Show full size 924Board.org
Discussion Forum of 924.org
 
 FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 
 Technical FAQ924 FAQ (Technical)   Technical924 Technical Section   Jump to 924.org924.org   Jump to PCA 924 Registry924 Registry

Oil in my air box

 
Post new topic   Reply to topic    924Board.org Forum Index -> 931 Tech.
View previous topic :: View next topic  
Author Message
poor-sche  



Joined: 06 Jan 2017
Posts: 13
Location: Los Angeles, CA

PostPosted: Sun Feb 25, 2018 1:40 pm    Post subject: Oil in my air box Reply with quote

My car has been running great, but it drips oil after driving. While trying to find the source of the oil leak(s) on my S1-931, I found this in my air box...



I took apart the Air/Oill separator, but the inside was actually not that bad. Just a lot of carbon buildup that easily cleaned up with a little scraping.

Further down the rabbit hole I went. I removed the intake manifold to get to the crankcase breather. Someone decided to attach the non-hex head hose clamp facing down so that the only way to remove it while the engine is still in is to cut it off with a




With the hose finally off...



Hereís what the inside of the breather looks like.



Does this look right? Is something missing? How should I go about cleaning it? Am I barking up the wrong tree? Should I have just checked compression?
_________________
1980 - 931
Back to top
View user's profile Send private message
Carrera RSR  



Joined: 08 Jan 2010
Posts: 1551
Location: Somerset, UK

PostPosted: Mon Feb 26, 2018 12:33 am    Post subject: Reply with quote

Turbos breath a lot of oil vapour. Condenses and collates in the air box and intake system. Worth checking out and cleaning. But will return.
_________________
1980 931 - forged pistons, Piper cam, CGT turbo, 951 ducted FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife LSD
Now www.924board.org/viewtopic.php?t=34690
Then www.924board.org/viewtopic.php?t=31252
Back to top
View user's profile Send private message
peterld  



Joined: 10 Dec 2006
Posts: 695
Location: Noosa Heads QLD Australia

PostPosted: Wed Feb 28, 2018 7:42 pm    Post subject: Reply with quote

These motors, even when in rude health, are heavy breathers. As the motor wears (piston/ring/cylinder walls) even more blowby is evident. The block vents to the air/oil separator where the droplets are hopefully caught, and the oily air passes onto the fuel distributor. Any oil caught in the separator drains back to the sump.
Your bottom picture of the block vent shows years of oily buildup. This could just be from years of running or could indicate heavy wear problems in the motor.
To get some idea of the condition of the motor, all things being equal, you need to clean out the vent, the separator and your airbox. Then further running will indicate the severity of the blowby (amongst other things)
Cleaning the vent is easy with the motor out, but almost impossible with the motor insitu. The vent is a hard press-in fit into the block, which is almost impossible to access with levers/etc while insitu.
On various motors I have worked on I have found the vent in numerous cases to be clogged solid (which yours almost appears to be). It has taken serious elbow grease to to dislodge the burnt/baked on tar.
This system was part of the emissions regime at the time. It is what it is.
_________________
80/81 932/8 ROW
Back to top
View user's profile Send private message Send e-mail
Eric P  



Joined: 21 Jun 2017
Posts: 167
Location: NY, USA

PostPosted: Thu Mar 01, 2018 12:19 am    Post subject: Reply with quote

Maybe someone can chime in on this. On my NA, there was a restrictor in the hose. It was basically a chunk of rubber with a 1/4" hole through it. It was molded inside the hose so it isn't shown on the PET. When I replaced my vent with radiator hose, I machined up a chunk of aluminum to fit in there and slow down the air flow through the vent.

Does the 931 have this? If so, it's possible somebody replaced your vent hose and didn't put a new restrictor in there? I'd bet that could cause a lot of oil in the intake if you have too much air flow through the breather hose.

*** This is just a guess. I don't know if the 931 and 924 have this in common as I don't have a 931.
_________________
1980 924 NA, US model
1987 924S, US model
Back to top
View user's profile Send private message
poor-sche  



Joined: 06 Jan 2017
Posts: 13
Location: Los Angeles, CA

PostPosted: Thu Mar 01, 2018 3:47 pm    Post subject: Reply with quote

Iím pretty sure I read the 931 didnít have the restrictor in the hose. My hoses look to be original and there definitely isnít one.



I would agree that removing the breather while the engine is in, without destroying it, would be damn near impossible. Iíve yet to see what the inside of a clean one looks like. Mine doesnít appear to be clogged in my opinion, but I donít know how clean it should be? I can stick my pinky into the tube and feel that there is a gap between the outer housing and inner ďbaffleĒ? Any ideas?



And for anyone interested in what the inside of the air/oil separator looks like, hereís mine with the cap off. The inside walls were covered in carbon buildup that came off easily with a little scraping. I plan on adding some steel wool and sealing it back up with silicone, so that I can reopen it easily if necessary. I read somewhere in an older thread that the wool acts like a baffle to help mitigate some of the oil in the air box. I suppose I should also make sure that the return line to the sump is clear as well.




