[Mgs] Mgs Digest, Vol 121, Issue 4

John Difede difejo at optonline.net
Fri Jun 9 16:47:56 MDT 2017


Excessive oil consumption.  
Joel,  use this test to see if you have excessive back pressure in the engine.   With the motor idling remove the oil cap. If oil or air pressure is coming out of the cap you have excessive back pressure.   If the carbs are sucking the crankcase fumes out of the motor you should have light suction at the oil filler hole.   Lay a tissue or a sheet of paper over the hole to check for suction.  Also if everything is working properly when you remove the oil cap the motor may want to stall.  This is be cause the open oil cap now allows more air into the crankcase and this can upset the air fuel mixture at the carbs as now more air is allowed to flow through the oil air separator into the y connector and into each carb. 
John Difede. 1973 with no emission controls pump etc. only the crankcase ventilation system installed

Sent from my iPhone

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> Today's Topics:
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>   1. Excessive Oil Consumption (Joel Martin)
>   2. Re: Excessive Oil Consumption (David Councill)
>   3. Re: Excessive Oil Consumption (PaulHunt73)
> 
> 
> ----------------------------------------------------------------------
> 
> Message: 1
> Date: Fri, 9 Jun 2017 13:06:01 +0000 (UTC)
> From: Joel Martin <jmartiniii at yahoo.com>
> To: "mgs at autox.team.net" <mgs at autox.team.net>
> Subject: [Mgs] Excessive Oil Consumption
> Message-ID: <717395960.5354080.1497013561376 at mail.yahoo.com>
> Content-Type: text/plain; charset="utf-8"
> 
> I rebuilt my 1973 engine last year.? Every thing all new except pistons .030 (AE) but installed new Hastings rings.? Valve job, cam etc.? I have had excessive oil consumption ever since.? Breakin oil used for first 500 miles with no more than 1/2 throttle during those first 500 miles and constantly up and down through RPM's up to 3500, back down then up again.? With over 250,000 miles on car and now 4th engine rebuild, this breakin procedure has worked fine, at least until now.
> 
> Assuming valve seals and piston rings are good ( I do not want to remove? engine to investigate at this point), lets approach from possible crankcase blow by.
> The emission pump and hardware has been removed since 1974 when the car came out of warranty, original owner.
> All new hoses, new oil cap etc.? The charcoal canister is still in place and was renewed about 4 years ago with new charcoal and filters.? Gas tank venting still in place and functioning with no gas smell in trunk and lines clear.
> I do not have gulp valve or PCV any longer and no oil separator on the crankcase breather tube.? The crankcase breather tube comes up with hose then y connector and splits into hoses running to the carburetor.? The gulp valve is the only thing removed this last rebuild and the PCV valve has been gone since 1974.? I have no run on after key turned off and no popping in exhaust.
> 
> The one thing I have noticed is the front carburetor has oil/grease residue on the dash pot (not oil from top of dash pot but oil residue) and even blowing back to the clutch and master cylinder.? 
> 
> Pulled the plugs the other day and they are perfect.? No compression test done.? With electronic ignition and carbs rebuilt professionally this time, (IE: not by me) due to throttle bodies leaking, the car runs and idles fine with easy starting.
> 
> All hoses are tight and clear of obstruction.
> I am currently thinking something to do with crankcase ventilation pulling oil past rings.??? By the way, I cut off the crankcase breather hose in front of the 'y' connector and have installed a white filter assembly on the breather hose to take most of the system out of play to see? what that does but only have about 60 miles on car since, so nothing concrete as yet and taped up the hose assembly going to the carburetor and zip tied the hose and connector out of way.? Need about 140 mile run to determine if this has any effect on test.
> Any and all thoughts about what to try would be greatly appreciated.
> Thanks in advance.
> Joel Martin
> 
> 
> 
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> Message: 2
> Date: Fri, 9 Jun 2017 07:46:35 -0700
> From: "David Councill" <dcouncill at karamursel.org>
> To: <mgs at autox.team.net>
> Subject: Re: [Mgs] Excessive Oil Consumption
> Message-ID: <005401d2e12f$31f359b0$95da0d10$@karamursel.org>
> Content-Type: text/plain; charset="utf-8"
> 
> What is ?excessive? in this case? If we knew roughly the miles per quart of oil, we would have a better perspective. 
> 
> 
> 
> David Councill
> 
> 64 B 
> 
> 67 BGT
> 
> 72 B
> 
> 
> 
