Oil Leak

[yellowjacket]

I have an oil leak I can't seem to track down. I replaced the oil pan gasket and the leak does not appear to be coming from there. The leak seems to be coming from the left side. I have checked everything on the left nothing appears to be leaking. It is a pretty good drip. Could it be coming from the starter motor?
Thanks

[yellowjacket]

This is where it seems to be leaking from. Right in front of the shifter. Why would be dripping out of that hole?

[Rich82GS750TZ]

That, I believe is a weep hole from your starter motor cavity. Take the starter motor cover off and see if it's wet in there. You won't likely be able to remove the starter motor itself without getting the carbs out of the way (and we all love doing that). The stator swims in oil. There is a seal on the end of the starter motor shaft where it enters the stator area that should keep oil from getting into the starter motor cavity. Of course, this is all just speculation. We don't even know if you're talking about a motorcycle or a dump truck. If it is a motorcycle, please put your bike year and model info (at a minimum) in a signature. It's in settings.

[Nessism]

That's the drain for the starter cavity. Maybe starter O-ring or cam chain tensioner leak?

[yellowjacket]

It is a 1980 GS850. The bike is awesome and fun to ride. The oil is a mess. Thanks for the input. I will start with starter seal.

[Rich82GS750TZ]

Welcome to the forum.

[bwringer]

Congratulations! You've found the Mystery Hole!


Yep, the leak originates from the o-ring on the nose of the starter. 100% of GS motorcycles will leak from this o-ring if it's not replaced. After 30+ years it's glass-hard and probably cracked.

And if your cam chain tensioner is leaking (and they also all leak until re-sealed) the oil will end up leaking from the Mystery Hole. Oil pressure sensor leaks are less common, but can also end up sending oil into the Mystery Hole.

My instructions for rebuilding the cam chain tensioner:

https://www.bwringer.com/gs/camchaintens.html

Removing the starter to replace the o-ring is pretty easy, and can be done without removing the carbs. Remove the cover, remove the wire and the two bolts securing the rear of the starter, gently pry it to the right a bit, and remove. When replacing the starter with a new o-ring installed, it will need a little push to compress the o-ring, and it takes some finagling to get the install depth just right so the bolts will go back in.



I started calling it the Mystery Hole because it's a common question from new owners, and often a total freakout... OMFG I found a BIG HOLE in my ENGINE, and OIL is LEAKING!!!!!

At least you didn't try to plug it with a wad of JB Weld... It's a much needed drain for the starter cavity so that water doesn't accumulate.


Here are a couple of shots of a junk GS850 engine showing a piece of tubing shoved through the upper and lower Mystery Holes to illustrate:




FWIW, the gear position switch you see near the bottom right of this photo is another common GS leak point that's also very easy to fix by replacing the o-ring. You'll need a long screwdriver or a long bit on your impact driver to get the screws. Just watch for the little spring-loaded contact pin. I always replace these screws with socket heads.

[bwringer]

Also, for future reference, technical questions should be posted in the appropriate technical area, in this case the "4 Cylinder Engine/Drivetrain/Clutch" subforum, not in this general discussion area. You'll get a better, faster response in the proper subforum.

It's also a good idea to put your bike's info in your signature, that bit of text that appears after your posts. You can change that here:

https://www.thegsresources.com/_forum/profile.php?do=editsignature

That way, we know what sort of conveyance is under discussion without needing to ask. In this case, the Mystery Hole and starter o-ring are pretty universal in GS engines, but for most discussions year and model make a big difference.

[yellowjacket]

Thanks for the input on the leaks. I replaced the o-ring on the starter. I could remove the starter with out removing the carbs but I had to remove the carbs to put it back in. I could not get the holes to line up to re-install the bolts. That was ok because I cleaned up the area real well to look for more leaks. Put it back together and it started right up. Noticed some leaking from the oil pressure switch(thanks Bwinger for the picts). Tried tightening it and it moved easily. Leaking seem to stop. What is the right approach with the oil pressure switch?

[bwringer]

What is the right approach with the oil pressure switch?

Order new o-rings from yer favorite Suzuki bits shoppe. There's a round o-ring around that nylon bit, and there's an oddly shaped one that seals the body of the switch.

https://www.onlinecycleparts.com/oemparts/a/suz/50d4015af8700230d8b4e48f/crankcase

#57 and #53 on this diagram

[Chris Bock]

Just bought an '80 GS1000G. When I went to pull the gear switch, oil gushed out until I screwed the switch back in. That's not normal, right?! What is the culprit and how do I fix it?
The PO installed a new petcock and flooded the case with fuel... And lit all of the wiring on fire. Replaced the wiring, but the switch itself isn't working.
Searched the forum, so apologies if I missed this topic.

[bwringer]

Just bought an '80 GS1000G. When I went to pull the gear switch, oil gushed out until I screwed the switch back in. That's not normal, right?! What is the culprit and how do I fix it?
The PO installed a new petcock and flooded the case with fuel... And lit all of the wiring on fire. Replaced the wiring, but the switch itself isn't working.
Searched the forum, so apologies if I missed this topic.

That's pretty normal. I'm pretty sure the gear selector switch is "underwater" when the oil is at the proper level and the bike is on the center stand. With the bike on a kickstand, you will lose a lot more oil. Note how the stator is higher up -- you can replace the stator with the bike on the centerstand, but you have to be ready to lose about half a cup of oil.

I'd replace the o-ring (or leave it until the next oil change if it's not leaking) top up the oil (near top of sight glass with bike on centerstand), and carry on.

As far as the switch not working, this is just a guess but there's a spring loaded steel nubbin under there sitting in a hole in the end of the shift drum. If the nubbin went gesproinging away in the gush of oil, the switch won't work. The spring might have jumped out too. It's a very simple switch; the nubbin grounds against the assorted contacts in the switch body to indicate the position of the shift drum.

Poke around in your drain pan or floor... if the nubbin and/or spring are truly lost, the bike will still work fine but you won't have gear or neutral lights (there's not an out-of-neutral ignition cutoff on these bikes).

[Cipher]

Gear position indicator switch?
Had mine out once lost oil.

Be careful fine screws and well aged baked plastic are prone to failure treated roughly.

[Chris Bock]

Thanks! I drained the case (reused the oil. Gonna do a few more changes to flush out the gas and re-lube everything) and pulled the switch. Sure enough; the contact nub was missing. Strained the jugs of oil/fuel that came with the bike, and found it! Spring was still in place, and after installing the contact and switch, everything functions great!
Thanks again!

[Rich82GS750TZ]

Chris
Nice job. I find it amazing that you found this hiding in a jug of oil that came with the bike.



Now,
Let me say, Welcome to the forum. How's about you go to the GS Owners Forum and properly introduce yourself and your bike. I't's nice to have a signature that shows at least your bike(s) year(s) and model(s). Go to settings at the top right of any page.

We also like pictures (that can be a little more complicated)