum on the crankcase could possibly cause the problem you're having is by causing the pump to cavitate and/or cause air to be pulled into the suction side of the pump. make sure the suction side integrity is good and remember this side is under vacuum even without the vacuum pump so leaks are not always readily apparent. you should definitely be able to run 6" without issue. if you have a vacuum relief valve where is it located, what oil pump are you running?
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Re: Oil preasure / Vacume pump question
[Re: jamesc]
#1228893
05/07/12 11:00 PM
05/07/12 11:00 PM
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Posts: 134
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WH23H6
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Quote:
Quote:
If your engine is sealed up real good sometimes the vacume pump will pull the oil pressure away.
Bob not being argumentative but i'd like to know exactly what you mean by this?
imho the only way pulling a mild vacuum on the crankcase could possibly cause the problem you're having is by causing the pump to cavitate and/or cause air to be pulled into the suction side of the pump. make sure the suction side integrity is good and remember this side is under vacuum even without the vacuum pump so leaks are not always readily apparent. you should definitely be able to run 6" without issue. if you have a vacuum relief valve where is it located, what oil pump are you running?
This is what I was thinking...but I cant see where this is happening.... I pulled the pump tonight as well as the oil pan...no obvious problems... Its a Milodon pump, aluminum, duel external line pump. Custom oil pan..milodon swinging pickup..Vac pump relief valve is located on the top of the pump and is adjustable...separate gauge in the car...6" at 1200rpm
Un-screw the adjuster so there is no vabume pump vacume and it sits at 85lbs oil presure..at 1200rpm...no fluctuation....screw the adjuster in so there is 6" of vacume and the oil preasure goes away!
Seeing as how Im looking to get 14" at 7000rpm... its kinda freaked me out!!
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Re: Oil preasure / Vacume pump question
[Re: WH23H6]
#1228894
05/08/12 12:07 AM
05/08/12 12:07 AM
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Joined: Oct 2011
Posts: 3,036
bean town ....Ca
WHITEDART
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bean town ....Ca
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sounds like a small leak in between the oil pick up and the oil pump that the vaccume from the pump can get to ?
In the 8s N/A.with Brett miller W8's
5.07 at 133 at 2700lb
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Re: Oil preasure / Vacume pump question
[Re: dvw]
#1228898
05/08/12 08:09 AM
05/08/12 08:09 AM
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Joined: Apr 2004
Posts: 1,056
Mt.Vernon IL
Twin Turbo Mower
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Mt.Vernon IL
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What block are you using? I still think you are sucking the pan dry with the pump running and its not letting the oil drain back properly through the valley. My indy block did the same thing when I let too much oil go to the top end. I did not have restrictors in the oil lines to the heads. Once I put some in my oil pressure was fine. The indy block has small oil holes for drain back. With a vacuum pump running and air being drawn from the crank case through the valley it could restrict drain back. For now I would do what bg said and put a breather on the other valve cover.
Last edited by Twin Turbo Mower; 05/08/12 08:10 AM.
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Re: Oil preasure / Vacume pump question
[Re: Twin Turbo Mower]
#1228900
05/08/12 05:19 PM
05/08/12 05:19 PM
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WH23H6
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Quote:
What block are you using? I still think you are sucking the pan dry with the pump running and its not letting the oil drain back properly through the valley. My indy block did the same thing when I let too much oil go to the top end. I did not have restrictors in the oil lines to the heads. Once I put some in my oil pressure was fine. The indy block has small oil holes for drain back. With a vacuum pump running and air being drawn from the crank case through the valley it could restrict drain back. For now I would do what bg said and put a breather on the other valve cover.
Its the MP Mega block....stage 5 millenium heads....would putting a breather on the opposite valve cover just not defeat the purpose of the Vacume pump? I can't help but think is got to be a leak on the suction side of the oil pick up somewhere were in the vacume area... I took off the pan and pickup last night...couldnt see anything....the o-rings between the pickup and pan where nice and tight....All I know for sure is Im not nuts ! Its happening....
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Re: Oil preasure / Vacume pump question
[Re: dvw]
#1228901
05/08/12 05:21 PM
05/08/12 05:21 PM
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WH23H6
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Quote:
Is there actually no pressure or is the gauge wrong? It's been mentioned before that a vacuum pump acts on the gauge diaphragm.
