Oil filter depth gap: The $2000 O-ring.

[datchew]

I'd like to continue with new info on that but cannot find the old thread.
Please advise if you have it. Otherwise, i'll continue this new one.


If you haven't seen Matt Parkhouse's article (Matt's in the hospital right now by the way so if you're the praying type... you know what to do.) in the BMOMOA March 08, or if you haven't seen the other thread, here's a quick summary.

If you take off your oilcooler cover plate, and measure the gap from the face of the filter to the flat machined surface of the engine case, it should be 3mm. Pics in magazine, and my own to follow. Maybe tomorrow i'll upload them.

Matt states that your white O-ring should be squished to look kind of square in its cross section after service if it was installed right.

You are supposed to use the metal ring shims to adjust closure of this gap to 3mm.


NEW DRAMA:

My gap during an oil change today (measuring the old filter) was 5mm approx.
No need for panic. She's running fine. Time to shim.

I put in the new filter and the gap was different! It was 4.3mm. So I pulled out both old and new filters and a vernier caliper and measured length of each entire unit (squeezing together to seat hinge in the middle).

Then I measured each can segment (metal end to metal end) separately and guess what. Same part #. Same "made in austria" but they were off by approximately 0.6mm. That's what I call a manufacturing process out of spec.


So, word to the wise. Get a vernier caliper and measure each oil filter.

I ended up putting 3 shims in with the new filter which brought my gap down to 3.4Xmm and made it so that without the aid of the screws, I could not just push on the cover to make it compress enough to lie flat against the engine case. So, I feel like i'm safe with the 3.4mm.


Now, I measured 5 shims (that's all I had) and all of them measured exactly 0.28mm, so i'm guessing it's safe to state that this is the correct shim thickness.

[AliBaba]

I wouldn’t recommend using more then one shim; solve the problem not the symptoms…..

Why do you measure the length of the filter?
The filter has big o-rings in both ends; it has to be a lot out of spec (several mm) to make any problems. It’s the canister depth that counts.

Puking oil: http://www.advrider.com/forums/showthread.php?t=211923
Shimming oil filters: http://www.advrider.com/forums/showt...=286618&page=1

[beemer67]

I agree with the above writer, that length of the oil filter is really not of any interest. It has no bearing on anything. But, adding multiple shims IS solving the problem caused by the symptom of erratic factory placement.

What datchew said first was the important thing. Depth of the cannister in the engine block. This was also written up very clearly by Oak in Airmail this January.

The cannister is supposed to be installed at the factory to a depth of 3mm. But subsequent measurements by many people have shown this figure to be all over the place.

My friend's '77 RS measured at 2.9, he was finding his O-rings and shim were really looking mangled after every change. He has started re using the paper gasket, that everybody has now stopped using.

I just measured my '81 G/S this week and found I was at 4.2mm. I have now put in 3 shims.
The recommended compression value for the O-ring should be between 10 and 25%.
A new O-ring should be 4.0mm exactly.
A new shim is 0.30mm
My formula for 3 shims is : 4.0(o-ring) plus 0.9(3 shims) minus 4.2(my depth) equals 0.7 divided by 4.0=0.175 times 100=17.5%
This seems to be within the ball park.
Prior to this there was a risk of low pressure with just one shim as my percentage was 2.5%. I have been lax in reusing my O-rings as they always came out looking like they went in. And as I now realise it was because they weren't being compressed.

Datchew with 3 shims has a compression of 15%, so he could go to 4 shims if he wanted to.

Chris

[AliBaba]

I agree that using multiple shims are better then doing nothing.
According to two of the best engine-builders in Germany (HPN and Motoren Israel) this is not good practice.

If the gap is big it’s probably because the canister has moved, and it will probably happen again. When you add shims you increase the risk of a moving canister.

Link from Motoren Israel: http://www.motoren-israel.com/produc...-erneuern.html

[Joerg]

Originally Posted by AliBaba

I agree that using multiple shims are better then doing nothing.
According to two of the best engine-builders in Germany (HPN and Motoren Israel) this is not good practice.

If the gap is big it’s probably because the canister has moved, and it will probably happen again. When you add shims you increase the risk of a moving canister.

Link from Motoren Israel: http://www.motoren-israel.com/produc...-erneuern.html

... and from the Tips'n'Tricks thread: http://www.advrider.com/forums/showp...9&postcount=67, in particular the link to the PDF on the HPN website.

[AntonLargiader]

With typical dimensions, the canister bottoms out around 4.2mm. It's inserted to some other depth and sometimes gets pushed deeper.

