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OLD VW NUT Samba Member
Joined: February 23, 2011 Posts: 2776 Location: High Desert of Washington 98823
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Posted: Mon Aug 12, 2013 4:50 pm Post subject: Why you should not vent the L/H valve cover on 1600 motors |
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I read thread after thread about guys having problems with oil control on their motors - especially the 1835 and larger motors. The usual suggestion is to add extra vents on the valve covers. I'm going to show you why that may not be a good idea -thanks to Muffler Mike's efforts in researching his own oil leak problems - and how he found the cure for that leak.
Check out these photos from Muffler Mike's website:
http://www.mufflermike.com/news2000.html
This is a shot of the right side valve cover at 5000 rpms - very little oil pooling up in the valve cover
http://www.mufflermike.com/791.jpg
This is a shot of the left hand side at 2500 rpms -its beginning to fill up with oil - 3000 rpms is cruising speed on the freeway for most bugs/ghias. And you thought your oil was in the sump and doing it's job!
http://www.mufflermike.com/751.jpg
This shot is with rpms 'coming up' to 5000 rpms:
http://www.mufflermike.com/752.jpg
And at 5000 rpms the left hand valve cover is FULL of oil!
http://www.mufflermike.com/753.jpg
A 1600 based motor with no add-on sump holds about 2.6 quarts of oil. How much oil do you think that valve cover holds at 3000 rpms? I'm guessing more than 1/2 a quart. If you have aftermarket valve covers like I do that valve cover holds even more. And if your engine sees 5k rpms on a regular basis and you see the oil light come on - your motor is starving for oil. Don't vent the left side valve cover - instead do like I did with my motor and run a dump hose from the left hand valve cover to the add-on sump. Its a PITA when I need to adjust valves but its worth the effort IMO.
Now you know where your oil is during a cruise on the freeway - and why that left hand valve cover seems to perpetually leak. Any motor that sees 5k or more rpms on a regular basis should have a drain installed to return oil to the sump - and IMO an add-on sump is mandatory with the large high rpm motors. Even a stock 40hp motor will do this. _________________ 71 Ghia Coupe - stock body - no rust! Powered by a 2110 W/Dual HPMX 44's - Rancho Pro Street Transaxle - A/C by Gilmore
Other car - 2013 VW Golf TDI |
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spencerfvee Samba Member
Joined: August 19, 2004 Posts: 3071
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Posted: Mon Aug 12, 2013 5:29 pm Post subject: Re: Why you should not vent the L/H valve cover on 1600 moto |
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I all ways thought that there was a lot of oil in the valve covers at high RPM every time I see a big motor in a pipe buggy or bug with no deep sump . I just shake my head. and the next time I see them. there motor has wiped out the fly wheel main bearing . and they don't understand why . the buggy guys will say theres no room for a deep sump . or no one runs a deep sump so why should I . next time they blow a motor up I am going to show them the pictures mike posted on his forum thanks vw nut for posting spencerfvee
OLD VW NUT wrote: |
I read thread after thread about guys having problems with oil control on their motors - especially the 1835 and larger motors. The usual suggestion is to add extra vents on the valve covers. I'm going to show you why that may not be a good idea -thanks to Muffler Mike's efforts in researching his own oil leak problems - and how he found the cure for that leak.
Check out these photos from Muffler Mike's website:
http://www.mufflermike.com/news2000.html
This is a shot of the right side valve cover at 5000 rpms - very little oil pooling up in the valve cover
http://www.mufflermike.com/791.jpg
This is a shot of the left hand side at 2500 rpms -its beginning to fill up with oil - 3000 rpms is cruising speed on the freeway for most bugs/ghias. And you thought your oil was in the sump and doing it's job!
http://www.mufflermike.com/751.jpg
This shot is with rpms 'coming up' to 5000 rpms:
http://www.mufflermike.com/752.jpg
And at 5000 rpms the left hand valve cover is FULL of oil!
http://www.mufflermike.com/753.jpg
A 1600 based motor with no add-on sump holds about 2.6 quarts of oil. How much oil do you think that valve cover holds at 3000 rpms? I'm guessing more than 1/2 a quart. If you have aftermarket valve covers like I do that valve cover holds even more. And if your engine sees 5k rpms on a regular basis and you see the oil light come on - your motor is starving for oil. Don't vent the left side valve cover - instead do like I did with my motor and run a dump hose from the left hand valve cover to the add-on sump. Its a PITA when I need to adjust valves but its worth the effort IMO.
