A leaking oil filter cover.

[mralistairjones]

Hello

I'm new here and seeking some advice, sincere thanks in advance to anyone who can assist me on the following.

I own a 1990 R100RS which was rebuilt and delivered to me last year.

I have noticed recently that around the oil filter cover (which has not been removed during my ownership) there is oil leaking (evident after a 15 minute rideout), not a great deal but leaking nonetheless. The attached images show what I can see. It looks to me like the oil is coming from under the area of the leftmost bolt of the filter cover and then running down to the bolts holding the underpan on.

I've completed approx. 2000 miles on the bike since it was delivered a year ago.

I am in receipt of a filter kit and I'm prepared to (for the first time) change the oil, filter etc. but I wondered if anyone could advise what may be going on under the filter cover.

Thanks in advance once again.

[Kurt in S.A.]

Welcome to the forum Mr. Jones! Here's a website that has quite a bit on the filters:

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

Nominally, the late model Airheads only required two items besides the filter in the housing - a thin metal shim and a large white o-ring. With the cover off, you probably will see something like this on my /7. What I'm pointing out on the image is the canister which is a separate part inside the engine case. It's supposed to be 3-3.5mm inset of the edge of the engine case. The cover is supposed to press and squish the white o-ring to create a seal for the filter operation.

If the distance is less than 3mm then a paper gasket might be needed. The gasket doesn't really seal like a gasket, but acts as a spacer to move the cover out so that the white o-ring isn't squished too much.

Try and remove the cover and let us know what you see.

Kurt

[barryh]

A leaking filter cover can be a sign that the filter has been incorrectly fitted with insufficient compression of the large O ring that seals the filter and ensures oil doesn't leak back to the sump instead of feeding the lubrication system.

To be on the safe side I wouldn't use the bike until this has been investigated.

They call this the $2000 O ring because it has the potential to result in needing an engine re-build due to oil starvation. If you search the web for "£2000 O ring" there is immense amount of information out there. Without doubt the problem gets over hyped but it does need to be right. If you remove the filter cover and take a picture of what comes out we can talk you through how to check if there is a problem. It's not absolutely necessary to drain all the oil to remove the filter. Put the bike on the side stand and you won't lose too much oil when the cover is removed.

This gives a good explanation of the filter arrangement with a diagram

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

[mralistairjones]

Thank you gentlemen, very much appreciate your information. I shall look to remove the cover this evening and report my findings!

Thank you.

[mralistairjones]

Good evening gentlemen.

This is what I found.

I am holding it as it came away from the engine.

[Kurt in S.A.]

So maybe the new o-ring is black! I see a gasket there as well. Generally that's not used. Do you have a picture of the filter side in the engine, like the picture I posted above? It's important at this stage to measure the canister depth to decide if you really should be using that gasket. Here's how I measured my canister depth.

Kurt

[mralistairjones]

Kurt, thank you for your reply. I do not have a picture but I shall get one in the morning.

[Kurt in S.A.]

How does the black o-ring look? Does it appear to be still perfectly round or do you see some evidence of it being squished? I would expect that the o-ring would take on an almost square shape or profile.

Kurt

[mralistairjones]

It looks perfectly round and in great shape.

[ME 109]

It appears the shim is ass about, should go in before rubber o ring.
Being ass about won't cause an external leak, but might cause an engine killing internal leak if the o ring is cut by the end of the tube.
Hmmmm, I didn't think later bikes after '85 used a shim?