O-ring compression isn't as simple as most people seem to think, as the O-ring is already compressed radially before it's compressed axially by the cover. By my figuring, it is fully square around 3.5mm canister depth.

Adding shims is an OK solution (seems to work) but I don't like the idea of having multiple steel surfaces forming a sealing barrier against the oil pressure, so what I do now is pull out the canister and install a new one with a shim underneath to give a solid 3.5mm depth. Then just use the white O-ring, no shim, no gasket, no worries.

Lots of numbers on my canister web page:

http://www.largiader.com/tech/filters/canister.html

Personally I think 3mm is too shallow, especially for the later canisters with the wider lip. There's nowhere for the O-ring to go, so it pushes the canister in (IMO). I've never seen 3.0 in a BMW bulletin (but I have seen 3.1~3.8).

[AliBaba]

Shimming at the bottom of the canister is a good solution. In fact it was my original plan when I had 4.6mm clearance but when I removed the canister it got some cracks and a friend made me a replacement with the correct length.

[mark1305]

datchew, could you be confusing the filter element with the term cannister? That happened to me for a while.

As others mentioned, the length of the filter element isn't the issue with the o-ring, but the cylindrical insert inside the filter cavity.

When I first got my airhead late last year, I read all I could on the subject and still confused the term cannister with the oil filter element itself. I finally understood the cannister was the round cylinder pressed into the crankcase. And when I measured it at 3.1 - 3.2mm deep, I was happy.

I'm with Anton on not being comfortable with using the shim to seal against the metal surface. When I went through my bike, the cannister measured OK, but the previous oil changer had used one shim between the cover and the o-ring, and the paper gasket under the cover. This had the o-ring bearing directly on the edge of the cannister which made a nice even indent in the 0-ring, so I knew it had been reasonably well sealed. But just about everything I'd read says to put the shim in first against the cannister, then o-ring and then cover, sans gasket, unless the cannister depth is less than 3mm. And that all makes sense to me, except for the concern about trusting a metal shim to seal on the end of the cannister. On the other hand, after looking at the groove in the o-ring I removed, I can see real potential for the o-ring getting sliced during assembly if it shifts the least bit.

One of those damned if you do, damned if you don't situations.

[datchew]

Ok.

1 - I was confusing cannister with filter. I'll re-measure.

2 - The filter length DOES directly affect o-ring. Look at Anton's diagram. The filter presses against the black square o-ring which presses against the cover. If the filter is too long, this moves the cover outward which effectively reduces the pressure (or increases the opening) for the white o-ring.

3 - My white O-ring appears unblemished when I took it out, so even if I measured wrong, i'm close to the danger zone.

4 - What is the procedure for the "remove cannister and put shim BEHIND it" mod?

Anton, thanks again for the great website. I didn't see that article before (seems a trend, no?).


Joerg. Forgot your tips and tricks blurb. Pretty much sums it up.
http://www.advrider.com/forums/showp...9&postcount=67

[bmwblake]

you'll notice in matt's article that due to inflation the 2k oring is now 3k.

[AntonLargiader]

Originally Posted by datchew

If the filter is too long, this moves the cover outward which effectively reduces the pressure (or increases the opening) for the white o-ring.

The clamping force of the three screws will easily crush the filter. That cover will sit flat against the case no matter what. And the filter doesn't hold any pressure. The sealing thing is simply a function of the cover vs. the canister, which boils down to the case vs. the canister (once you take the cover gasket out of the picture).

[AntonLargiader]

Originally Posted by bmwblake

you'll notice in matt's article that due to inflation the 2k oring is now 3k.

If you buy a new crank, maybe. Good used cranks are available for a few hundred dollars. Crank, mains, conrod shells, I'll do that for $2000 all day long.

[jtwind]

I thought one of the reasons for the shim was to protect the oring from the edge of the filter?

[datchew]

Originally Posted by AntonLargiader

The clamping force of the three screws will easily crush the filter. That cover will sit flat against the case no matter what. And the filter doesn't hold any pressure. The sealing thing is simply a function of the cover vs. the canister, which boils down to the case vs. the canister (once you take the cover gasket out of the picture).

I see your point and it makes sense now.

What about #4? Is that a trade secret?

[AntonLargiader]

Originally Posted by datchew

What about #4? Is that a trade secret?

You feelin' lucky today, punk?


EDIT: OK, here's how.

1) remove canister
2) insert appropriately sized shim
3) install canister.