Now you know where your oil is during a cruise on the freeway - and why that left hand valve cover seems to perpetually leak. Any motor that sees 5k or more rpms on a regular basis should have a drain installed to return oil to the sump - and IMO an add-on sump is mandatory with the large high rpm motors. Even a stock 40hp motor will do this. |
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bugguy1967 Samba Member
Joined: January 16, 2008 Posts: 4343 Location: Los Angeles, CA 90016
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Posted: Mon Aug 12, 2013 6:21 pm Post subject: |
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I no longer vent valve covers on my builds. If vents at the case cannot suffice, then there must be a bigger underlying issue. On mild builds, I vent with the fuel pump mounting location and the stock stand. On bigger engines, I add another behind the shroud. Some say it weakens the case, but I haven't had any issues yet. _________________ "A petrol engine can start readily, run smoothly and give every appearance of being in good order, without necessarily being in good tune." - Colin Campbell, "The Sportscar Engine" |
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scotth17 Samba Member
Joined: January 30, 2012 Posts: 335 Location: Bedford Texas
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Posted: Mon Aug 12, 2013 6:30 pm Post subject: |
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Let's assume that the 3-4 side head is 3/4 full of oil at some given point. Wouldn't a vent be sort of an air break? I run vents on both sides and the gen tower and have no oil spilling out or such. I think a more interesting test would be the same setup with a clear vent tube in that valve cover routed up to where people normally mount breathers. Maybe test windage pushrod tubes also? Seeing is believing... |
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vwracerdave Samba Member
Joined: November 11, 2004 Posts: 15309 Location: Deep in the 405
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Posted: Mon Aug 12, 2013 7:44 pm Post subject: |
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I believe the 3/4 valve cover absolutely needs a air vent so oil can return back to the case. Without a vent the oil has to gurgle back into the case. Turn a bottle of soda upside down and watch the air gurgling into the bottle while the soda is gurgling out. Now poke a hole in the top and watch the soda flow out. The vent tube needs to be on the top of the valve cover towards the front of the car. Upon rapid acceleration oil is forced to the rear of the valve cover. Most people add the vents to low on the valve cover and oil can flow out the vent and spit oil into the breather system. _________________ 2017 Street Comp Champion - Thunder Valley Raceway Park - Noble, OK
2010 Sportsman ET Champion - Mid-America Dragway - Arkansas City, KS
1997 Sportsman ET Champion - Thunder Valley Raceway Park - Noble ,OK |
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Juanito84 Samba Member
Joined: March 17, 2012 Posts: 2436 Location: Colorado Mountains
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Posted: Mon Aug 12, 2013 9:05 pm Post subject: |
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vwracerdave wrote: |
I believe the 3/4 valve cover absolutely needs a air vent so oil can return back to the case. Without a vent the oil has to gurgle back into the case. Turn a bottle of soda upside down and watch the air gurgling into the bottle while the soda is gurgling out. Now poke a hole in the top and watch the soda flow out. The vent tube needs to be on the top of the valve cover towards the front of the car. Upon rapid acceleration oil is forced to the rear of the valve cover. Most people add the vents to low on the valve cover and oil can flow out the vent and spit oil into the breather system. |
I've thought about throwing in a sand seal and hooking up some vents to the covers, especially the 3/4 side, that would serve as "in's" and the one on the alt tower as the "out". I'd have to design it so that the "in" vents have, not only a filter, but slightly more pressure than the "out", either a blower, like a tap off the fan shroud, or using vac on the "out" side like a PCV valve or stock VW air cleaner.
The idea would be that the air flowing back to the crankcase would take the oil with it.
I do wonder, however, what are all the factors that fill up the valve cover like that. Sure, oil might be slung in that direction but it seems that vacuum succion through the valve guides finishes the filling of the valve cover. At WOT it shouldn't do that if my theory is true. But for those who use our Bugs as daily drivers we aren't going to drive around at WOT constantly. _________________ If a water cooled engine cools its water with air, isn't it just an overcomplicated air cooled engine? |
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slalombuggy Samba Member
Joined: July 17, 2010 Posts: 9147 Location: Canada
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Posted: Mon Aug 12, 2013 9:21 pm Post subject: |
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When you vent the 3/4 valve cover all you are doing is giving more oil more room to go to. Once the cover is full it will start being pushed up the breather hose and if you don't have a big enough breather tank you will find out as oil will be everywhere. By not venting the cover eventually it will create enough pressure in the cover to keep more oil from being slung up the tubes, yes it will be slow to drain back, but this is where the return line to the sump comes in. My engine sustains over 5500rpm for more than a minute shifting at 7500rpm and I can check the valvetrain after a run with no more oil dripping on the ground from the 3/4 side than the 1/2 side. I don't vent my 3/4 cover at all. I do vent 1/2, the fuel pump blockoff and run a CB breather tower. A also port the holes in the case going into the pedestal area, above the main bearing webs and a couple of other spots.
