I have a question regarding the crankcase breather systems that people add as an upgrade, as trying to get my head around such things. This may come across as complete rubbish, but its still a question in my mind that I still don`t quite understand.
:-\
See if you can get your head around my thinking?
Originally, on my oil filler neck, I had one of those stupid little 2" air filters, and after a decent run my engine would be absolutely caked in oil. What hadn`t run down the side of this filter would have escaped through the pushrod tubes and landed on the floor - the engine leaked like a sieve.
:'(
However, after a top tip on here, I connected a pipe from the filler neck to the carb air filter, which as I understand was enough to give a little bit of negative pressure and has cured ALL of the oil leaks as a result, which is absolutely brilliant.
:)
However, I`m due to go twin carbs soon, so exploring options of how to retain the negative pressure here, if thats the right thing to call it.
Looking at a picture recently posted by Jazzy Early (knew you`d get the hang of pictures ;) ) of a fairly typical setup it got me thinking, as its a really clear picture of illustrating the breather system.
(http://i972.photobucket.com/albums/ae202/jazzyearly/Everythingconnected_zps3b4728e9.jpg)
Obviously the tube from the oil filler is a positive pressure and as a side effect, will throw oil up into the small ally reservior, where it will syphon back to the heads when the engine is switched off. But the two pipes that presumably come from the valve covers, are these also positive or negative pressure as well.
If positive pressure, and oil also escapes through here and up into the reservior, I can theoretically see the return of my old oil leaks from the pushrod tubes due to the extra pressure, and I have seen many of these ally reserviors with those small air filter type breathers on them, presumably to reduce any pressure.
However, an open filter to the elements is surely only going to "neutralise" any pressure, unlike the connection to the carb air filter that actually "applied" a little bit of negative presssure if you see what I mean.
So either I have misunderstood this whole concept, or am I right in thinking that an extra pipe needs to go from the ally reservior to the carb air filter to give an even more efficient system?
???
Dave
they are well worth fitting as the problem you describe isnt the only thing it fixes.
The box pictured (I have a brand new kit surplus to requirements) has a foam filter under the lid and is designed to catch oil and let it run back under gravity.
I dont know where is +ve or -ve on this setup and in fact I think it varies depending on how you are driving, in reality there should not be any pressure build up of any consequence.
Imagine you are gunning it round a big roundabout, you are pumping oil into the left hand rocker cover while gravity + the pumping pressure is all that you have to get it back down the pushrod tubes to the sump, so clearly centrifugal force is holding against the rocker cover and it aint running back, also the sump oil has moved left and is probably trying to force its way up the tubes, the rocker cover is probably getting a bit of +ve pressure at this point. If you have a breather box fitted it wont go up the pipe to the box because of the height of the box and the fact it is near the centreline.
So you come off the roundabout and straighten up with your left hand rocker cover full of oil, without a breather this can only get back to the sump if air can get past it into the rocker cover, so could be quite slow, fit a breather and air gets in via the pipe and oil goes back to the sump.
Only downside is that air can get out of the rocker cover while driving in circles allowing sump oil to run up the pushrod tubes easier, so (IMHO) a deep sump is a requirement, although I had oil starvation without a breather box on roundabouts anyway.
I reckon they are well worth fitting, will PM you my phone number if this raises more questions than answers give me a bell
Dave
Hi Dave, let's go back to basics. When vw designed the beetle engine, they built in a small ventilation system into it. This is because oil and water do not mix, you end up getting emulsified oil inside your engine. When you run an engine, with the change of temperatures; you get condensation and water vapours forming; so if you do not get rid of this water vapour it messes up your oil.
VW's idea was to build into there engines a small air pump, to suck air into the engine and then let it out from the breather buy the oil filler. If you look at an original oil filler, you will see that it has an oil catchment area; to let the oil return when the engine stops or is ticking over. The breather then either exited from a pipe running down and out at the bottom of the engine or on later engines it was connected to the air filter boxes. Which stopped them dripping oil everywhere ( the start of regulations). VW's little air pump is the spiral threaded bit on the bottom pulley.