> From: Mgs [mailto:mgs-bounces at autox.team.net] On Behalf Of Joel Martin via Mgs
> Sent: Friday, June 09, 2017 6:06 AM
> To: mgs at autox.team.net
> Subject: [Mgs] Excessive Oil Consumption
> 
> 
> 
> I rebuilt my 1973 engine last year.  Every thing all new except pistons .030 (AE) but installed new Hastings rings.  Valve job, cam etc.  I have had excessive oil consumption ever since.  Breakin oil used for first 500 miles with no more than 1/2 throttle during those first 500 miles and constantly up and down through RPM's up to 3500, back down then up again.  With over 250,000 miles on car and now 4th engine rebuild, this breakin procedure has worked fine, at least until now.
> 
> 
> 
> Assuming valve seals and piston rings are good ( I do not want to remove  engine to investigate at this point), lets approach from possible crankcase blow by.
> 
> 
> 
> The emission pump and hardware has been removed since 1974 when the car came out of warranty, original owner.
> 
> 
> 
> All new hoses, new oil cap etc.  The charcoal canister is still in place and was renewed about 4 years ago with new charcoal and filters.  Gas tank venting still in place and functioning with no gas smell in trunk and lines clear.
> 
> 
> 
> I do not have gulp valve or PCV any longer and no oil separator on the crankcase breather tube.  The crankcase breather tube comes up with hose then y connector and splits into hoses running to the carburetor.  The gulp valve is the only thing removed this last rebuild and the PCV valve has been gone since 1974.  I have no run on after key turned off and no popping in exhaust.
> 
> 
> 
> The one thing I have noticed is the front carburetor has oil/grease residue on the dash pot (not oil from top of dash pot but oil residue) and even blowing back to the clutch and master cylinder.  
> 
> 
> 
> Pulled the plugs the other day and they are perfect.  No compression test done.  With electronic ignition and carbs rebuilt professionally this time, (IE: not by me) due to throttle bodies leaking, the car runs and idles fine with easy starting.
> 
> 
> 
> All hoses are tight and clear of obstruction.
> 
> 
> 
> I am currently thinking something to do with crankcase ventilation pulling oil past rings.    By the way, I cut off the crankcase breather hose in front of the 'y' connector and have installed a white filter assembly on the breather hose to take most of the system out of play to see  what that does but only have about 60 miles on car since, so nothing concrete as yet and taped up the hose assembly going to the carburetor and zip tied the hose and connector out of way.  Need about 140 mile run to determine if this has any effect on test.
> 
> 
> 
> Any and all thoughts about what to try would be greatly appreciated.
> 
> 
> 
> Thanks in advance.
> 
> 
> 
> Joel Martin
> 
> 
> 
> 
>    
> 
> 
> 
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> Message: 3
> Date: Fri, 9 Jun 2017 15:49:19 +0100
> From: "PaulHunt73" <paulhunt73 at virginmedia.com>
> To: "Joel Martin" <jmartiniii at yahoo.com>,    <mgs at autox.team.net>
> Subject: Re: [Mgs] Excessive Oil Consumption
> Message-ID: <F114E6EE1601466E949A7638750CD462 at paul>
> Content-Type: text/plain; charset="utf-8"
> 
> You do need to do dry and wet compression tests.
> 
> If leaving it idling for a couple of minutes, then momentarily flooring the throttle, do you get blue smoke out of the back?  That indicates worn valve stems/guides, possibly rings/bores, the compression test should indicate which.
> 
> Is there any wet oil in the breather tube from the front tappet chest cover and the carbs?  Particularly at the Y connector and carbs?  If so that does indicate oil is passing that way.  You say you have no oil separator, do you mean you have removed the factory arrangement of mesh in the front cover?  That could well cause it.  There were also two types of cover with different holes and passages, and some have found the only way to cure oil consumption that way was to change the cover.  Also mounting a catch-tank above the cover port, with the inlet right at the bottom and the outlet at the top, should allow oil to be trapped but drain back into the sump at switch-off.
> 
> Do you have through-flow with the breather system?  There should be some suction on the hose from the rocker cover to the charcoal canister.  However with no through flow that should in fact stop any oil passing that way.
> 
> PaulH.
> 
> 
> 
>  ----- Original Message ----- 
>  ...
> 
> 
>  I am currently thinking something to do with crankcase ventilation pulling oil past rings.
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> End of Mgs Digest, Vol 121, Issue 4
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