I have the 1915cc engine and my mechanic says that I have too much crankcase pressure for the standard breather system. There are several solutions advertised. What do you think works best?
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I have the 1915cc engine and my mechanic says that I have too much crankcase pressure for the standard breather system. There are several solutions advertised. What do you think works best?
Several things can be done. FIrst is to add fittings to your valve covers and run the hose to a breather system.
several solutions here - - see: http://cbperformance.com/cataloglist.asp?Search=breather
Another way is if you have an electric fuel pump. You can buy a fitting that goes over the mechanical fuel pump hole and will provide a location for another breather line. see:
http://cbperformance.com/catalog.asp?ProductID=578
The center hole is blocked off so all you have to do is drill it out then install a fitting
several solutions here - - see: http://cbperformance.com/cataloglist.asp?Search=breather
Another way is if you have an electric fuel pump. You can buy a fitting that goes over the mechanical fuel pump hole and will provide a location for another breather line. see:
http://cbperformance.com/catalog.asp?ProductID=578
The center hole is blocked off so all you have to do is drill it out then install a fitting
Funny, I was doing research on just this topic this morning. My 1915 likes to push oil out. I am hoping venting of the valve covers will take care of it. I really want to use something like the CSP breather/oil filler. I really dont want to pay $300 for it.
Biggest advantage of this type of breather... no need to disconnect any hoses when pulling the engine.
http://www.vwparts.net/CSP115451100D.html
Biggest advantage of this type of breather... no need to disconnect any hoses when pulling the engine.
http://www.vwparts.net/CSP115451100D.html
First I would be looking into WHY there is too much crankcase pressure. Too much could be a sign of bad/weak rings. If it is within reason then why not just put a closed PCV valve system on the motor rather than a breather and catch can? The closed PCV system was to only thing good about smog emissions by getting rid of "road-draft tubes" and directing the "blow-by" to be burned in the motor rather than going up in the air. If it is done correctly a closed PCV system will provide negative crankcase pressure. The valve is one way and if the motor coughs it will not cough back into the crankcase. You need to plumb the valve/s into both intakes under the carburetors so any air coming into the motor from the crankcase is burned in the engine. The added benefit is a dry motor that will likely not leak any oil unless it weeps by the parting line of the case.
Just a thought.
Just a thought.
Dave,
Regardless of how good or bad the internal components are, modified VW engines produce a lot of internal pressure. It's inherent with the engine design.
I've built many, many modified engines and no matter what you do, they produce internal pressure. I've even done leak down tests, compression tests and found everything in order and they still produce pressure.
Venting the engine really does help to keep the engine from sprouting oil leaks..
Another method of producing negative pressure is to install a nipple on the exhaust pipe and run a high temperature hose to a vent on the engine. As the exhaust is exiting the pipe, it creates a vacuum and extracts the pressure from the engine.
Attaching a hose to the intake works but it get's your carb's or carburetor very messy.
Regardless of how good or bad the internal components are, modified VW engines produce a lot of internal pressure. It's inherent with the engine design.
I've built many, many modified engines and no matter what you do, they produce internal pressure. I've even done leak down tests, compression tests and found everything in order and they still produce pressure.
Venting the engine really does help to keep the engine from sprouting oil leaks..
Another method of producing negative pressure is to install a nipple on the exhaust pipe and run a high temperature hose to a vent on the engine. As the exhaust is exiting the pipe, it creates a vacuum and extracts the pressure from the engine.
Attaching a hose to the intake works but it get's your carb's or carburetor very messy.
This has been a topic I have devoted a great deal of time and effort to- and there is no really good answer, short of dry sumping the engine, and using the scavenging pump to draw a vacuum on the crankcase.
The crankcase on a Type 1 is pretty small, and with the increase in displacement, there is a whole lot of gasses moving around inside. While it should be true that one piston is going out while another is going in- it's also true that there IS some blow-by even when the piston rings have seated really well. 5% leakdown is still 5%. Add some windage in there, and it's no wonder 2L engines have a tendency to puke oil.
My case has some porting done in the "window" area between the front and back half of the case to allow as much gas as possible to transfer between. Last fall I put Total-Seal rings in to keep blow-by to the absolute minimum. I've got a windage tray and windage push-rod tubes in the engine, and a deep sump- I run the oil level as low as possible to keep the oil in the sump. There are guys running #12 AN hoses between the bottom of the valve covers, and the sump to keep oil flowing back to the sump as fast as possible.