So vw's idea works great until your engine starts to wear! Then every time your engine fires, more and more engine gases manage to get past the piston rings as they wear and it is these gases that pump through your engine, blowing oil and water vapours everywhere. If any fine filters are put on the breathers they will clog up with emulsified oil, which then pressurises the crankcases and makes them leak like yours did ;D
If you go for twin carbs, you can still connect a breather pipe to one of those. My personal opinion is that these fancy breather boxes are not needed on standard engines. Deep sumps are not needed either unless you are racing around or have bigger cc engines fitted.
So the bottom line is... when you get that other engine rebuilt and fitted, you shouldn't have so much oily air rushing out of your breather anyway ;-)up
Rob
This is a topic I have been interested in... OK so like Dave (DND) I had the little filter before too, and yes that side of the engines tin wear would get coated in oil from the breather filter.
Then Heritage insisted that I have some better form of breather kit on the engine (its reasonably spec'd 1776) - though I did query since the rocker covers they fit to the engine are rather nice Scat stainless steel ones, they have no option of porting for the breather pipes which is a bit crazy. Anyway, no problems I bought the breath kit (as pictured above) - I already have bolt on covers with porting from before anyway.
However just as I was about to fit it, Flags and Ollie (and others) suggested not to bother fitting it as it soon gets clogged up and you are forever cleaning it and in their opinion not that good overall. Instead, just port your oil filler breather to one of the carb filters (dual carbs).
Well, other have done the same and works well (including DaveDND) and to be honest, since I've done that too. Its spot on! ;-)up
I will hang onto my new untouched, breather box kit and bolt on covers for the time being just incase, there is a stronger case for them. (I do know others have them and they are fine) but so far the pipe to the carb filter is fine.
@Doon L001
I wasn`t aware that there was a foam filter at the top of those reserviors, but does clarify why the aftermarket made ally jobbies always have an extra filter on the top - I guess that they do the same thing. Yep, full understand what you have written, and no disagreements with the benfits of them as you describe.
@Farmer Rob
Brilliant description of the internal workings and design, but does kind of reinforce my thoughts.
Yes - I understand the "air pump" concept and the need to vent the water absorbed gasses to air.
Yes - I am in no doubt that my engine is FUBAR and is pumping more gasses than it should
But the question still remians though, rather than the air being pumped to the atmoshphere under its own pressure, does the addition of the pipe from the carb air filter, which will not only allow venting to the air as required, but also gives a little negative pressure meaning that the gasses can flow out of the engine even quicker ? Is this an extra benefit albeit miniscule ?
Hi Dave, I would say that the suck from the air filter is a good thing on a good engine but on an old engine, it could be blowing that much under load that pipe size could become an issue; so that the crankcase could still be slightly pressurised with the engine under load. The thing with an engine breather is that it has to let the engine breath but not build up pressure
If these breather boxes have a sponge filter in them, then I would remove it as it will only block and cause pressure issues.
Rob, surely if the blow from the engine is greater than the such from the carbs (which would be quite a feet) then the excess would be vented through the air filter on the carb.
Quote from: Roadrunner on August 21, 2013, 01:56:52 PM
Rob, surely if the blow from the engine is greater than the such from the carbs (which would be quite a feet) then the excess would be vented through the air filter on the carb.
Exactly, and by the same token, if the engine blow is of a very low pressure, surely a bit of suction from the carb would assist it?
I don't know who's engine this is but those valve covers really need swaping over so that the breather pipes run down the back of the engine. They're too easily pulled off or damaged where they are... ;-)up
(http://i972.photobucket.com/albums/ae202/jazzyearly/Everythingconnected_zps3b4728e9.jpg)
Quote from: Dave DND on August 21, 2013, 02:12:57 PM
Quote from: Roadrunner on August 21, 2013, 01:56:52 PM
Rob, surely if the blow from the engine is greater than the such from the carbs (which would be quite a feet) then the excess would be vented through the air filter on the carb.
