OIL FILTERS

[bjamesw]

Rob, no offense taken at all.  I'm not an expert by any stretch.  I've only owned one BMW.   Is there an oil bypass valve in this engine?  At what PSI does it release pressure on the oil filter when it has clogged solid?

I just find it pretty hard to imagine that that perf tube could collapse if any sort of bypass was in working order.  Maybe we don't have one?  See what I mean.  I don't really know.   I'm hardly a mechanic.  

Are we suggesting here that the perforated metal tube is of such an inferior stiffness/gauge in the aftermarket filter that it will collapse where an OEM one will hold up?  Is that what's happening?  Sorry.  Don't be offended if I'm skeptical.   It just seems extraordinary.   Help me a little more to understand the mechanics involved here.

[Bob_Roller]

The OEM filters have a paper or cardboard perforated material around them, not the metal shown in the photo of the collapsed filter .

There's a filter bypass valve located at the end of the cavity where the filter sits, it's spring loaded ball valve .

Some BMW experts say that the bypass valve is open on a cold start, but as stated before the pressure gets quite high .

Measuring the filter canister has been recommended for some time now, just to check what you have, BMW had some quality control problems with the installation of this sleeve in the filter cavity, some were set too deep, which led to  oil pressure problems and subsequent engine damage to some bikes .

[mimmo66]

Bob,
the perforated metal is in the center of the paper pleated filter acting as a backbone to the oil filter; on the outside there's the perforated pleated paper (filtering element), and over the pleated paper filter there's a perforated paper sleeve.

The squished metal core of my oil filter was very solid, could only be bent /squished with some tool only.

If said bypass valve was not working at the time I will find out on my next oil change, although I don't know if it can be serviced from the canister.

All I know at this point is that there is a steel ball with a spring on the back acting as a resistance to the oil pressure, and when the pressure reach a certain value the ball compresses allowing the oil bypass to occur.

Domenico

[Rob Valdez 79 R65]

Re: Bypass Ball/Spring

Yes, you have one, and it should be tested on a regular basis.  Just poking the ball with a long, thin stick will allow you to judge the spring's tension.  If the spring should break, the pieces will find their way to the oil pump!  

This subject has been explored in depth on Boxerworks, and the initial and best thread is still in recovery on an old database, but these two threads should give you an idea of what is going on.

http://boxerworks.com/phorum5/read.php?3,72523

http://boxerworks.com/phorum5/read.php?3,38546,38546#msg-38546

[nhmaf]

While many may run the usual 20W-50 oil in their airheads, I generally run 10W40 in mine.  Living up here by the 40th parallel and above, I don't think there is any need for the heavier weight oil.  If I were down near Mexico, I might reconsider.    I think that the lighter oil is also less of a problem when I go out riding the the spring/fall, when the ambient temps are around 0 C.

I'd better stop now before I turn this into another dreaded oil thread.

[Barry]

While many may run the usual 20W-50 oil in their airheads, I generally run 10W40 in mine.

I'm with nhmaf on using thinner oil. What passes for summer in the UK means rarely much above 20 deg C and I have exactly the same cooling area as The 650's which means oil temperatures stay low ( never measured above 92 Deg C). I compromise and use 15W/40 and I was definitely not using 20W50 when my filter collapsed. I'd be scared to use that now in the winter.

I'll be poking the bypass valve with a stick at the next change and may put 10W40 in for the winter.

[Bob_Roller]

I use a temperature indicating dipstick as a general guide, once the oil temperature gets to 90 F. (32C.) I don't have any concerns about high oil pressure with heavy throttle usage .

With the six weeks or so of what could be considered 'winter' weather here in south central Arizona, I just keep the 20w50 oil in the bikes all year round .

                                                  

[bjamesw]

The squished metal core of my oil filter was very solid, could only be bent /squished with some tool only.

So did the oil pump, or did it not,  collapse the perforated metal tube
within that filter (the image in this thread)?  If my aftermarket filter has a perforated metal core, should I be worried about the pressure of the oil system collapsing it if the media has insufficient flow and the bypass is not working?

