1978 R100/7 and that annoying oil filter/o-ring issue

[boxermaf]

I've been digging into the 'new' 1978 R100/7 which I bought late last year. The seller said that he had changed the oil and oil filter fairly recently. When he started the engine for me oil started to leak out of the oil filter cover. He snugged the cover bolts a bit more and it seemed to stop, so I took it for a short test ride of 3-4 miles. After I trailered the bike home, I started it up and rode around our driveway for a bit, and noticed much more oil coming out. I parked it and didn't run it after that. The oil light didn't come on while running - and I think that it still works, so maybe engine is still OK.

Fast forward to now... I've discovered the problem(s), or rather, the causes of the problem:
1. Canister Depth is very shallow - I checked it in (3) different locations and averaged the measurements and come up with 2.7mm
2. The PO installed a long style filter and didn't use a metal shim. The 1978-bikes have a sharp edged canister and the O ring was shredded in several places.
3. The inside tube of the oil filter was crushed flat.

I've checked the check valve at the base of the cannister and it is working, or at least operates when pressed with a long screwdriver tip. I've got a new hinged oil filter kit (no oil cooler), so:

1. Based on the shallow depth, I'm going to need to use, I believe, (2) paper cover gaskets - using just one seems to try to overly compress the white o ring with the metal shim in place. I get the cover screws cranked down fairly tight and the cover still doesn't seem to be squeezing the cover gasket - I can wiggle/move the gasket with my fingernail still.

2. If I double up and use (2) paper gaskets, I think that the cover and paper gaskets are pretty well snugged down with similar torque applied to the cover bolts. Based on the calculations:
2.7mm (cannister depth) - 0.3mm shim thickness + 0.45mm gasket thickness + 0.45mm gasket thickness = 3.3mm depth

The 4mm wide o ring is then compressed about 18%. I think this is OK. If I go with just 1 shim though it will be compressed almost 30%, but I don't know if the cover will be tight enough to the gasket and case to avoid leaks.

3. I am hoping that the oil filter inside being crushed doesn't imply that the oil filter flow through the inside of the filter was non existent due to pressurized canister and leaking/torn o-ring condition. Ugh.

This 1978 bike seems to have alot of 'oddities' with it. I read that Anton Largiader also measured very similar shallow cannister depths on another 1978 R100. I am thinking that 1978 was not a good quality control year at BMW...

 

[20774]

BTDT...my canister depth is 2.8mm...pretty close to yours. I use one shim, one o-ring, and one gasket. The calculated compression of the o-ring is 25%...pretty good. If I substitute your 2.7mm, I get compression of 27.5%...creeping up a bit. In your case, you said you used 2 gaskets...that drops the compression to 15%...starting to get marginal but is probably better than going higher in compression. I think Oak has written that it should be between 10 and 25%.

In the case of our /7s, the gasket really does very little in the way of preventing leakage as we think of how gaskets might work. Consider the situation where the canister depth is 3.5mm or so. In that situation, you would use no gasket and there would be no leaks around the cover. That is because the o-ring is doing all the sealing.

So for our situations, the gaskets are merely spacers, to control the compression on the o-ring.

 

[ccolwell]

If the oil light didn't come on, you're fine. When I had this problem on an '84 R100, the light did come on while I was out riding. I borrowed a quart of oil from a passing motorist, bought another a few miles later, and dropped the bike off at a shop while I went come and got my truck. I rode that bike another 10k without any signs of damage, no power loss, increased (or any) oil usage.

 

[rozemab]

look here:

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

 

[6659]

Don't bet on the oil warning light. On my bike, that was the only area with an electrical problem. The socket was oxidized and the light could not come on. Simple check is to look for the light when the igntion is on and disappears when the bike is started.

 

[boxermaf]

The oil light does work - but it didn't illuminate while the bike was running and doing its oil spill impression. But, the oil filter tube (inside) was crushed which also causes me to worry. Could that have caused a pressure spike that damaged the o-ring? Or did the o-ring failure cause the oil filter tube to collapse? Or are they totally unrelated and I'm just really "lucky" to get both of these at once? I pulled the oil pan off today and things actually look good in there - no metal chunks, shards, or even any "fuzz". Not much "sludge" either, though old gasket appears to be molecularly bonded to the pan - it is soaking in acetone overnight as the application of torch and razorblade was making little headway and I don't want to gouge the pan. I'll put the new gasket on the pan (it was leaking), fill'er up with oil and see how it runs (and if the leaks have stopped).