Exactly, and by the same token, if the engine blow is of a very low pressure, surely a bit of suction from the carb would assist it?
As you said Dave, putting the pipe on yours to the carb has helped so evidence would say so.
And thats where the confusion kicks in . . . .
A lot of people upgrade to a crankcase style breather system as shown, which would suggest that over the years it has become a tried and tested method of doing things - (or simply that VW people are just sheep) - but I can`t help thinking that it could be very easily improved with another foot of pipe from the reservior box to the air filter
And if it really is that simple, why has no one else ever done it ?
Have seen these breather boxs mounted low ??? Would defeat the point ::) was told mount as high as possible ;-)up
And single breather if mounted high on bulk head could solve your problem ??? For a bit of pipe*** worth a try
( *** but can only condone the use of overly shiny stainless braided parts and fittings any thing else could result in time on the naughty step ) ;D ;D ;D
Quote from: Dave DND on August 21, 2013, 03:03:59 PM(or simply that VW people are just sheep)
Got it in one!
IMHO the only type of breather worth having is the Berg type one (or the similar CB Performance or Das Resto one) that mounts where the original VW oil filler mounts and drains any residue straight back into the sump. 95% plus of street engines don't need breathers to the valve covers anyway.
(http://dasrestoparts.com.au/media/catalog/product/cache/1/image/800x800/03d12213f51cf30066853880a6dd7cae/2/4/24295_3_1.jpg)
Thanks David - that picture is pretty much the concept I had running through my head
;-)up
when you look at how much air goes through the standard aircleaner intake there must be a depression in the air cleaner at high rpm simply putting your finger over the breather port with the motor running at speed will prove or disprove that fact.
pipes were returned to the cleaners for emissions control not because the manufacturers wanted to do it.
the problem is blow by in the motor pressurising the case due to the small size of the breather or restricting it with a fine filter.
the greater the volume/flow of the breather the less pressure is in the case to force oil out, higher rpm use, bigger CC's and engine wear apply more blow by volume thus pressure if it cannot escape
The jas has a box breather fitted high up just because it was there, but no sponge inside it
So relieving the pressure at the valve train by use of the generic crankcase breather systems as shown, should also (in theory) help to eliminate the oil leakage like my own current setup does then.
Not over worried about the other pro`s and con`s - just don`t want to reintroduce an oil leak now that it appears to have gone
Dave oil can seep through a joint slowly even when parked up and the pressure will have little effect on it but if you are blowing oil out of breathers, vents and seals in quantity the reducing the pressure could help.
start it up with your hand covering the oil filler hole to feel what pressure there is in the case, no oil should come out if the deflector plate under the stand is correctly fitted.
I don`t get any seepage when stood still, but before putting that pipe to the breather I would absolutely plaster the trailer in oil if I thrashed it down a motorway.
That little pipe has cured this 100% and now left me with a spotlessly clean trailer - engine is still knackered (no oil ;D ), but it was such a good and effective thing to do, that I want to make sure my next engine has all the help it can have from day one.
Like I said Dave, a worn out engine, working hard will push lot's of air out of the breathers with all those oil particles in it. As your new set up works well on your knackered engine, a similar system will work fine on a good engine. All that extra bling and expense isn't needed on a standard engine unless you want it of cause ;)
Rob
Thanks guys - that was some really good and detailed replies there ;-)up
The only thing I would add is that I managed to dump all the oil into one of my rocker covers until the yellow light came on, it then took ages to get back to the sump, almost 20 minutes later the oil was just starting to get back to the dipstick, once air started getting up the pushrod tubes as the level in there dropped it then flowed faster. Alright, I shouldnt have gone round the roundabout that fast, in that gear (2nd Andre not the lycra number), and until the oil had fully warmed.
A deep sump stops the oil pickup running dry and the breather lets air into the covers easily allowing the oil to drain back better, at least that is what I have found.
