Oil leak form crank pulley

Riftvalleyvw · Post by **Riftvalleyvw** » Sat Dec 01, 2007 9:29 pm

I know. Sounds strange. But I have the report from VWoA. I will post it when I get back to Ethiopia. Most engine builders in the USA have seen this same report. Just ask them.

But, just think about it. if they were just trying to take care of the oil leak problem. Why go to such a complicated methode of stopping the oil from leaking? Could have just put in a standard seal and been done with it.. Just one part instead of the oil slinger and specal coring in the crank case and all the required machining on the pulley and case. The seal there would have even been really easy to change.....

forcecooled · Post by **forcecooled** » Sat Dec 01, 2007 9:58 pm

Now the crank touches the oil in the sump.
Now the dry sump pump creates negative vacumn in the case
Now the main seal operates under the full pressure
of the spillover oil from the bearing

KAK!

Post by **Tony Z** » Sun Dec 02, 2007 5:49 pm

Rift

While I do agree with you on what you are saying (mostly) I dont think you have it 100% correct when it comes to the scroll on the pulley and its function.

If you look at the scroll especially its depth and then check on the amount of clearance you have between the scroll and the case, it would make for a very very poor air pump. Any air that enters the scroll will just be slung out under centrifugal force against the case, causing only turbulance and not actually doing any pumping...
What is the use of this???

Ever heard of a labyrinth gland? Its a sealing arrangement used on turbo chargers, steam and gas turbines and other high speed machinery that doesnt need to stop a high pressure flowing, but rather stop a low pressure gas from passing it. The labyrinth gland does this by making a highly difficult route for any gas to flow through.... just like the scroll on the vw crank pulley.

While yes, you will prob find that a little air does enter the case, the scroll is primarily a seal and not a pump.

Post by **Tony Z** » Sun Dec 02, 2007 5:53 pm

forcecooled wrote:Now the crank touches the oil in the sump.
Now the dry sump pump creates negative vacumn in the case
Now the main seal operates under the full pressure
of the spillover oil from the bearing

KAK!

No the crank doesnt bathe in the oil.
A negative vacuum is actually pressure. You either have pressure or a (partial) vacuum. The scavenge pump in the dry sump pump is used to suck oil from the crank case... this is bigger than the pump used to pump the oil into the case to ensure that oil doesnt build up in the case. This does assist in removing gasses from the case and may produce a partial vacuum if the case is sealed and the blowby isnt much.

Post by **Tony Z** » Sun Dec 02, 2007 6:03 pm

Riftvalleyvw wrote: About the crank. The crank is not under the oil, but it is touching the oil. This is the reason why there are so many dry sump applications for American cars. It is probably more common that you think too. Most air compressors and refrigerant compressors use only splash oiling as it is called for lubrication. I have a 350 Chevy on a stand right now. When the rain stops I will take a photo and send it to you. If you are right I will send you something for your motor!

what is it and when do I get it????

Riftvalleyvw · Post by **Riftvalleyvw** » Sun Dec 02, 2007 7:26 pm

We will see tony!
Another note about the scroll on the crank pulley. It was introduced in 1961 along with the PCV system for California emissions. It did not exist before then.

Post by **Tony Z** » Sun Dec 02, 2007 7:33 pm

You've lost me.... PCV???

Riftvalleyvw · Post by **Riftvalleyvw** » Sun Dec 02, 2007 8:23 pm

Positive Crankcase Ventilation System. An early form of emission control. All cars have it, even today.
The Idea was to suck the blow by, oil mist and the gasoline that leaked out of the carbs while the motor sat out of the case, suck it back into the carb and reburn it. Trying to keep it out of the air.

forcecooled · Post by **forcecooled** » Mon Dec 03, 2007 1:10 am

Ehhhh-- My 1954 30 hp (36 hp in the US)
had an oil return thread on the pulley----

Riftvalleyvw · Post by **Riftvalleyvw** » Mon Dec 03, 2007 1:46 am

One groove.

Riftvalleyvw · Post by **Riftvalleyvw** » Mon Dec 03, 2007 2:13 am

I just did a quick search of the web and found these sites. ONe by a very respected VW guru.

http://www.vw-resource.com/crankcase_ventilation.html

http://bobhooversblog.blogspot.com/2007 ... ating.html

Bob hoover has a lot of interesting photos and diagrams for all you aspiring VW mechaincs. It is a very good read. You will need to look for the section on Crankcase ventilation.

Post by **calooker** » Mon Dec 03, 2007 7:20 am

I will start moving some of my stuff from storage to my home During the next week or so I will make a point of taking some pics of the cases I wave with the groove under the seal, I think one is a Mexican case the other a German.