And I just read the following, mind bogglingly exhaustive,  treatise on airhead oil filters.  

http://bmwmotorcycletech.info/Oil.htm

Can someone please distill those vast contents into what specfically applies to the R65?  Or is it still a question of years/models?

Do we use the paper gasket supplied with the filter?  Don't use the paper gasket?  How to use the metal shim?  Snowbum writes

"28.  METAL SHIM:
    In late 1978 the factory began adding the metal shim.  It was then available separately, and the part number is: 11-42-1-336-895.  It is approximately .011" in thickness, and of diameter to match the outer face of the oil canister. No, it won't slide down into the oil pan! The earliest of these shims was made in such a way that one side had a sharp edge.  If you have one of those, the sharp side goes INwards, and contacts the canister.   The shim is installed immediately, that is, it is the NEXT ITEM,  after installing the filter itself.  The purpose of this shim, now packaged with most filter 'kits', is, as noted above, to keep the canister end edge from cutting  the critical large white O-ring, part number 11-42-1-337-098; and, to increase the pressure on that O-ring.   The metal shim DOES NOT fit against the 'cover', rather, it fits against the canister."

Say what?   And there's no diagram for this.  You don't install by putting the metal shim on the cover first?  What???    I don't see any other way to put it together?

I completely apologize for my earlier remarks about not measuring the filter depth and a few mm not making a difference.  If Snowbum is to be believed here, and he's pretty much accepted as an oracle,  then oil filters on the airheads are something of a dark art in which even sticking with OEM parts wont keep you out of the woods.  This stuff is almost scary.

[Bob_Roller]

The metal shim goes on first, then the large o-ring .

I don't know how anyone else does it, but I install the metal shim, then place the o-ring on the filter cover, seems to help prevent cutting the o-ring .

Measuring the depth of the lip inside of the oil filter cavity is how you determine  if the gasket should be used, or in a rare case, an additional metal shim may need to be installed .

[Rob Valdez 79 R65]

There are two places the metal shim can go, on one side of the large o-ring, or the other.  You want it on the side of the o-ring closest to the engine.  Furthest away from the filter cover.

The shim's main purpose is to protect the o-ring from damage.

If your canister is too far into the engine, you may need to make up for it with an extra shim.

If your canister is not far enough into the engine, you may need a paper gasket to "shim" the cover away from the engine and canister, so the large o-ring is not over-compressed.

Unless I need it for shimming purposes, I don't use the paper gasket.  My latest engine requires one.

[Mike V]

James,

The metal shim goes on first, against the canister edge recessed just inside the engine case, then the large o-ring (as Bob describes can be slipped on the filter cover).  You need to make the measurements to determine if you need the paper cover gasket. You can also tell by looking at your white rubber o-ring after it's been installed and the cover bolted down.  If it's squared off you most likely have adequate compression.  If it's perfectly round - not enough compression. It's best to make the measurements to determine what combination is best.

I prefer Oak's method, see if this makes sense to you...

If not, contact me off list I can walk you through it on the phone. It's important you understand this.

 Mike V
Senior Member
78 R100/7 Spcl., 81 R65

Posts: 435
San Diego, CA

Re: Crushed Oil Filter / O-ring Compression Criteria
Reply #27 - 03/29/10 at 22:43:45      

I wanted to share Oak's percentage formula with all those who aren't aware of it.  It's a pretty simple formula based on a target 10% to 25% O-ring compression. From an old Airmail Airtech article titled "$2000 O-Ring Revisited - Critical Installation Criteria". Oak's formula works well for me and is nice and simple when you wrap your head around it.
Basically...
O-ring + shim - cover gasket (if used) - measured cannister depth / O-ring x 100 = % O-ring Compression. Target is 10 % to 25%.


Here's my numbers plugged in from my 81 R65,
4.0 + 0.3 -3.6 / 4.0 x 100 = 17.5% (no cover gasket used)

Constants:
O-ring = 4.0 mm
Shim = 0.3 mm
Cover Gasket = 0.5 mm

As Oak states in the article "if less than 10% or more than 25% adjustments are needed. Different trials can be made with more shims or the use of the cover gasket.