Mind you the quality of these kits, as with a lot of the bolt on goodies, is questionable. I have swapped all of the joints for top quality ones from Pirtek.
re the foam filter in those boxes, there is a metal mesh at the top of the box with a thin piece of coarse foam on top and a mm or so gap around the lid edge, after a year or two the foam was very oily but still permeable to air, so it needs cleaning but is unlikely to block completely so I wouldnt dump it. If another pipe was run from this to the air filter as someone suggested then the box would have to be airtight or it would simply suck air from the box, through the filter to the carb rather than suck from the crankcase.
One more thing to add, many aftermarket pulleys dont have the spiral but rely on a seal so there is no pressuring from that route, but just expansion and contraction of both liquid and metal, plus the turbulence in there, would still need a route to atmosphere to prevent pressure, +ve or -ve building up.
For me Rob is absolutely right, on a stock VW engine driven as VWs were meant to be, relatively sedately, they work perfectly well without any additional pipes or boxes. Start adding shiny bits, tweaking them and driving them hard round roundabouts and you just introduce problems, in my case a breather box helped solve one so I am a fan.
All the best
Dave
Some worthy additions there - especially the spiral on the aftermarket pulleys - thats one to watch out for indeed.
QuoteIf another pipe was run from this to the air filter as someone suggested then the box would have to be airtight or it would simply suck air from the box, through the filter to the carb rather than suck from the crankcase.
Ah . No . . . I was thinking of the addition of a slight amount of negative pressure to the box and not a Vaccuum, as that could bring a whole host of other issues
Dave, I reckon applying any intentional negative pressure to the box would just suck air into the box through the filter rather than up the pipes. Trying to reason out what is happening in the three pipes with the engine belting away plus all the centrifugal forces of cornering, acceleration and braking is making my brain hurt
Surely the passage of airflow would be less restricted from an open pipe entering the fiter box than through the substrate of the filter material ?
That way, as the carbs require more air, the pressure in the air box becomes heavily negative, this "assists" the flow from the oil pipe, but does not cause a heavy suction - and the remaining air requirements are drawn through the filter as normal.
The resultant effect is that instead of the air from the crankcase being "pumped" out to an ambient pressure, they are instead being gently "drawn" out, and the result is that a slight negative pressure here seems to prevent the oil from leaking out of every orifice when at full tilt.
This all could be absolute rubbish of course, but its just that connectng that little oil filler breather pipe to my air filter had such a dramatic effect, I`d like to understand why.
And yes, makes my head hurt too.
Please lock me out of this thread, enough :D
Quote from: Doon L001 on August 22, 2013, 01:47:15 PM
Please lock me out of this thread, enough :D
;D ;D ;D
Just remember, if you fit them, just make sure the connections to the rockers are good.........
Cos if not, and this happens..............
(http://i12.photobucket.com/albums/a214/gazapc/Baja/DSC09224_900x602.jpg)
And one ain't connected, added to a high mica content in ground.........
You'll end up with purdy shiney coloured engine oil....... ;-)up......if you're lucky.......
Needless to say.....GBH does not have them fitted anymore......but they sure did look pretty when they were! ;)
the way to stop oil loss into the rockers on cornering is
A) front tyres that do not grip thus relieving the G force on tight turns
B) push rod tubes with longer bottom sections so the oil stays in the crankcase.
C) drive sedately
Quote from: Doon L001 on August 22, 2013, 01:47:15 PM
Please lock me out of this thread, enough :D
Look its quite simple.... if you just follow this easy formula:
(http://static.guim.co.uk/sys-images/Admin/BkFill/Default_image_group/2012/3/2/1330704795252/maths-teacher-at-blackboa-007.jpg)
Its all just about sucking and blowing and stuff squirting out of places it shouldn't (Oil) ;-)up
Well, Im sorry Keith, but C) is not an option on this forum! I mean wash your mouth out!!!!!
:D :D :D :D
QuoteThanks guys - that was some really good and detailed replies there
Very! :)
Andrew you have a short memory the NEWS cruise was sedate, we were models of restraint and decorum through the villages and Ross on Wye ;-)(-;
Hmmm..... ;)
;-)up
Right.... The plot thickens...