Doug
I have a Mechanicle gauge as well as a 30lb trigger for my pro oil light...gauge hits 30 and the light is on....both devices are in separate sides of the block....
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Re: Oil preasure / Vacume pump question
[Re: B G Racing]
#1228902
05/08/12 05:26 PM
05/08/12 05:26 PM
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WH23H6
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Quote:
5" is correct,and this has happened and it has been corrected by the method I described.On Dave Ross' 540" wedge the pressure went to 0,he called the pump manufacture and they told him the same thing.He vented the engine and his oil pressure was rock solid and his pump was set for 5"
So did he restrict the vent just enough to still build Vacume? Do you know how much over all Vacume it made at high RPM? I was looking for about 13" at 7000.... I understand that any more than 13 or 14 will start to pull oil off bottom end parts...wrist pins and such...
The grief we go through just to try and put an "8" something on the window!!
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Re: Oil preasure / Vacume pump question
[Re: WH23H6]
#1228903
05/08/12 05:43 PM
05/08/12 05:43 PM
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Joined: Jan 2003
Posts: 5,875
communist bloc of new jersey
jamesc
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Quote:
Its the MP Mega block....stage 5 millenium heads....would putting a breather on the opposite valve cover just not defeat the purpose of the Vacume pump? I can't help but think is got to be a leak on the suction side of the oil pick up somewhere were in the vacume area... I took off the pan and pickup last night...couldnt see anything....the o-rings between the pickup and pan where nice and tight....All I know for sure is Im not nuts ! Its happening....
imho i agree putting a breather on the engine would not be the proper solution not to mention the greater chance of pulling oil out of the engine. vacuum pumps are supposed to pull gasses out of the engine not through it. i agree it would seem most likely there's a problem on the suction side of the oil system, or with the system in general. there are a lot of people running vacuum pumps without this issue. with regards to the pickup you would "expect" the entire pickup assembly to be submerged which should keep any leak there from causing a problem. although if there's a lot of oil in suspension the block portion might come uncovered.
this is one of those things that's frustrating for people trying to help because of not being there first hand.
i would think the possibilities are a vacuum leak on the suction side, oil staying suspended in the engine for some reason, or maybe really loose pump clearances...or maybe a combination of the above.
i know it's a stretch but any chance you have access to a couple -12 caps and could cap off one of the suction lines? if you were to do this it might identify a problem in one line or the other. one would think a visual inspection as you've done would expose any problems with the suction side. have all the O-rings on the pump and pickup fittings been inspected, i guess this would include the relief whatever you have in there.
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Re: Oil preasure / Vacume pump question
[Re: AndyF]
#1228909
05/09/12 12:17 AM
05/09/12 12:17 AM
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Joined: Jan 2003
Posts: 5,875
communist bloc of new jersey
jamesc
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communist bloc of new jersey
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Quote:
Yes, sucking the line closed would do the same thing. That is another good theory on what is going on.
i am by no means ruling this out because it is a potential problem though he said he already renewed the lines. not that doing that would correct the problem. i was under the impression that the vacuum rating of this type of hose was marginal but this is what Aeroquip says of their hose...
Quote:
The Performance Industry’s most popular racing hose.Stainless steel outer cover for excellent abrasion resistance. Excellent pressure rating (1,000 PSI from -04 to -12. AQP elastomer smooth bore inner tube. -45 to +300 F temperature rating, full vacuum (-10,-12,-16). Approved with reusable and crimp fittings. Applications include fuel, lube, coolant, air.
i read this as full vacuum in the -10, 12 and 16 sizes and we're no where near full vacuum.
i know it's really reaching but one thing i was thinking i might try if it was me (because it sounds like he's done most of the normal checks) would be to use a regulator and pressurize the engine. you would have to be VERY careful doing this and it may be an exorcise in futility but it might show a suction side leak if there is one.
one thing's for sure when he gets it resolved people need to know what it was.