brad |
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bugguy1967 Samba Member
Joined: January 16, 2008 Posts: 4343 Location: Los Angeles, CA 90016
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Posted: Mon Aug 12, 2013 9:43 pm Post subject: |
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I've seen race cars tap into the bottom of the head right before the valve cover and run a steel braided hose to the external sump. Seems like a good idea for any car, but may be overkill on stock. _________________ "A petrol engine can start readily, run smoothly and give every appearance of being in good order, without necessarily being in good tune." - Colin Campbell, "The Sportscar Engine" |
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ralf Samba Member
Joined: July 08, 2008 Posts: 1215 Location: r4
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Posted: Mon Aug 12, 2013 10:42 pm Post subject: |
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bugguy1967 - then maybe tapping the head for NPT and hose would be cheap enough for stock builds just a thought..
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a coke bottle has 1 hole to drain from.. = pulls itself a bit from pouring out
we got 4 pushrod tubes on the 3/4 side + 2 additional drain backs
even with 1 drain back to the sump thats 5 routes
like slalombuggy says.. this is enough
and vent 1/2 side..
afterall .. these pressure buildup + oil thrown are all coming from the center/case
aleviating pressure at 1/2 side would mean more strength on the 3/4 side to push/return the oil down _________________ Flow Through a Curved Conduit
porting my SP head for my brother's project
https://youtu.be/OS_mVjQuqgk |
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mark tucker Samba Member
Joined: April 08, 2009 Posts: 23937 Location: SHALIMAR ,FLORIDA
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Posted: Tue Aug 13, 2013 10:03 am Post subject: |
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I think there was another issue with that motor, like the oil pressure relief valve, the exhaust for that valve is where?? yes right at the #3 exhaust pushrod tube.and it was probably filling the vc from that.might of had a bad spring, stuck open valve, or just way too much oil pump.
the cam&lifters are between the crank&the sump, and the cam is spining the other way, so it should be filling the 1-2 side, but it's not.it's the relief port. |
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Dale M. Samba Member
Joined: April 12, 2006 Posts: 20380 Location: Just a tiny bit west of Yosemite Valley
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Posted: Tue Aug 13, 2013 3:07 pm Post subject: |
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Two things I did not see mentioned is also using extended (windage) pushrod tubes and "windage tray" in sump, windage trays seem have fallen out of favor and I do not know why, though I don't use one.....
I vent 3/4 side, use additional 3.5 quart sumps and never have a oil buildup leak or breather overflow problem and my engines see 7000 rpm quite often...
Dale _________________ “Fear The Government That Wants To Take Your Guns" - Thomas Jefferson.
"Kellison Sand Piper Roadster" For Street & Show.
"Joe Pody Sandrover" Buggy with 2180 for Autocross (Sold)
============================================================
All suggestions and advice are purely my own opinion. You are free to ignore them if you wish ... |
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jhoefer Samba Member
Joined: May 19, 2011 Posts: 987
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Posted: Tue Aug 13, 2013 4:39 pm Post subject: |
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Would things work better if we could vent the valve covers to the top of the case directly and separately so as not to be routed through a breather box? Then run a separate breather line just for the case, like right off the oil fill.
We want the covers vented for drainage but the 3/4 side can overfill and flood a breather box, right? If the vent line went into the top of the case instead, you'd have a vacuum break to let oil drain out of the pushrod tubes, both the pushrod tube openings and the vent opening would be at the same air pressure in the case, so pressure differentials wouldn't really be pushing the oil anywhere more than it already is (not counting windage), and if oil does overfill the valve cover, it gets pushed through the vent line directly back into the case where we want it anyway. And by keeping the actual case vent away from the valve cover vents, we don't risk oil being pushed out the breather because we didn't have a large enough drain line on the breather box to accommodate that excess oil.
Does this seem sensible? Am I missing anything? Are there any good spots to tap into the top of the case without compromising strength or risking breakage? Fuel pump hole is an option of course for those with electric pumps, but I think this idea would work best if each vent line was separate, not T'd together into one spot. |
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Eaallred Samba Member
Joined: May 18, 2003 Posts: 5756 Location: West Valley City, Utah
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Posted: Tue Aug 13, 2013 9:44 pm Post subject: |
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I stopped venting valve covers and only vent the case these days.
Once I did that, my breather box and valve cover issues went away completely.