_________________
1980 - 931
Back to top
View user's profile Send private message
Eric P  



Joined: 21 Jun 2017
Posts: 167
Location: NY, USA

PostPosted: Fri Mar 02, 2018 12:20 am    Post subject: Reply with quote

I personally wouldn't put steel wool anywhere near the internals of my engine. Steel wool tends to shed small bits of metal over time and it would work its way into your oil. If you really want to put something in there, I would lean towards one of those stainless steel pot scrubbers. They have much larger fibers and don't fall apart like steel wool will. I'd imagine you would have to put a lot of baffling material in there to make a difference. It looks like you would have to fill the cavity to the top.

Even if the 931 didn't come with a restrictor in the hose, I wonder if adding one would cause any issues? It works surprisingly well on the NA. Again, someone else will probably need to provide insight on that. Maybe a turbo builds crankcase pressure a lot faster than an NA and can't have a tiny vent?
_________________
1980 924 NA, US model
1987 924S, US model
Back to top
View user's profile Send private message
Carrera RSR  



Joined: 08 Jan 2010
Posts: 1551
Location: Somerset, UK

PostPosted: Fri Mar 02, 2018 12:36 am    Post subject: Reply with quote

Donít put anything steel in the Purolator. Obvious reasons

Donít restrict the crank case breather hose either on a turbo. You will cause other issues in the system. Intake system under vacuum pulls positive sump pressure out for a reason. If you donít want oil vapour going into the intake system, then use a vent to atmosphere oil catch can instead of the purolator. Recommended for higher boost engines. Not needed on stock boost. But you will end up with oil vapour build up in the engine bay which will need cleaning periodically.

Engines breath oil vapour. Turbo engines breath more oil vapour than NA
_________________
1980 931 - forged pistons, Piper cam, CGT turbo, 951 ducted FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife LSD
Now www.924board.org/viewtopic.php?t=34690
Then www.924board.org/viewtopic.php?t=31252
Back to top
View user's profile Send private message
ideola  



Joined: 01 Oct 2004
Posts: 15499
Location: Woodstock IL

PostPosted: Fri Mar 02, 2018 1:30 am    Post subject: Reply with quote

First, be aware that those breathers are NLA from Porsche, so you don't want to damage it in any way.

Secondly, you can try back-flushing thru the breather. Start with gasoline and see if you can get the worst of the sludge flushed down into the oil pan. Obviously, drain the existing oil first. Multiple flushes followed by some compressed air blasts should help. Be sure to VERY thoroughly flush the oil pan...lift the front of the car as high as you can get it to encourage all of the sludge to come out of the drain plug.

As noted above, 931s did not have a dowel in the breather hose, that was only for NAs.
_________________
15 981 GTS | 88 924S SE | 82 931 Holbert | 82 931 Rallye | 81 937 | 81 Euro 931 | 81 Weissach | 80 US 928 | 80 US 931 '941' | 80 US 931 | 80 931 GTR | 79 Sebring | 78 D-Prod Replica | 78 w/D-Prod kit | 78 Poli-Form | 78 Limited Edition | 77 Martini
Back to top
View user's profile Send private message
poor-sche  



Joined: 06 Jan 2017
Posts: 13
Location: Los Angeles, CA

PostPosted: Fri Mar 02, 2018 7:02 am    Post subject: Reply with quote

Eric P wrote:
I personally wouldn't put steel wool anywhere near the internals of my engine. Steel wool tends to shed small bits of metal over time and it would work its way into your oil. If you really want to put something in there, I would lean towards one of those stainless steel pot scrubbers. They have much larger fibers and don't fall apart like steel wool will. I'd imagine you would have to put a lot of baffling material in there to make a difference. It looks like you would have to fill the cavity to the top. Ö


Oops! Youíre right, stainless steel pot scrubber is what I was thinking.

Carrera RSR wrote:
Donít put anything steel in the Purolator. Obvious reasonsÖ


Do you think the stainless steel ball would come apart and make its way back into the sump?

ideola wrote:
First, be aware that those breathers are NLA from Porsche, so you don't want to damage it in any way.
Secondly, you can try back-flushing thru the breather. ...


Thanks for the suggestion.
_________________
1980 - 931
Back to top
View user's profile Send private message
Kenodog  



Joined: 25 Jun 2003
Posts: 2429
Location: Vancouver,B.C.

PostPosted: Thu Mar 08, 2018 6:06 am    Post subject: Reply with quote

One word for cleaning that shit out, Techron. Can't be beat.

Also, I thought Porsche was re-making those breathers ? I swear they were up on the 'Classics' website not too long ago...





Leigh
_________________
1979 Euro 931, Olive
1981 931, Sabine
2014 Mazda CX-5 (Kid's limo)
2008 GS500
1996 Dodge Caravan (DJV)
Back to top
View user's profile Send private message Send e-mail MSN Messenger
Display posts from previous:   
Post new topic   Reply to topic    924Board.org Forum Index -> 931 Tech. All times are GMT + 11 Hours
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2005 phpBB Group