Oil Filter

[vwglenn]

The consensus in the VW community seems to be that a filter on the suction side of the engine is a bad idea. It also hangs low and might take a hit if you straddle something on the highway (not a concern with an airplane).When I was at the Sonex facility for a tour @ Airventure this year I saw this...
http://www2.cip1.com/ProductDetails.asp ... D17%2D2872
..in their engine building room. Don't think I'd run it.

There is absolutely nothing wrong with running a filterless VW engine in my opinion. Just change the oil often and check/adjust the valves every time you change the oil.

The '67 Microbus I'm currently driving came with the engine as part of the project when I bought it. When I pulled the sump plate to drain the oil that was in it, it had 3/4" of sludge on top. I stuck my finger inside of the oil galley and pulled as much sludge out of the sump as I could. It had plenty of crusty bits in it but it was hard to tell if it was metal or what. Needless to say I didn't expect it to run. Still, I bolted on a carb, filled it with fresh oil, and it started after two turns. I ran it till it got nice and warm and changed the oil. Then I ran it 500 miles and changed it again. That engine remained in my bus for two years and ran faithfully every day (including a couple trips from GA to the Keys) until I pulled it out because it developed a leak on the pulley side of the engine. That leak had nothing to do with contaminated oil.

VWs are very robust little engines. They will take a BEATING and keep running. The key is to pay attention to them. If they have problems, they will let you know. They were designed a long time ago when tolerances were (intentionally) a little sloppy. The screen should catch anything that could bring it to a sudden stop. If the engine is making metal you have problems whether there's a filter on it or not.

[rizzz]

My case has been drilled & tapped for full flow filtering/cooling, I have the EMPI filter mount and the HP-1 filter.
I do also have the Gene Berg relief valve pump cover which should protect the filter and cooler when starting the engine with cold thick oil.

[vigilant104]

The builder of my plane installed an oil filter, it had a massive failure while on the ground (I don't recall if it was the seal or the filter seam itself). It has been running fine with no filter for over 200 hours.
The stock VW Type 1 didn't have a filter, and they ran for many hundreds of trouble-free hours with far lower quality oil, dirtier air, and much less pampering than we give out planes. I'd change the oil frequently during the break-in period, then faithfully every 25 hours after that (as recommended by Sonex). Easy, cheap, light, no filter/seal to fail and cause a power loss (or fire) in flight, it works, and it is what most people are doing.

[rizzz]

Just to stir the pot a little (most people know I'm a fan of a bit of debate on discussion forums ;) ), here's what VW legend Bob Hoover (not that Bob Hoover) had to say about the AeroVee oil filtering/cooling systems:

With regard to the method used by Aerovee, this type of pump cover was developed some years ago for the 'kiddie trade,' allowing youngsters to install an oil filter (and external cooler, if desired) without having to do any machine work on the crankcase. The method was never used on any professionally built engines that I know of for four pretty good reasons: The oil passages in the pump cover were small, restricting flow at full throttle, there was no provision for a pop-off valve, subjecting the filter canister and cooler core to pressures as high as 300 psi during a cold start, the inlet & outlet ports were separated by only a narrow land -- less than sixth thou as I recall -- the gasket of which had a habit of failing during a cold start, and -- perhaps worst of all -- the thing was made of cast
aluminum.

Most miss this last point because nowadays cast aluminum pump covers are enormously popular. Unfortunately, aluminum doesn't wear very well and the pump's steel gears will quickly grind a neat pair of circular craters in such covers. Since the end-clearance spec is only .002" as soon as that opens up you'd see a precipitous drop in both pressure and flow.

Given their years of experience and engineering expertise, I assume
Aerovee has solved all those problems. Along with how to keep the oil
clean without using a filter :-)

See the full discussion here, really good reading actually:
https://groups.yahoo.com/neo/groups/Air ... ages/12611

Now, for those of you who don't know about this Bob Hoover, he's probably the most knowledgeable VW expert the aviation community has ever seen, a lot of the common modifications that are currently done to turn a stock VW engine into a racing/aero engine were his inventions from back when he and his friends were racing these things in the 50's & 60's.
When VW later designed their type 4 cases they also incorporated a lot of Mr. Hoover's design as standard into those new cases (like his famous HVX mods).

That said, and this is me talking now, I find he treated VW engines built for aero applications the same as he treated VW's built for high rev racing applications, where the requirements are not always comparable, as might be the case on the oil filtering/cooling subject here.

Unfortunately Bob passed away a few years ago.
Luckily for us he was also a motivated writer and kept a very comprehensive blog detailing a lot of his VW (aero & street) related projects. Very, very very, interresting reading indeed:
http://bobhooversblog.blogspot.com.au/

[radfordc]

Now, for those of you who don't know about this Bob Hoover, he's probably the most knowledgeable VW expert the aviation community has ever seen,

At least he was in his own mind!

[thomasjones42]

This picks up on a very old thread but with some new information. I'm finishing up my Onex turbo and after two runs for a total run time of around 10 minutes the only oil leaks or seeps that I have are at the oil pump cover (very very light) and around the mini sump drain plug. I thought I would try replacing the sump drain plug crush ring and it seemed logical to also change the oil at the same time. After removing the oil sump drain plug I found a thin trickle of oil draining about the size of the lead in a yellow #2 pencil so I went to Sonex Builders net to research. In reading past threads this is not a new problem and seems to be generally attributed to the internal mini sump oil filter. The consensus was that the internal oil filter inside the sump blocks oil from draining rapidly. Assuming oil changes are frequent, there are posts that question whether this filter is/was even necessary. Additionally cleaning this filter entails removaI of the sump and the risk of creating new leaks when replacing it. These posts all preceded the addition of the external oil filter which is now part of the turbo installation. My question at this point is whether this internal filter is still necessary given that I now have an external oil filter. I would like to do frequent oil changes during break in but do not look forward to removing and replacing the sump each time. Any thoughts?

[n502pd]

Just my opinion, and that may not be worth much, since I do not have a turbo. But, I sure would loose the internal sump filter as the external filter, as is my setup, does a really good job by itself. I have never heard of a small engine like the v w having two filters. I now have aerovee with hp3 enternal filter and oversize lines to and from to the double size bottom oil cooler with aluminum cover plate for the pump. extra filter isnt needed!

[n502pd]

that would be a hp3 EXTERNAL filter..!!

[sonex1374]

I think the mini sump was an attempt to get a filter element into the engine in such a way that it had the biggest positive impact for the least amount of modification effort (best bang for the buck). In this regard, I think it's a good addition. However, if you're going to use an external oil filter, and you do that addition properly, there is really no benefit remaining for using the mini sump and filter. The sump itself may be desirable for the additional oil capacity, or form factor, or whatever, but I think the filter itself can easily be removed without causing problems. Personally, the less I have to mess with the oil sump, the better.

Jeff

[Rynoth]

I'm no engine expert, but in the Turbo setup the external oil filter is only filtering the pressurized oil that happens to be going through the turbocharger (which I don't think is very much flow at all,) wheras the mini-sump screen is filtering ALL oil that moves into the oil pump for circulation through the entire engine. Thus, I'd think it's entirely possible that without the oil screen any debris in the sump could circulate many times through the engine before ever chancing to make its way to the external filter (if it ever does at all.)