As above I recently did the pipe from oil filler/breather to one of the carb filters. Note my spec given below. 500 mile trip this weekend, generally all good mostly on dual carriageways etc. cruising at 3000rpm may be a tad more. (A few rapid launches earlier in the day, but nothing too fast - revs within 5000rpm.)
Anyway last 100 miles or so noticed the engine wasn't as nice and relaxed as usual bit like a misfire may be, struggling low revs. Could it even be some dodgy fuel? i know others had similar issue and that would explan when it happened? (doubt it now though) . Clearly visible when checking it out tonight. So this evening disconnected the pipe and carb filter. Oil (not loads but certainly some poured out of pipe.
Then revving to 4000 and idling at 700-800, less smoke from exhaust, seems to run better. BUT. Get this... The exposed breather on the oil filler is puffing out quite a bit of air! Finger about inch away and you can clearly feel it constant. No oil coming out of course.
Now remember my case is autolinea, full flow but is different to the usual vw case. Remember heritage insisted on a breather kit. Anyhow, tomorrow ( when it's cooled) I will get the covers off, check valve gaps, compression, plugs etc. but looks like the simple pipe to carb filter is not the solution for me. Like I said, I know my engine is a tad different but once I know a bit more and having spoken to heritage tomorrow to see what has been done with other users of these blocks, will feed it back.
Engine n carb spec (not rolling roaded yet):
Autolinea Aluminium Race-Case with 10mm Chrome-Moly head studs
Engle 110 camshaft
Forged Counterweighted 69mm Crankshaft
Forged 4340 Chro-Moly 5.4'' I-Beam con-rods
Mahle 90.5mm Forged Pistons & Cylinders
Dual Thrust Cam Bearings
Steel backed Centre main bearing
SSP Big valve heads with 40 x 35.5mm stainless valves & 12mm Long-reach Spark Plugs
Uprated single valve springs & chrome moly valve spring retainers
Case drilled & tapped for full flow external oil filtration
Uprated Oil Pressure relief springs
Scat Bolt up rocker shafts & Swivel ball adjusters
Scat Heavy Duty Chrome moly pushrods
Scat Stainless Steel Rocker covers
Schadek 30mm oil pump
Cool tin under cylinders
Lightened & 8-dowelled 12V 200mm Forged Flywheel
Fully dynamically balanced
8.5:1 compression ratio
Pertronix Billet Dizzy with Ignitor 2 kit
with Flame Thrower 2 coil
Uprated HT leads
Serpertine pulley system
Dual EMPI HDMX twin choke 40s Carbs
put it down to still bedding in and if the carbs are not balanced 100% one side will work harder.
your first step is a compression test after checking the valve clearances to confirm all 4 cylinders are close, if they are get the carbs balanced.
Cheers Snoopy, yep kinda thinking the same. Ran out of time today, the run to the workshop wasn't brilliant, still missing a bit.
Checked valve clearances, close but needed a light tweak. It's certainly running rich (pipes quite sooty), compression test tomorrow - pretty sure that's fine of course but always good to have a point of reference for future too. Plugs out tomorrow to, pretty sure will be caked up a bit.
So sure it's not mechanical, so yes carbs need sorting likely and a few other tweaks may be. ;-)up
if the plugs are black they will soot up and misfire when running. so it needs the carbs tweeking have you tried just giving the mixture screws a slow wind in one at a time until it slows the rpm and winding them out 1/4 of a turn.
not an ideal way but it may help just so you can drive it.
it could be excesss fuel pressure or high float levels or the jetting is to big.
didn't you have this engine tuned recently? what did they tweek?
Yes am pretty sure you are right Keith, just not had a chance to day to look at it.
First needed to check it wasn't mechanical at all - which it isn't but you can imagine how paranoid I am with this engine. The tuning was just altering the timing and adjusting the idle screws on the carbs (didn't fiddle with mixture at all) A rolling road is truly called for and so will book that in soon.
