Oil leak coming from LH crankcase area on 1150 bottom end

[John Kat]

I have an 1150 bottom end on my 1100 Kat and discovered that there is a small oil leak on the left hand side of the engine.
It could be the gasket of the LH crankcase cover but I noticed that there is also some oil around the starter motor?
I suspect the oil could be coming along the shaft of the starter motor if the crankase cover gasket had been damaged or cut in the area where the alternator wires are routed?
Doesn't sound quite clear but I hope you understand what I'm talking about.
I will open it up to determine the issue.

[The1970's]

I had the same oil leak and it turned out to be a combination of the starter O-ring and the cam chain tensioner leaking and running into the area under the starter. Otherwise I would look at the cover gasket

[John Kat]

I had the same oil leak and it turned out to be a combination of the starter O-ring and the cam chain tensioner leaking and running into the area under the starter. Otherwise I would look at the cover gasket

I had forgotten there was an O-ring behind the starter...
Thanks!

[bwringer]

I had the same oil leak and it turned out to be a combination of the starter O-ring and the cam chain tensioner leaking and running into the area under the starter. Otherwise I would look at the cover gasket

Yep. Both are very, very, very common. As in, every GS will suffer these issues. So I guess "universal" would be a better word.

Fortunately, both are also relatively easy to deal with, too.

I don't know whether the GS1150 has the same "Mystery Hole" as other GS engines, but this is where oil from these sources usually ends up. The Mystery Hole is the exit point for the drain hole at the bottom of the starter cavity. The drain hole is needed so the starter doesn't sit in a pool of water when it rains.

Here's the Mystery Hole on a scrap GS850 engine. The blue tubing is only there to show they're connected:




I call it the Mystery Hole because of the panic and puzzlement it often causes when a new GS owner spots the drain hole for the first time; "OMFG! There's a HOLE in my ENGINE, and OIL is LEAKING OUT!!!" Hopefully they check on the GSR forum for the real causes before jamming a wad of JB Weld in there...

[John Kat]

Yep. Both are very, very, very common. As in, every GS will suffer these issues. So I guess "universal" would be a better word.

Fortunately, both are also relatively easy to deal with, too.

I don't know whether the GS1150 has the same "Mystery Hole" as other GS engines, but this is where oil from these sources usually ends up. The Mystery Hole is the exit point for the drain hole at the bottom of the starter cavity. The drain hole is needed so the starter doesn't sit in a pool of water when it rains.

Here's the Mystery Hole on a scrap GS850 engine. The blue tubing is only there to show they're connected:




I call it the Mystery Hole because of the panic and puzzlement it often causes when a new GS owner spots the drain hole for the first time; "OMFG! There's a HOLE in my ENGINE, and OIL is LEAKING OUT!!!" Hopefully they check on the GSR forum for the real causes before jamming a wad of JB Weld in there...

Yes, there's the same "mystery" hole on the 1150!
I replaced the O-Ring from the starter and hope it will fix the issue?
Well it didn't fix it totally!
There is far less oil coming but I've identified the source!
In fact the oil comes along the alternator wires that are routed next to the starter motor.
I need to pull the LH crankcase cover off to see what's happening...
I wonder if this is not due to excessive pressure buildup in the crankcase as the engine went from the maximum oil level to minimum in about 250 km!

[John Kat]

The oil leak is fixed!
I changed the gasket of the LH cranckase cover and no more oil leak.
In fact the PO had not properly positionned the rubber gasket that feeds the alternator wires.
On top of that he had cut the paper gasket to feed the wires through...
I know he had changed the starter motor and he must have butchered the gaskets underway!

[aaronc70]

thumbnail_20181119_180034.jpgI've just inherited my father-in-law's 1979 GS1000 (GS1000E I believe) and it is pouring oil from the hole in the bottom of the starter housing (see pic). I'll be checking the starter drive O-ring soon, hopefully that's all it is. But once I get this sorted out, does the hole just remain a hole or is there some sort of tube that needs to be inserted and routed underneath the bike? I don't see an entry point back into the crankcase like on the picture here of the GS850. And I don't see any mention of it in the parts fiche or Service manual. Any help is appreciated!

[Big T]

The hole is just a hole, no tube needed

The process is to start at the starter o ring, if it still leaks, rebuild the camchain tensioner, then replace the valve cover gasket (which you should do when you adjust the valves)

[aaronc70]

BT, excellent! Exactly what i needed to know. Thanks did the reply!

[aaronc70]

Changed out the single O-rind at the starter/crankcase interface, and after one solid heat-cycle, it seems to have fixed the problem. The old O-ring appeared intact, but a new one from my Harbor Freight O-ring kit seems to keep the oil out of the starter encasement. Thanks for your help again.

BREAK
I may have one more slight leak at the Oil Pan (that covers the sump filter). I'm guessing I'll need to remove the exhaust on this GS1000 to have enough clearance to remove and replace that gasket? Can anyone speak from experience? Any special tools needed to remove the exhaust?

[John Kat]

BREAK
I may have one more slight leak at the Oil Pan (that covers the sump filter). I'm guessing I'll need to remove the exhaust on this GS1000 to have enough clearance to remove and replace that gasket? Can anyone speak from experience? Any special tools needed to remove the exhaust?

I had this issue on an 1100 kat and it turned out that the oil pan had a slight crack probably due to the PO dropping the engine on a hard surface...
It cost me two oil changes!