Oil Leak from vent in cam reducton cover

Was continuing my attempt to run down a oil leak and I think I have found the cause but I do not understand what could be causing it. When I replaced my timing belt I had to remove the left side cam reduction cover, the cover behind the timing cog on the left side of the engine, to get the water pump out. When I replaced the cover I installed a new oil seal and gasket.

Now I have oil coming out of the small vent hole in the back of the cover, dont understand where this oil is coming from and what is this vent hole venting? The oil is working its way down the timing belt cover and exits around the clutch cover. I had thought that was my problem so replaced the clutch cover gaskets but when the leak persisted I started working my way back through what I had removed for the belt replacement and found this issue. There is no oil in the area of the timing belt, it is dry and clean, it is just leaking down the back of the cover (outside the engine) until it hits the rubber seals where it then follows them to the bottom of the timing belt cover.

Was wondering if anyone would have any ideas before I start pulling plastic and draining the rad. Am ok with replacing the oil seal in the cover again if it is needed but want to make sure there is not any thing special that needs to be done before doing the replacement and having the same problem. There is a note in the manual about not driving the seal to deeply so it does not block the vent but again I dont know what it is venting and how oil would get in the area being vented.

Any wisdom would be appreciated

Greg D
STOC906

I may be misunderstanding your description, and my memory may be bad regarding those parts, but AFAIK the cam reduction cover has no oil seals, those are only dirt/dust seals. There was a thin paper gasket in back as I recall, is that where its leaking from? Sorry my memory is bad, but I'm having trouble visualizing where oil would be leaking from that area, because as you say, there is no oil generally in that area. I'd check the valve cover gasket first, is it possible that is the source of the leak, given where you see the signs of oil?

Also, maybe a picture of the leak area would help.

all mating surfaces need to be cleaned. that's the engine, gasket, and plastic of the cover. I like using brake cleaner since it's pretty safe to use on plastics, and disposable toilet paper ( lol , ever run across perm. toilet paper?) the gasket I just take outside, douche and shake off excess. and let all dry. then apply a light coating of "non-hardening gasket sealant to ALL mating surfaces. IIRR there's one part of the engine surface that took me using a small coffee stirrer to get the sealant down into a recess and a q-tip for the cleaning on the engine side ( last time I did this I think I used permtex blue silicone based sealant - it should state "non-hardening" on the tube- but any brand would probably make do) the gasket that runs around the perimeter is not normally replaced, unless if it's damaged. after it's set up for a few hours, you can trim off any excess sealant on the outside of the engine

+1 on a picture of this vent. TIA

I will try to get a photo later this week as I am working on shift this week. If you have a copy of the Clymer st1100 repair manual on page 132 (section 4, Cam Reduction gear assembly) there is a photo (photo 77) of the Cam Reduction Cover and a section describing the replacement of the oil seal. There is a oil seal in the cover as it keeps the oil that is flooding the bearing at the end of the cam reduction shaft out of the area that the Timing Belt runs since the Cam Reduction Shaft is what the gold driven pulley connects to for the timing belt (left side that is held in place by the silver pulley guide). There is also a photo on page 130 (photo 70) that shows the seal and if you look close you can see the vent.

In photo 77 you can see the oil seal that is installed (A), and the vent in the cover (B). The oil is leaking from this vent.

The oil is not leaking from the gasket between the cover and the head as the oil line starts below the vent hole which was verified by using talc to verify the source. Cleaned the area placed a piece of cloth tape under the vent and took the bike out for a ride. The oil came from the vent after the engine was up to speed, can not see the area while riding so can only tell the flow volume from the amount on the cloth tape.

I also checked the crankcase vent and vent line to make sure they were not blocked causing any additional pressure.

Hopefully you can see the area from the manual as I was also surprised that there was a vent in this area as I can not figure out what area is being vented. Nothing special when I replaced the seal, old one came out and new one was driven in.

Again thanks for reading and for any assistance you can send my way.

Thanks

Greg D.
STOC906

I don't have a Clymer, but looking at the Honda and Haynes manuals I'd say you somehow damaged the reduction shaft holder oil seal. The Haynes says to replace the seal if there's any sign of oil leakage in the front of the holder. Makes sense to me as the source in that area.

John
via iPhone 4S

OK, I get it now, you replaced oil seal #34 on the attached fiche screenshot when you had the cam gear off the first time, and now its leaking from that seal. Seems like no other option than to replace the seal again.

Thanks everyone, that's what I suspected that I would have to do anyway but was hoping I missed something that was easily correctable. Now I need to order the parts as our local Honda dealer closed their doors.

Again thanks

Greg D.
STOC906

Just a quick follow up to close out the post. Last weekend was able to tear the bike down and pull the Cam Reduction Cover and sure enough the oil seal was folded over in one spot. Don't know how I did it when installing it over the Cam Reduction shaft but was glad it was as blatantly obvious when I pulled the cover.

When I pulled the timing belt covers it was interesting how the oil leaking from the cam reduction cover worked its way down the seals of the timing belt cover all the way to the clutch cover.

Completed the repair and dry as a bone so the old girl is good for another 90,000 miles. So again thanks for validating that this was the most likely issue and that I had not missed something.

Greg D.
STOC906
1995 ST1100 - RIP
2001 ST1100

Thanks for the follow up, Greg! Always appreciated, especially by those of us 'invested' in your issue. Glad to hear it's fixed. Now GO RIDE!*

John
via iPhone 6
*Official STOC motto.