I did think it may have been the oil (from the breather) heading into the right side bank. But yes certainly too rich noticed now both sides tail pipes are sooted up far more than before. so a quick tweak of the mixture, inspect/clean the plugs and we shall see. ;-)up
Of course taking this thread back on course, I wonder if I will go for the separate breathing on the rocker covers etc and not just the pipe into the carb filter.
Ok this is what I did;
This is my 6 way breather box. The top 2 vent into both carbs, these are separated from the bottom 4 by a perforated divide and a wire mesh type thing. Now based on my set up I have the middle 2 going to the rocker covers, middle for a reason. Because any residual oil or water vapour may dribble down if connected to the bottom 2. So, as above covers to the middle. The bottom 2, I only use 1. This comes from the oil filler and via a catch tank where by residual oil/water can drain back to from the breather box. The catch tank has a drain plug to periodically let the gunk out. Simples ;-)up
(http://i1230.photobucket.com/albums/ee483/David_Wainman/Image495.jpg) (http://s1230.photobucket.com/user/David_Wainman/media/Image495.jpg.html)
(http://i1230.photobucket.com/albums/ee483/David_Wainman/Image499.jpg) (http://s1230.photobucket.com/user/David_Wainman/media/Image499.jpg.html)
(http://i1230.photobucket.com/albums/ee483/David_Wainman/Image498.jpg) (http://s1230.photobucket.com/user/David_Wainman/media/Image498.jpg.html)
In this pick the redundant outlet is plugged with a pipe and bolt, just behind the main pipe in the picture
(http://i1230.photobucket.com/albums/ee483/David_Wainman/Image496.jpg) (http://s1230.photobucket.com/user/David_Wainman/media/Image496.jpg.html)
Hope this helps.
Great stuff, cheers Dave. ;-)up ;-)up
(As a minor aside, you realise your axle boots should ideally be in the 3pm / 9pm position and not noon? Though, that said, the bigger crime has to be they are yellow and not green!!! ;D ;D ;D ;-)up )
It shall be sorted when I put the chrome axle tubes, hubs, tube retainers and swing plates on ;-)up ;-)up ;-)up
Well....
Might be a total coincidence.....
But with the thread on breathers, and how it should go to the air filter and not one of the little filters that stick on the oil filler, I decided to do it last week.
So I drilled a nice hole in the bottom of my air filter plate, fitted a 90 degree elbow and run a nice pipe from there to where my little filter used to be.
Didn't drive it, didn't see the need.
Went to go to MBC last night, got less than 7 miles before I wondered what the white smoke was behind me..... Pulled over on the hard shoulder to find a bit of an oily mess.
In fact the only place there wasn't any oil was on the new filter pipe.
Seems to be mostly concentrated around the fuel pump pedestal area. Was hard to tell as it was all too hot to touch. So I limped it home and went to MBC in my normal car. (Can't keep me away)
This is how it looked this morning...
Again, it might be coincidence.......... But never had this happen in the 5 years I've been on the road. Only ever had the "standard" single drip from the push rods.
Got drops everywhere due to the vortex, under the air filter, on the body by the lights etc.
Even got a little pool of it in the little cut out in the side of the dizzy. So hard to see exactly where it's coming from until I can clean it up. (will be needing Krug to sort my exhaust )
Could it be that the new pipe isn't letting enough pressure out, so something had to give?? The pipe is about 1cm across. But the elbow joint is smaller.
Cause that can't be right, can't be that much pressure in there surely?
Maybe just a spooky coincidence?.......
Was fine last week when I drove it, touched nothing else but the filter, first drive I get the Exxon Valdez in the engine bay...
(http://i684.photobucket.com/albums/vv206/dan-peyto/IMG_3671_zpseed54988.jpg) (http://s684.photobucket.com/user/dan-peyto/media/IMG_3671_zpseed54988.jpg.html)
(http://i684.photobucket.com/albums/vv206/dan-peyto/IMG_3669_zps6713a2a3.jpg) (http://s684.photobucket.com/user/dan-peyto/media/IMG_3669_zps6713a2a3.jpg.html)
(http://i684.photobucket.com/albums/vv206/dan-peyto/IMG_3667_zps22ba0023.jpg)[/URL
(http://s684.photobucket.com/user/dan-peyto/media/IMG_3667_zps22ba0023.jpg.html)
now you have connected to your induction you are actually sucking engine fumes into your carbs .