I've gone so far as to connect a GM diesel vacuum pump to my crankcase breather to keep the crankcase in a vacuum. It was too much, and sucked oil right out the breather. I currently have a 6 qt. breather tank with #8 AN fittings connected to both valve covers and the fuel pump block-off, and a 10 AN connected to the breather towers. I'd love to have a 10 AN fitting coming off the 1 and 3 side of the case, but I didn't get it welded in before the engine was together. I'm coming off the top of the tank with 2 8 AN fittings connected to Bernoulli tubes inside the air filters (both sides). I'm using an Accusump as a pre-oiler, and to make sure I don't starve the bearings as I am running a pretty marginal oil level- I've got an oil pressure gauge to keep track of how I'm doing.
V8 drag racers use the set-up Larry described (Bernoulli tube in the low pressure area of the header collector), but if there is any restriction in the exhaust (back pressure, etc.) this may not work.
If my set-up doesn't work, I'll end up dry sumping. A dry-sump is just better in every way.
The crankcase on a Type 1 is pretty small, and with the increase in displacement, there is a whole lot of gasses moving around inside. While it should be true that one piston is going out while another is going in- it's also true that there IS some blow-by even when the piston rings have seated really well. 5% leakdown is still 5%. Add some windage in there, and it's no wonder 2L engines have a tendency to puke oil.
My case has some porting done in the "window" area between the front and back half of the case to allow as much gas as possible to transfer between. Last fall I put Total-Seal rings in to keep blow-by to the absolute minimum. I've got a windage tray and windage push-rod tubes in the engine, and a deep sump- I run the oil level as low as possible to keep the oil in the sump. There are guys running #12 AN hoses between the bottom of the valve covers, and the sump to keep oil flowing back to the sump as fast as possible.
I've gone so far as to connect a GM diesel vacuum pump to my crankcase breather to keep the crankcase in a vacuum. It was too much, and sucked oil right out the breather. I currently have a 6 qt. breather tank with #8 AN fittings connected to both valve covers and the fuel pump block-off, and a 10 AN connected to the breather towers. I'd love to have a 10 AN fitting coming off the 1 and 3 side of the case, but I didn't get it welded in before the engine was together. I'm coming off the top of the tank with 2 8 AN fittings connected to Bernoulli tubes inside the air filters (both sides). I'm using an Accusump as a pre-oiler, and to make sure I don't starve the bearings as I am running a pretty marginal oil level- I've got an oil pressure gauge to keep track of how I'm doing.
V8 drag racers use the set-up Larry described (Bernoulli tube in the low pressure area of the header collector), but if there is any restriction in the exhaust (back pressure, etc.) this may not work.
If my set-up doesn't work, I'll end up dry sumping. A dry-sump is just better in every way.
Danny P. post your set up, it works well on higher HP motors
Larry said:
Dave,
Attaching a hose to the intake works but it get's your carb's or carburetor very messy.
Larry,
As I stated a "properly" plumbed PCV system needs to be plumbed under the carburetors directly into the intake manifold/s. By doing this the engine becomes self venting and the crankcase pressure should be reduced to negative pressure. Nothing to get messy. Engines in the USA have had PCV systems since 1965. You will have to experiment with the hose and orifice size to get proper venting. You also have to seal the oil system. While I agree that modified VW motors will "build" crankcase pressure but it should NOT be excessive enough to blow oil out seals. If it is then the design somewhere has a flaw.
If you think about it other than blow by from the rings just the action of the pistons moving and crank turning should NOT create very much pressure. As one piston moves out from the crank one moves towards the crank and should offset any air movement creating a static pressure. So where does the pressure come from if not by the rings? It should not be so great that a properly plumbed and sized PCV system could not handle it.
There is more than one method to solve the same problem. I have only been twisting wrenches for about 40 years so I don't have too much experience.......;-)
Stan my friend you could copy the 911 design. It uses a wet sump with an oil tank and 12 quarts of oil in the system. The tank is vented.
Dave,
Attaching a hose to the intake works but it get's your carb's or carburetor very messy.
Larry,
As I stated a "properly" plumbed PCV system needs to be plumbed under the carburetors directly into the intake manifold/s. By doing this the engine becomes self venting and the crankcase pressure should be reduced to negative pressure. Nothing to get messy. Engines in the USA have had PCV systems since 1965. You will have to experiment with the hose and orifice size to get proper venting. You also have to seal the oil system. While I agree that modified VW motors will "build" crankcase pressure but it should NOT be excessive enough to blow oil out seals. If it is then the design somewhere has a flaw.