As a reminder; always use a precision depth gauge when measuring your cannister depth and a good idea to check your new shim, gasket and O-ring thickness as I learned to do thanks to Barry. A check with new filter parts in the box revealed the above values to be in conformance with my measurements.  
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--------------------------------------------------------------------------------

Mike V. / San Diego
'78 R100/7
'81 R65
View my 650 restoration project at...
http://s428.photobucket.com/albums/qq8/gruntyman66/81%20R650%20Restoration/
 

[Rob Valdez 79 R65]

That is a great formula, Mike.  Thanks!

[Barry]

So did the oil pump, or did it not,collapse the perforated metal tube  

I believe what happens is that the filter pleats kink then start to fold flat which significantly reduces the filter area which means more pressure drop across the filter until it collapses the inner support tube.

I also believe that a contributing factor to kinking of the pleats might be too much axial force resulting from improper shimming. I had been leaving out the paper gasket.  When changing filters they were coming out with the pleats slightly kinked even when the filter hadn't collapsed.  Variation in length of the non OEM filter won't help.

Should it be impossible to collapse a filter if the bypass is working OK ?

That's why I'm going to poke that valve with a stick at the next oil change.

Here's my own calculations on the need for shims and gaskets. My tip is that as well as measuring the canister depth also measure the thickness of your own gasket, shim and O ring then use those figures in your deliberations.

[bjamesw]

Thanks for all the info here everyone.  It appears that I've been regularly placing the shim incorrectly for many years.  Since no instructions came with filters it seemed to make perfect sense to put the shim over the extended portion of the cover, where it fits a bit tightly but otherwise where it seems intended,  with the oring over it.  Now that I'm stopping to think about it, the shim makes little sense here.  All the while I've had it on the wrong side of the Oring.  But the Orings I've replaced with each filter have always been squared upon removal and never torn, pinched, or shredded.  Basically then, despite placing the shim incorrectly, I've been lucky in not needing it in the first place.

As far as the inner perforated tube collapse is concerned,  there seems to be no "right" or "wrong" on this, but a little of both.  Here are a couple of posts on a thread from another forum on this subject...



      
Diagnosing Engine Oil Filters With Collapsed Center Tubes

When a collapsed center tube or element is discovered, the natural tendency is to assume something is wrong with the filter (Fig. 1). This is not the case, but is a symptom of problems with internal engine components.

Most engines incorporate within the oiling system a by-pass valve across the inlet and outlet of the full flow oil filter. The valve is designed to open and by-pass oil around the filter and/or element when the restriction reaches its opening pressure (Fig. 2). The by-pass flow circuit insures oil flow to the engine when there is a significant restriction across the filter due to plugging or cold start conditions. Typically, engine manufacturers design by-pass valves to open at a pressure differential of approximately 10 to 30 psid with some as low as 4 psid (28 kPad), with some opening as high as 75 psid (500 kPad). Some engine manufacturers have the by-pass valve located in the filter mounting base on the engine, while others locate the valve in the filter. Either way, the same purpose is served.


more here
http://www.filtercouncil.org/techdata/tsbs/88-3R2.html

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When they were new motorcycles, many /7s collapsed their OEM filters in cool weather and/or when the motor was revved with the motor cold. To combat this, a reinforcing ring was installed in the center of the standard filter.

The hinged filter does not require this because it's sections are so short, effectively giving it reinforcement in two places.

The oil pressure relief valve can only pass a small quantity of oil, which must first get past the camshaft front bushing ('70-'80) and front main bearing.

The filter bypass may open in cold conditions, but it, too, has a rather small opening. The bottom line is to be gentle with a cold engine, especially when using a high viscosity oil.

If you are using aftermarket filters, check whether they have the reinforcing ring in them.

[Barry]

If you are using aftermarket filters, check whether they have the reinforcing ring in them.

Hiflo filters do not have the reinforcing ring.