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Re: Oil preasure / Vacume pump question
[Re: jamesc]
#1228910
05/09/12 12:39 AM
05/09/12 12:39 AM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
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Master
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Romeo MI
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Myself I would pull the swinging pick up out and install a braided line where the pick up mounts to the pan and just lay the end of the line on the bottom of the pan... just to eliminate the pick up... seen too many of them have O-ring problems and didnt like to prime 
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Re: Oil preasure / Vacume pump question
[Re: jamesc]
#1228911
05/09/12 12:46 AM
05/09/12 12:46 AM
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Joined: Dec 2004
Posts: 134
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WH23H6
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Quote:
Quote:
Yes, sucking the line closed would do the same thing. That is another good theory on what is going on.
i am by no means ruling this out because it is a potential problem though he said he already renewed the lines. not that doing that would correct the problem. i was under the impression that the vacuum rating of this type of hose was marginal but this is what Aeroquip says of their hose...
Quote:
The Performance Industry’s most popular racing hose.Stainless steel outer cover for excellent abrasion resistance. Excellent pressure rating (1,000 PSI from -04 to -12. AQP elastomer smooth bore inner tube. -45 to +300 F temperature rating, full vacuum (-10,-12,-16). Approved with reusable and crimp fittings. Applications include fuel, lube, coolant, air.
i read this as full vacuum in the -10, 12 and 16 sizes and we're no where near full vacuum.
i know it's really reaching but one thing i was thinking i might try if it was me (because it sounds like he's done most of the normal checks) would be to use a regulator and pressurize the engine. you would have to be VERY careful doing this and it may be an exorcise in futility but it might show a suction side leak if there is one.
one thing's for sure when he gets it resolved people need to know what it was.
Ok guys.... first of all thank you very much for all of your input...its nice to have a forum like this to discuss these types of issues that can cause us grief....this forum is perhaps the best tool we all have in our shops....let me tell you what I found...after removing the oil pan and checking all of the "hard" things.. I decided to do volume check on my custom 10 quart oil pan...it seems that at 10 quarts the level in the pan was just above the 2 out let holes for the Milodon pickup....after looking at it and assuming that even at idle...(1200rpm) at least 2 to 3 quarts of oil would be in motion in the engine...droping the level these 2 or 3 quarts would drop the level below the point where the swinging pickup attaches to the billit holding block...the swinging pickup is not O ringed...much to my suprise! I reassembled things and put 13 quarts in the pan...allowing for 1 quart in the remote filter and lines, 2 to 3 quarts in the engine while running.....problem solved! Vacume pump hooked up...idling at 1200...now have constant 85lbs preasure...
I bought the car last year and ran 10 quarts in it all year on the reccomondation of the previous owner...never had an issue...all of this only came to light after the winters changes...(Vacume pump)...thank god it happened in the shop at an idle and not on the back bumper at 7000rpm!!!
Seems the simplest things...as usual...are the ones that drive me nuts...
Thanks again guys (and gals!)...see you all on the track!!
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Re: Oil preasure / Vacume pump question
[Re: MR_P_BODY]
#1228913
05/09/12 01:01 AM
05/09/12 01:01 AM
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Quote:
So what is leaking at that point where it attaches
to the pan
I think it was where the swinging pickup attaches to the holder that bolts to the pan...there is no O ring...only a cottor pin that allows it to swing...when this got below the oil level it must have allowed the crankcase vacume to pull there and cause the pump its issues....keeping more oil in the pan and keeping this point covered seems to have corrected it...
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Re: Oil preasure / Vacume pump question
[Re: MR_P_BODY]
#1228915
05/09/12 01:13 AM
05/09/12 01:13 AM
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Posts: 134
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Quote:
tQuote:
Quote:
So what is leaking at that point where it attaches
to the pan
I think it was where the swinging pickup attaches to the holder that bolts to the pan...there is no O ring...only a cottor pin that allows it to swing...when this got below the oil level it must have allowed the crankcase vacume to pull there and cause the pump its issues....keeping more oil in the pan and keeping this point covered seems to have corrected it...
thats where the O-ring is suppose to be(I believe)...
you better look into that... cant run with just 3 qt
useable oil... with the bit of pressure you had in
the crank case it maintained a seal (before the vac
pump)
I dont think it ever had an O ring...the groove in the pickup is just big enoungh for the cottor pin to allow the swinging motion...putting an O ring in this groove would stop the swinging motion...kind of a piss poor design by Milodon if you ask me...but whatever....I think they should have double grooved it and had an O ring as well...