If you think about it other than blow by from the rings just the action of the pistons moving and crank turning should NOT create very much pressure. As one piston moves out from the crank one moves towards the crank and should offset any air movement creating a static pressure. So where does the pressure come from if not by the rings? It should not be so great that a properly plumbed and sized PCV system could not handle it.
There is more than one method to solve the same problem. I have only been twisting wrenches for about 40 years so I don't have too much experience.......;-)
Stan my friend you could copy the 911 design. It uses a wet sump with an oil tank and 12 quarts of oil in the system. The tank is vented.
Dave, I've been happy to take Larry's advice for a long time now, and I might be able to follow his logic just from years of exposure to the way he thinks. I really like the way both of you explain things, but I'm having difficulty with following you on this one.
I get the idea from Larry that he likes to work in an environment that's relatively sanitary; I'm guessing he sweeps the shop once before lunch and again before knock-off at a minimum -- and his advice to folks is just as functional. Clean is efficient.
I'm that way, and I wouldn't change it for the world. I'm an OCD kind of guy with machines.
I like your description of how you'd vent the case, and I'm curious why (not questioning what you're saying as valid, just trying to wrap my head around it) a vented case would still produce pressures of greater than 20 pounds. I think it comes down to displacement.
I'm scratching my head; assuming the connecting rods and pistons are all the same, the pistons and rings making a good seal in the cylinders ... then they all provide a steady-state volume inside the case while they're moving. Each connecting rod varies from TDC by 90, 180 or 270 degrees at any point from the others, making the case stroke average 50 percent of the possible stroke at any given time.
I get that. Steady state volume. Volemic pressure is minimal without heat.
Pressure, caused by heat inside the case from friction and thermal transfer, then, would increase with displacement and inadequate dissipation. Do I have that right? If so, then the larger the bore, the more cooling is required to keep the engine pressures down. By making pistons bigger, the amount of heat transfer into the rest of the engine's metal causes the engine itself to pressurize the vapors within by cooking them in a confined space. More piston, more heat.
More fan, less heat. External coolers, less heat. Vent the case to the atmosphere, vapors and heat also escape.
If all that's correct, I kind of get what you're saying, but don't see it as the most efficient answer. Venting pressure should be only half of the equation. The other half would involve cooling the oil. Like you said, there's more than one way to skin a cat -- I may just need a little more explanation -- especially the 'no mess' part.
I'm interested in your ideas for a couple reasons. If I understand you correctly, you're saying that you would use lines into the carb risers to equalize pressure by adding overpressure to the intake manifold side, letting the pressure harmlessly add to the vacuum and then mixing any oil vapors into the fuel pre-combustion. What are the consequences, if any, in the long run?
I think what Larry's suggesting is that it's not a good idea to introduce oil vapors to the gasoline side of the pistons at all; that the benefit doesn't make sense to him, and it's not clean.
I've got my own engine vented in the valve cover-to-breather method, and my case pressure eased by 10 pounds. That's all I can get out of it. At the same time, I added a second remote cooler. The primary is a bus unit; the secondary is an electric fan type. I did both at the same time, so I don't have independent data on what each mod did for me individually.
Second question is how to collect the suspended vapors before that vent -- before the intake, I mean -- to prevent oil from reaching the combustion side? Would you use a collector with its outlet above its inlets and run the outlet to a splitter and then on to the manifolds?
If Larry is suggesting not making the fuel-delivery side susceptable to any oil contact at all, and if you essentially agree, how would you ensure that?
Again, assume I speak Larry's language. I kind of like the more sanitary approach he suggests, but I'd love to have a more elegant solution than what I've got.
My case pressure usually lives in the 20-30 pound range at temperature.
I get the idea from Larry that he likes to work in an environment that's relatively sanitary; I'm guessing he sweeps the shop once before lunch and again before knock-off at a minimum -- and his advice to folks is just as functional. Clean is efficient.
I'm that way, and I wouldn't change it for the world. I'm an OCD kind of guy with machines.
I like your description of how you'd vent the case, and I'm curious why (not questioning what you're saying as valid, just trying to wrap my head around it) a vented case would still produce pressures of greater than 20 pounds. I think it comes down to displacement.
I'm scratching my head; assuming the connecting rods and pistons are all the same, the pistons and rings making a good seal in the cylinders ... then they all provide a steady-state volume inside the case while they're moving. Each connecting rod varies from TDC by 90, 180 or 270 degrees at any point from the others, making the case stroke average 50 percent of the possible stroke at any given time.
I get that. Steady state volume. Volemic pressure is minimal without heat.