I dont know why people do this in my opinion it shouldnt be done like this. my engine has the little filter on the oil fill tube and theres no gunge in at all. if its getting bunged up then the compression rings must be worn and causing crank case pressure.
keep it separate from the carbs.
but this is how VW did it themselves?
thats a std beetle engine , and air filter system.
yours isn,t
you said it was ok before you moded it thats why!
So. You don't think it's a coincidence?
Cause I don't have a mad monster engine, it a 1600, different cam, lightened flywheel etc and straight cut gears. But certainly not a beast
Dan it could well be excess pressure the brass adaptors tend to have thick walls and thus restricted flow compared to a steel pipe.
looking where its splashed up is it your bottom pulley spewing it out.
This is very interesting....
I too have a standard engine and have the same carb Dan uses, my oil filler housing also
has a take off thats routed to my air filter...
But I have never had this happen, one thing thats different between Dans engine and mine
is that I am using the original filler neck and cap, it is different in that it has a catchment area
between the pedestal and the breather pipe, whereas Dan's pedestal has the small bore
(in comparison) tube connected directly to it.
All I can say is that there must be a pressure difference that is encouraging the oil to find its way
past the bottom pulley boss, if that is indeed where its coming from...
It does sound as though this breather has caused it though, as Dan hasn't had trouble before.
I would be inclined to take it off again and then run without it for a while to see if it all stops....
Does any of that make sense...... ???
Peter
(http://i684.photobucket.com/albums/vv206/dan-peyto/IMG_3671_zpseed54988.jpg)
pressure will force oil out of the bottom pulley as it relies on a oil throw washer and a scroll on the pulley shaft to feed the oil back into the sump.
Fran probably blew his sand seal out at Le Mans with excess pressure as nothing can get past it due the a proper lip seal.
Hi Snoop ;-)up
Are saying that the use of these different ways to hook up to the oil filler can cause problems... ?
Does the standard VW set up change whats happening in there, as mine seems to 'catch' the oil and
allow it to find its way back with the breather tube (above) just venting oil mist and any pressure excess...
I was discussing this quite a bit with dan yesterday on the phone as I had what may/ may not have been an issue with that set up of breather. (To be honest I think it's more to do with carb air/fuel mixture - another story). But I was surprised how much oil was passing into the carb. Not so much as to be worried about, just surprising how much that's all.
Remember mine is a little more spec'd than dans, interestingly I have the same breather connection on the top of the filler - too narrow, could be the cause. But what was interesting for me was the amount of air coming out of the open breather when not connected. Certainly a constant puff whether on idle or revved. Never thought I had that much on the old type 3 1600. Compression test showed 130psi in each cylinder, mechanically still completely spot on (it only done 2k miles!!)
Dan was also shocked about the amount of air being pumped out of the breather, so may be as you guys suggest, narrow bore, length of pipe to filter is increasing crank pressure and forced oil out of bottom pulley. He said he was go run a few tests etc.
Quote from: Peter on September 07, 2013, 05:50:53 PM
Hi Snoop ;-)up
Are saying that the use of these different ways to hook up to the oil filler can cause problems... ?
Does the standard VW set up change whats happening in there, as mine seems to 'catch' the oil and
allow it to find its way back with the breather tube (above) just venting oil mist and any pressure excess...
Hp Peter,
Vw engineering should know piston blow by volumes be it by trial and error or maths then they know how big the breather has to be to allow the excess air volume out avoiding pressure build up and when folks modify engines these figures will change.
you can get complete seal rings like chord that reduce blow by on standard rings you have possibly a 15thou gap and air does escape into the sump every time it comes up and fires.
Well ....
Took the pipe off the air filter... The air that comes out is quite shocking.
Put it all back as it was and run it at 2-3000 revs on my drive .... no problem.
took it for a thrash round the block a few times ( its a big block ). No problem
Well apart from I had brake fluid squirting on my feet through the bulk head and my resovoir was almost empty .... Oops !