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Re: Oil preasure / Vacume pump question
[Re: WH23H6]
#1228916
05/09/12 01:35 AM
05/09/12 01:35 AM
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Joined: Jan 2005
Posts: 3,699
Newport, Mi
Evil Spirit
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Newport, Mi
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It makes sense that no o-ring where you describe would cause a problem. With the engine sealed up, applying a vacuum to the crank case area will do 2 basic things. (1) Vacuum in the oil pan area would make it harder to pull oil through the oil pump intake system, be it just a conventional pickup tube or a swinging pickup, resulting in a loss of pressure. Even properly sealed it would be harder to get oil into the pump - unsealed it would just suck air and not make pressure. (2) On the pressure side of the oil system, everywhere that oil is usually forced out under pressure (bearings, lifters, rocker arms, etc.) will also have vacuum trying to pull the oil out, also resulting in loss of oil pressure. Pretty much every vacuum system I've seen has shown some oil pressure loss on back to back belt on/off testing. 
Free advice and worth every penny...
Factory trained Slinky rewinder.........
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Re: Oil preasure / Vacume pump question
[Re: Evil Spirit]
#1228917
05/09/12 01:42 AM
05/09/12 01:42 AM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
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Romeo MI
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Quote:
It makes sense that no o-ring where you describe would cause a problem. With the engine sealed up, applying a vacuum to the crank case area will do 2 basic things. (1) Vacuum in the oil pan area would make it harder to pull oil through the oil pump intake system, be it just a conventional pickup tube or a swinging pickup, resulting in a loss of pressure. Even properly sealed it would be harder to get oil into the pump - unsealed it would just suck air and not make pressure. (2) On the pressure side of the oil system, everywhere that oil is usually forced out under pressure (bearings, lifters, rocker arms, etc.) will also have vacuum trying to pull the oil out, also resulting in loss of oil pressure.
Pretty much every vacuum system I've seen has shown some oil pressure loss on back to back belt on/off testing.
Your correct that it will be a bit lower in oil pressure...
2 inch of merc is 1 psi so with 11" of vac thats 4.5
psi lower... big deal... but with the vac on the rings
they seal better and end up making 20-45 more HP
Last edited by MR_P_BODY; 05/09/12 01:44 AM.
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Re: Oil preasure / Vacume pump question
[Re: MR_P_BODY]
#1228918
05/09/12 01:56 AM
05/09/12 01:56 AM
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Joined: Jan 2005
Posts: 3,699
Newport, Mi
Evil Spirit
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Quote:
Quote:
It makes sense that no o-ring where you describe would cause a problem. With the engine sealed up, applying a vacuum to the crank case area will do 2 basic things. (1) Vacuum in the oil pan area would make it harder to pull oil through the oil pump intake system, be it just a conventional pickup tube or a swinging pickup, resulting in a loss of pressure. Even properly sealed it would be harder to get oil into the pump - unsealed it would just suck air and not make pressure. (2) On the pressure side of the oil system, everywhere that oil is usually forced out under pressure (bearings, lifters, rocker arms, etc.) will also have vacuum trying to pull the oil out, also resulting in loss of oil pressure.
Pretty much every vacuum system I've seen has shown some oil pressure loss on back to back belt on/off testing.
Your correct that it will be a bit lower in oil pressure...
2 inch of merc is 1 psi so with 11" of vac thats 4.5
psi lower... big deal... but with the vac on the rings
they seal better and end up making 20-45 more HP
Yep - not knocking the need for the vacuum system, Raff - just trying to shed a little light on why the system can affect oil pressure.
Free advice and worth every penny...
Factory trained Slinky rewinder.........
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Re: Oil preasure / Vacume pump question
[Re: Evil Spirit]
#1228919
05/09/12 02:22 AM
05/09/12 02:22 AM
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Joined: Jan 2003
Posts: 5,875
communist bloc of new jersey
jamesc
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Quote:
I dont think it ever had an O ring
and afaik you would be correct. when i first dealt with these things i questioned that wisdom. a seal makes it drag, without it there's a potential leak. like i mentioned one concern i had was if any portion of the PU became unsubmerged and it sounds like it did.
great to hear the problem is solved
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Re: Oil preasure / Vacume pump question
[Re: dvw]
#1228921
05/10/12 06:56 PM
05/10/12 06:56 PM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
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Master
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Romeo MI
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The one swinging BB pick up I had years ago had a O ring in it(dont recall who the manufacture was) but it was a bit snug and I thought it didnt swing well but at least it didnt suck in air
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