Pressure, caused by heat inside the case from friction and thermal transfer, then, would increase with displacement and inadequate dissipation. Do I have that right? If so, then the larger the bore, the more cooling is required to keep the engine pressures down. By making pistons bigger, the amount of heat transfer into the rest of the engine's metal causes the engine itself to pressurize the vapors within by cooking them in a confined space. More piston, more heat.
More fan, less heat. External coolers, less heat. Vent the case to the atmosphere, vapors and heat also escape.
If all that's correct, I kind of get what you're saying, but don't see it as the most efficient answer. Venting pressure should be only half of the equation. The other half would involve cooling the oil. Like you said, there's more than one way to skin a cat -- I may just need a little more explanation -- especially the 'no mess' part.
I'm interested in your ideas for a couple reasons. If I understand you correctly, you're saying that you would use lines into the carb risers to equalize pressure by adding overpressure to the intake manifold side, letting the pressure harmlessly add to the vacuum and then mixing any oil vapors into the fuel pre-combustion. What are the consequences, if any, in the long run?
I think what Larry's suggesting is that it's not a good idea to introduce oil vapors to the gasoline side of the pistons at all; that the benefit doesn't make sense to him, and it's not clean.
I've got my own engine vented in the valve cover-to-breather method, and my case pressure eased by 10 pounds. That's all I can get out of it. At the same time, I added a second remote cooler. The primary is a bus unit; the secondary is an electric fan type. I did both at the same time, so I don't have independent data on what each mod did for me individually.
Second question is how to collect the suspended vapors before that vent -- before the intake, I mean -- to prevent oil from reaching the combustion side? Would you use a collector with its outlet above its inlets and run the outlet to a splitter and then on to the manifolds?
If Larry is suggesting not making the fuel-delivery side susceptable to any oil contact at all, and if you essentially agree, how would you ensure that?
Again, assume I speak Larry's language. I kind of like the more sanitary approach he suggests, but I'd love to have a more elegant solution than what I've got.
My case pressure usually lives in the 20-30 pound range at temperature.
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Throwing a saved note on the subject:
http://www.vw-resource.com/air_cleaner.html#crankcase (reference spiral groove on crank; pulley side)
http://www.vw-resource.com/air_cleaner.html#crankcase (reference spiral groove on crank; pulley side)
Thanks, Scott. Great reading!
Thanks to all for the information. Yesterday I ordered a short bus box along with welded valve covers from Gene Berg. I will let you know how it works out
be sure to let us know, if it stops your oil leaks,due to excessive crankcase pressure. bill
As Larry suggested, I have been using an exhaust venturi hooked to my crankcase for two years now. The difference with mine is I have a custom breather hooked to the case and both valve covers also. This is all plumbed with 1/2" ID hose. There is also a drain back into the crankcase for the condensed vapors.
The exhaust fitting is available cheaply from Jeg's. It is called a Pan-e-vac and was 18 bucks or so. I have it hooked up to an rpm trigger and 12v air solenoid, set to open above 5000 rpm. The solenoid is commercially available from places like Grainger, designed for air dryers. My thinking here is that the original VW motor was never designed to rev above 5000. So at 5000 or less, I rely on my custom breather. Above that, the exhaust literally sucks the blow-by vapors right out. Works pretty well, engine just has road dirt on it, not a covering of oil mist as before this system.
I'll have to wait a few weeks for photos, car is at the paint shop.
The exhaust fitting is available cheaply from Jeg's. It is called a Pan-e-vac and was 18 bucks or so. I have it hooked up to an rpm trigger and 12v air solenoid, set to open above 5000 rpm. The solenoid is commercially available from places like Grainger, designed for air dryers. My thinking here is that the original VW motor was never designed to rev above 5000. So at 5000 or less, I rely on my custom breather. Above that, the exhaust literally sucks the blow-by vapors right out. Works pretty well, engine just has road dirt on it, not a covering of oil mist as before this system.
I'll have to wait a few weeks for photos, car is at the paint shop.
I had problems with oil blowing out of the front of the engine on 2 different Type I engines. I installed sand seals on both which contributed to higher crankcase pressures I am certain. After a series of breathers, both commercial and shop made, my solution was a shop made breather made of 2" steel tube, 20" long that I mounted under the cowl of my Spyder, at the highest point. I ran AN-10 hose to the top of each valve cover, as well as to the oil fill tube. (this tube allowed collected oil to be routed back into the crankcase.) I also ran a 4th AN-10 tube to the top of the passenger side carb to provide a filtered "vent". I am not of the opinion this really generates any vacuum at all in the breather system as the entire air filter lies below the hose....any vacuum would be very slight....but also any fumes generated will go down the carb for certain I think.
