So I permanantly blocked my oil filter bypass

[ME 109]

Without going back to read all the detail, is it plausible to just change the oil filter cavity? Would that solve the issue with the spring seat? I'm unsure of the anatomy back there.

Na Steve, the damage is to the engine case. The oil filter cavity is created by an open ended steel sleeve, much like a dunny paper roll, that presses into a circular slot in the engine case at one end, with the filter cover or thermostat at the other end.
The oil filter inlet, outlet and bypass valve are 'within' the confines of that steel tube, all the way down the far end, but are part of the engine case.

I still think I can make this work, using the thermostat. I'll have to wait about 4,000 k's until I'm in there again changing the filter. Then I can measure and know what's what.

[SteveD]

Ok. I knew the oil filter cavity pressed in, but I was thinking that the necessary bits were part of it, not the case.

What's the plan if what you've done doesn't work out?

[gspd]

The Mystic and GS with factory coolers use the same cover. Why the design was changed in 2016 (21 years after airhead production ceased) is unclear to me, but I think it has to do with what happened to me almost 3 decades ago. (read on)

Back in 1990, during my first long trip on my (then new) R100GSPD (prod 11-89), my oil cooler sprung a bad leak about 1000 miles from home. I had the bike towed to the closest BMW dealer. After a few calls to my bud Norm Wells, big shot at BMW Canada HQ, the dealer reluctantly agreed to give me a new cooler cannibalized from a showroom bike so I could continue on my journey. Shortly after, a service bulletin was issued instructing dealers to enlarge the small return hole (to 4mm) on all bikes so-equipped during regular servicing. Seems like mine was not the only one that blew up. This was to prevent excessive pressure in the cooler. No problems since. The small hole you see in this picture is the one that had to be enlarged.


All this brings me to the point of this post. How does BandWagonJumper's (filter mounted near the transmission) setup work??
My queries:
1- What internal modifications were done to assure that ALL his oil is being filtered, not just what would be normally going through the cooler?
2- What pressure relief system is being used? without one the filter will eventually distort and blow up. Maybe he's still using the one that you blocked on your bike, in which case his system will not solve your problem.
3- How and where could you add a cooler to this system? Oil coolers are not designed for high pressure.

[Wobbly]

I checked a parts supplier website and yes, the Mystic type cover is the one.

Yes, and that's what you want. Full-time oil flow to the filter.

The thermostat type cover only routes about 90% of the oil to the cooler becasue the internal shuttle really doesn't fit that tightly in the housing. That's OK with the cooler in place becasue you only need to cool a large percentage of the oil, not every single drop. However, with the oil filter you'll want to be assured every drop of oil is being cleaned.

These GS-type oil filter covers show up on Ebay all the time. Search on "BMW filter cover".

Need to look for a stand alone oil filter base, or cut one off something. That shouldn't be too difficult.

Bring up Amazon and do a search on "oil filter base". About 9 units will show up, 3 or 4 of which are the same base simply supplied with different fittings.

[Wobbly]

Not sure how big that filter is, and whether that size is equivalent to the filter area of the stock paper filter.
And then there's micron size? How fine do auto filters filter?

An older auto parts store that still has the paper books can answer your question. In the back of the older paper books is a cross-reference chart that gives the physical size, thread size, and micron rating of each filter. You might also look up the Purolator Airhead filter so you can have an accurate reference point to judge replacements.

As to filter size, a standard Ford Z9 is too big, but perhaps the Jeep size is more suitable.
Just had a look at the filter on my kohler mower engine. It's about 3" x 3" Perhaps it will suffice.

I've already suggested the filter from a '98 Toyota 4-cyl as having adequate flow. (If it's big enough for a 5-main bearing 4-cylinder, then surely it will work on an Airhead.) I recently read where 'Oak' Okleshen recommended changing the filter every other oil change because once the engine is run-in it simply doesn't generate a lot of particulate matter. The same thing applies in your case. Worrying about filter capacity is a moot point for your seasoned engine.

[gspd]

Wobbly said:

The thermostat type cover only routes about 90% of the oil to the cooler

The actual percentage of oil routed to the cooler is hard to determine precisely, but suffice it to say, it is definitely way less than 100%.
This applies all the airhead covers that have cooler passages, wether or not they have a thermostat. (refer to my last post)

[Wobbly]

I think most use standard NPT threads.

NPT is a tapered thread and wouldn't work for obvious reasons. 3/4-10 UNC was by far the most prolific thread when doing my oil filter search years ago. I believe all these "after market" filter bases are going to use that thread.

Also, what do you plan on doing about the cavity the stock oil filter was housed in? You can't just leave it empty.

Actually you can. But you will need the following...
1) The "white o-ring" in there to seal the housing to the cover
2) The longer oil filter center rod, which you may end having machined special for you. What you want is a rod that goes straight from the engine to the oil filter cover. In this way all the filtered oil gets delivered straight from the new filter location to the engine.

[gspd]

1- OOPS! I misspoke when I said standard NPT threads, I meant standard threads.

2- I'm pretty sure that a straight through pipe with no source of pressure relief would blow up the filter and cooler. Every engine that I know of has a pressure relief system of one kind or another before the filter. The PSI at the oil pressure switch is always much higher than the pressure in the filter or cooler.
I remember from my VW days of yore that when they redesigned type 2 engines and went from the old strainer system to renewable filters, they had a lot of filter blow-up issues before working out the appropriate pressure relief valve plumbing and calibrations.
I think maybe the fact that Jeff is having no immediate issues with his blocked by-pass may be because his paper filter element has blown up inside the housing and the excess pressure is just draining back into the sump. Is it possible that his paper filter is no longer filtering? Maybe he'll find something amiss when the filter is removed and inspected. Do you think this makes sense?

[barryh]

Hope the filter is not like this although you will have used a bendy.

Crushed Filter3.jpg (68.32 KiB) Viewed 1639 times

[ME 109]

Thanks for the discussion blokes, I'm about to head out the door to work so I'll read through your posts while I'm er...busy at work

Doesn't a remote filter with internal bypass function solve the pressure issue? Some of the filters I was looking at yesterday have varying pressure ratings for the bypass valve to open.

Bendy filter in there, Barry.

I think the white oil filter o ring would be the first thing to blow, if pressure overcame the filter?

I don't know the full story with BWJ's remote filter, and whether it is a success.