Oil Pressure

[Roy Gavin]

Straight 40 oil goes back to the days when bikes had roller bearing cranks and didn't have oil filters, and is plain wrong for your bike.

So no point in checking anything else until you get it out of there and put the correct oil in.

[bbelk]

get it out of there and put the correct oil in.

I suppose I will do that today, but the sun has not come up yet. My R65 has the same oil in it. It is not due for changing and has not caused a problem, but I suppose I will do that one too.

[barryh]

Crushed oil filters and oil pressure low enough for the oil light to come on are not necessarily related. A completely flattened filter came out of mine without the oil light so much as flickering even at warm idle. As I understand it oil will just bypass the filter like it's supposed to so the risk is from unfiltered oil and maybe slightly lower pressure than usual but not the few PSI that the oil switch is set at. With the filter out you might want to give the bypass valve at the bottom of the canister a poke to check it moves Ok.

Filters of all types have failed in the past including so called genuine BMW ones back in the 80's when they changed supplier.
Still best to use a quality item and go easy on the revs from a cold start. I believe I went wrong on both counts. Personally I decided never to use anything as thick as 20W/50 oil at sub zeo deg C temperatures and use 15W/40 instead.

Straight 40 is OK in a hot engine but far thicker than 20W/50 from a very cold start so I'm suprised your filter was not as flat as mine.

[Rob Frankham]

OK, lets look at this logically... Most boxers use the same filter (more or less) and by far the majority don't suffer from collapsed filter elements. The probability, then, is that the problem lies in those bikes that do (yes, I know that's stating the obvious) so we can pretty much rule out defective elements. This leads to pretty much one conclusion, thay is the pressure differential across the filter is too high... not necessarily all the time but certainly frequently enough to screw up several succesive filters.

There is an excess pressure relief valve located at the inner end of the filkter canister that should vent any excess pressure across the filter. This should be sufficient to prevent the filter collapsing. If this is stuck or blocked, then there will be nothing to stop pressure building up.

I can nthink of no other reason why pressure across the filter should build to that level, no matter what else is wrong with the engine. That's where I'd start.

Rob

[barndeadr80]

Went there, checked that. All the ideas and checking went nowhere on mine as far into it as the other pressure relief valve. Some time and a reciprocating saw might eventually find and answer.
Plan B: Ride it til it fixes itself in some holistic way, or until it blows.
Two of my filters were like the pic above when they came out.
There is something very real occuring in there and it is infrequent or overlooked/ignored.

[bbelk]

I'm suprised your filter was not as flat as mine.

My bike has a tube down the center of the filter that prevents a total flatening of the filter. If you look at the picture on the first post the inner metal on the filter looks square. It could only crush that much before hitting the more rubust tube done the center.

[mattcfish]

Went there, checked that. All the ideas and checking went nowhere on mine as far into it as the other pressure relief valve. Some time and a reciprocating saw might eventually find and answer.
Plan B: Ride it til it fixes itself in some holistic way, or until it blows.
Two of my filters were like the pic above when they came out.
There is something very real occuring in there and it is infrequent or overlooked/ignored.

If the relieve valve is good then the relief oil passage could be blocked with something (god knows what).
To test this, remove the relief valve spring and ball and see where your pressure is. The pressure should drop. If not there's a blockage.

When cold these pumps put out well over 100psi, my pressure gauge pegs when I start up. 40w is too heavy.

[Deleted User 287]

I am curious why you put straight 40w in there, Brad.

[barndeadr80]

Well, instead of dicking around removing the detent ball and all, I blew air through there. It was clear. And yes, the gauge screwed into the block was educational. Lots of difference hot and cold with the 20-50.
The tube down the center of the filter is not the answer to the problem, but it sure is nice to know the filter can't go flat like the full length ones did and hopefully the hinged ones won't fold in, rupture and puke filter and aluminum bits into the block. I'll take a squared one like bbelk's over a flat one or ruptured one any day.

[barryh]

I've not heard of people have successive filters fail before and having had only the one flattened filter I am fairly determined it won't happen to me again. I hold my hands up to over reving a cold engine though it's a fine line between lugging and over reving when you have a hill to climb after the bike's been stood out all day in the winter.

Filters don't seem to collapse in other vehicles and I'm not sure I'm convinced that a small number of our engines have faults that lead our filters to fail. The bypass valve should be opening briefly every time we start a cold engine. Maybe because we have a high pressure high volume lubrication system the filter strength is a bit marginal so we just have to take more care to do things right. Filters have occasionally been flattened since the bikes were new. In the Sept 1980 journal of the UK BMW club there were 5 letters reporting BMW supplied filters having collapsed. Too many perhaps to believe it was not related to filter quality and a recent change in filter supplier or a bad batch of filters.