This worked out well for me, the engines were both healthy and near new, rings were well sealed and the like...but no more oil any place, engine has been DRY for 10,000 kms....
This worked out well for me, the engines were both healthy and near new, rings were well sealed and the like...but no more oil any place, engine has been DRY for 10,000 kms....
My home-made breather is VERY similar to Jim's, in fact I admit to shamelessly copying it! It works well(mine) but I did find it lacking at highest rpms. Mine is a little different from Jim's, and am glad his worked out well. Mine was plumbed similarly but needed a little more help above 5000-5500 rpm.
I have a photo collection of oil breather configs from a couple of car shows. Amazing the various solutions.
Here are two...
Here are two...
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I have crankcase pressure now and then ....Beano works for me ~
TC woulda been all over this; he must be on vacation.
So . filling in for the FP ,
https://www.speedsterowners.com/forum/readmsg.asp?t=15282
Theres a SEARCH button people !
I KNEW we'd hashed this out b4
So . filling in for the FP ,
https://www.speedsterowners.com/forum/readmsg.asp?t=15282
Theres a SEARCH button people !
I KNEW we'd hashed this out b4
Cory,
You guys have somewhat closed minds on this subject because the solutions you are using work. That is OK with me. My point is if you plumb and vent the crankcase at the correct place you will NOT have any oil enter the intake side of the motor. The Chevy V-8 and Ford 302 have been doing it since 1965. On the VW you have a perfect place to start from at the very top of the system next to the oil cap. If you plumb the breather hose directly into the intake manifold/s you WILL create a vacuum and negative crankcase pressure. As I said the trick is just what size orifice is needed to create enough air flow to create the vacuum but not enough to suck too much so it sucks oil. Maybe Jake could do some testing on his next dyno run to see what would work. It would/could be a much cleaner and simpler system to use.
BTW if you have 20 to 30 PSI of crankcase pressure IMHO that is way too much.......;-)
You guys have somewhat closed minds on this subject because the solutions you are using work. That is OK with me. My point is if you plumb and vent the crankcase at the correct place you will NOT have any oil enter the intake side of the motor. The Chevy V-8 and Ford 302 have been doing it since 1965. On the VW you have a perfect place to start from at the very top of the system next to the oil cap. If you plumb the breather hose directly into the intake manifold/s you WILL create a vacuum and negative crankcase pressure. As I said the trick is just what size orifice is needed to create enough air flow to create the vacuum but not enough to suck too much so it sucks oil. Maybe Jake could do some testing on his next dyno run to see what would work. It would/could be a much cleaner and simpler system to use.
BTW if you have 20 to 30 PSI of crankcase pressure IMHO that is way too much.......;-)
...more Beano!!
Right on, Dave.
As you probably read in the link to the old thread, I've been looking for a better answer for a pretty long time. Now that I'm back home for the forseeable future, I would like to do what I can to remedy things.
Between rereading the old thread, your advice and Larry's, with a setup kind of like Danny's got and a well-placed set of hoses, I might finally understand what I need to do.
Seriously, thanks!
As you probably read in the link to the old thread, I've been looking for a better answer for a pretty long time. Now that I'm back home for the forseeable future, I would like to do what I can to remedy things.
Between rereading the old thread, your advice and Larry's, with a setup kind of like Danny's got and a well-placed set of hoses, I might finally understand what I need to do.
Seriously, thanks!
Attached is the installation. I did not add the breather because of oil leaks. After a year and a half, I did see an oil mist coating the engine and my mechanic noticed pressure coming from the oil filler hole. I am going to Morro Bay and wanted the assurance that the pressure would not cause a problem on the long trip. Thanks again for all the discussion. Even if it was discussed before, there are always new ideas.
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The breather system in my car is the one offered by Gene Berg and it has worked very well in keeping the engine compartment clean of oil but, plumbing it so that the right carb sucks in the vapors makes it very messy as Larry said. Right now I'm experiencing a hissing sound from my right Dellorto 40 along with a little erratic idling and darker smoke than usual at idle. As soon as you take off and shift to second and up the car works perfectly. This problem has been haunting me for some time and I wonder if it's due to a messy right carb.
Since the goal is to COOL/CONDENSE/SEPARATE the oil/gas vapor blowby , a block-mounted breather whose temperature is the same as the engine block is just the first (IMO unnecessary) step.
Thats why a remote tank is mounted OFF the engine.
Think a "STILL" for those of you bootlegger types. Gas vapor is the "distillate"
Thats why a remote tank is mounted OFF the engine.
Think a "STILL" for those of you bootlegger types. Gas vapor is the "distillate"