So bought a new one today. ( never just one thing with VWs is it )
So looks like, my engine doesn't like the pipe back into the carb at all.
Engine is tested at 93 bhp so it's a bit more powerful than standard.
Very odd !
straight cut gears up the pressure abit too,but im sure its the pipe you have is too small bore you need half inch at least,ive gone over board on mine rocker covers ,oil filler dynamo stand and where ive blanked of fuel pedistal as mine revs to 6500 it moves alot of air. :-)Geek
Thats good news Dan
It doesnt suprise me that there is a lot of air being moved what with 4 pistons
thrashing back and forth...
The restrictive and 'only' exit place is that fitting you had and its small bore...
The VW pedestal is a bigger area and it has an even bigger catchment box on the top,
the oil can separate and be trapped whilst any vapour or pressure can waft up the tube to the carb,
my 32/36 has no trace of much up there at all really....
So maybe thats it...
One thing ...... The elbow I used to join it to my air filter was the one that came with the carb.
The pipe is big enough to get my finger in. But the elbow is much, much smaller.
There was also no oil at all in the air filter. Not even a flick.
And ..... My air filter has really dense foam. Not sure it makes any difference though, just a point of bite.
That makes sense Dan......
'If' the oil was forced out past the bottom pulley, it was due to the restriction at the fitting on the oil filler cap.
You filter is 'upstream' of the restriction ans as such doesn't play a part in this!
At revs, the pressure that the four pistons create when they move toward the crankshaft is huge, the restriction
you fitted meant the oil was being forced out of the point of least resistance.
The bottom pulley uses whats called a 'Labyrinth' seal, its a 3 start thread, square sided and bottom, its helix
runs back towards the inside of the case when the engine is running.
There is a gap all round the bottom pulley boss and the case and the action of the multi start spiral (fast) causes air to be drawn in
and the thread form to catch and throw, any oil back inside the case.
ANY high pressure in the case due to restrictions at the filler area of the pedestal will cause oil to spew volumes out of this point.
Thats why the case breathing VW originally designed has large diameter bores, air can 'move' but not under high pressure.
Labyrinth seals are wonderful in that there is no contact or wear, so in a sense it lasts forever..... ;-)up
Does this make sense ?
Peter
Perfect sense Peter !
All cleaned up now and back as it has been for the last 4 years. ;-)
Now just need to change the brake master cylinder and finish the beetle ....
Oh did I mention my house is also on the market??.. So just a bit busy at the moment !!!
It now gives me the dilemma, do I...? :
A) Go back to just having the crappy little filter on my breather? Still can't believe its a good solution plus my tin wear on that side gets a bit grimy from the oil mist out of it.
B) Continue with the breather pipe to one of my Carb filters (But probably up the bore sizes where I can).
C) Fit the EMPI breather box (I had already got from advice from Heritage because on my engine) with the breather pipes from the filler and rocker covers - BUT make sure I regularly check the contents of it so its not all bunged up etc.
As a side issue, should we merge this topic with the other one of the breathers so all these thoughts, opinions, experience, findings etc. are together?
QuoteAs a side issue, should we merge this topic with the other one of the breathers so all these thoughts, opinions, experience, findings etc. are together?
That would be useful Andrew
I spect there are others that can comment better than I can, but what mustn't be overlooked is that the four pistons are HUGE pumps, working in reverse, they are moving a huge ammount of air as they travel down the cylinder bores.
Whatever is done to help the engine breathe, it really must be a large bore and have a catch tank, as the standard VW filler does.
Attached to this VW filler is a 16mm diameter down tube that lets any oil drain straight out...
To be honest I have never seen anything on an engine that does this job better, yet we throw it all away
???
MERGED!
I will also tidy it up and delete a few banter comments earlier on too - so it becomes a more useful debate thread. If thats all OK with you folks and of course delete this post too! I won't do all that until, the conscious agree. Might even be worth adding a sticky to it??