Venting valve covers is a V8 thing. It's the "top" of their motor. There is no practical way to vent the block on a V8. On a VW we have access to the top of the engine case. Seems a good place to add a "crank case breather", right? _________________ Eric Allred
You have to remember something: Everybody pities the weak; Jealousy you have to earn. |
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manoa Samba Member
Joined: January 08, 2006 Posts: 198
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Posted: Tue Aug 13, 2013 11:07 pm Post subject: |
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mark tucker wrote: |
I think there was another issue with that motor, like the oil pressure relief valve, the exhaust for that valve is where?? yes right at the #3 exhaust pushrod tube.and it was probably filling the vc from that.might of had a bad spring, stuck open valve, or just way too much oil pump.
the cam&lifters are between the crank&the sump, and the cam is spining the other way, so it should be filling the 1-2 side, but it's not.it's the relief port. |
He's right...
Steve Arndt wrote: |
From the hot vws article...
At high RPM and pressure, bypassed oil is diverted from the rear relief valve into the #3 lifter bore. From there it is pumped to the 3/4 head.
Jack's system puts the bypassed oil back to the sump directly so it doesn't get stuck in the rocker cover. |
[email protected] wrote: |
with the stock bypass, the oil winds up in the 3/4 valve cover, emptying the sump, which causes the pump to suck air. The new one dumps the excess in the sump, so the oil level does not drop as much since it's not filling up 3/4 valvecover. The pump sucks oil (not air) and your bearings thank you for it.
SCAT has made a similar item for a long time.
http://www.aircooled.net/new-bin/viewproductdetail.php?keyword2=eco0026
You have to have a pretty healthy engine to need these items, and I mean like 10 second cars.
Some people stick with regular filter mounts, but run a couple hoses from the 3/4 head (bottom of rocker box) to the sump, to get the oil back to the sump faster then just relying on the pushrod tubes to do it.
John
Aircooled.Net Inc. |
read it all here: http://www.thesamba.com/vw/forum/viewtopic.php?t=144970 Jaycee Oil By Pass _________________ -----
(o\ ! /o)
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Juanito84 Samba Member
Joined: March 17, 2012 Posts: 2436 Location: Colorado Mountains
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Posted: Tue Aug 20, 2013 2:57 pm Post subject: |
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The Jaycee system would bypass the oil back to the pump before it goes through the oil cooler, right? Unless you had an external oil cooler and put the Jaycee system after it.
But back on the oil gushing out the pressure control valve and filling up the LH valve cover. Is there a way to direct that oil flow either torwards the crank case pickup tube or even better yet, plumb it to the pickup tube itself? Kind of like the Jaycee system but using the stock valve in the stock gallery. _________________ If a water cooled engine cools its water with air, isn't it just an overcomplicated air cooled engine? |
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modok Samba Member
Joined: October 30, 2009 Posts: 26790 Location: Colorado Springs
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Posted: Tue Aug 20, 2013 3:30 pm Post subject: |
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yeah, use one windage pushrod tube on #3 exhaust, this blocks right in front of hole the oil comes out, then port a groove from the hole down so it directs the oil downward.
The WBX oil system plumbs the relief into the pickup line like you describe. That is of some interest and also the grooved relief bore. Some of those did eat rod bearings for no good reason, but I do not know if the cause of that is any fault of the oil system or people putting motor honey in it to keep the light off at idle. |
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Juanito84 Samba Member
Joined: March 17, 2012 Posts: 2436 Location: Colorado Mountains
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Posted: Mon Aug 26, 2013 8:15 am Post subject: |
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modok wrote: |
yeah, use one windage pushrod tube on #3 exhaust, this blocks right in front of hole the oil comes out, then port a groove from the hole down so it directs the oil downward. |
That's a great idea! I'm going to do that on my next rebuild! I wonder where you can find single windage pushrod tubes? I'll be on the search for one. Or I'll buy a kit and have enough for 7 failed tubes. I had completely forgot about windage tubes! _________________ If a water cooled engine cools its water with air, isn't it just an overcomplicated air cooled engine? |
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modok Samba Member
Joined: October 30, 2009 Posts: 26790 Location: Colorado Springs
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Posted: Mon Aug 26, 2013 5:05 pm Post subject: |
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They don't cost very much, and besides, if you want to convert them to STD pushrod tubes just cut the extended part off. |
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Juanito84 Samba Member
Joined: March 17, 2012 Posts: 2436 Location: Colorado Mountains
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Posted: Tue Aug 27, 2013 9:00 pm Post subject: |
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Found one!
http://www.piersideparts.net/MB8530.html _________________ If a water cooled engine cools its water with air, isn't it just an overcomplicated air cooled engine? |
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AlteWagen Troll
Joined: February 23, 2007 Posts: 8503 Location: PNW
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