Sudden oil loss

A while back I was going to go for a ride after my Seca sat for a couple weeks. Didn't want to start right off, so I put the petcock on prime and tried again...went for a ride, topped off the gas and parked. A week or two later, I looked in the garage and discovered that I'd not turned the petcock off prime, and I had gas under the bike. Turned the petcock and let the bike sit.

Next warm day was a week or two later. The bike fired right up. I went for a short ride, but the bike never seemed to warm up, and refused to idle regardless of choke lever position. I turned around and it felt like a low tire or something. Pulled into a gas station and discovered that I had oil coating the left side of the bike and all over the back wheel, basically from the center stand back. Still had oil in the sight glass, so I nursed it home and parked it. Total was under 5 miles. While it was running awfully, it wasn't making any unusual noises, never got a warning light.

I didn't check oil level immediately before I left, but it should have been fine--I'm a couple hundred miles after a clutch replacement, and while the bike does use a bit of oil it has never leaked before. I had just replaced the brake lines. I can't see where the oil is coming from with a visual inspection, haven't tried to run it since. The oil is all on the left side of the bike, coating the tire and driveshaft.

How do I find out where the oil is exiting from and how to fix it?

 

Many people have ridden XJ's with severely (gasoline) diluted oil without seizing the engine or reporting permanent damage.

The carbs are tipped forward, as they flood the gas goes down the intake and past the piston rings, slowly filling the crankcase. If there's a closed intake valve the gas backs up into the airbox and onto the floor.

When riding, the gasoline evaporates, boils in the motor, blowing out the PCV and into the airbox, wetting the filter, rendering it useless..I guess you could rinse the filter in fresh gas, then let it dry in the sun.

Oil and filter change are in order, Simple Green and some brushes and some scrubbing, hours later you can brag about having THE CLEANEST XJ on the planet!

(you also have a float needle/seat not doing it's job, so clean your carbs!)

 

I'm a little confused; so where's his oil coming from?

 

The crankcase.

All that gasoline got into his oil, overfilling and diluting it. Then riding it pushed it out the crankcase breather into the air box where it saturated his air filter. What the air filter doesn't soak up runs out the air box drain onto the top of the engine.

 

Exactly.

The ROOT CAUSE however, is a stuck or misadjusted float. Leaving it on "PRI" simply revealed the problem.

The carbs need to be serviced; float levels verified "wet" etc., or it will just happen again and again.

But change the oil and filter FIRST so the clutch isn't sitting in gasoline-diluted oil. And then quit riding the bike until the carbs have been serviced.

 

Ah! Thank you for explaining.

 

Most of this makes sense--I pulled the air filter this afternoon, and it is indeed coated in gasoline-smelling oil. There is a drain hole in the air box that is in a position to plausibly drain oil to coat the parts that are coated.

The only part that may not be completely consistant is the sight glass--it appeared that the remaining oil level was at the bottom of the glass. I will check again carefully tomorrow--it is possible that I'm misreading a smudge or something.

If I remember right, an oil change leaves some old oil behind in the trans, but draining the trans isn't normally recommended. Is that still the rcommendaton in this case, or should I do something else?

...and I'll talk to the mechanic who did the carbs, they were done this spring, I'd think they would last longer than that.

 

Maybe when he "did" the carbs he DIDN'T wet-set the float levels; it's a pretty precise adjustment. OR, you have a stuck float; not uncommon. Are you running an inline fuel filter? The one built into the top of the petcock won't stop much.

Being low on oil but having some left would very much be consistent with your symptoms.

You read the oil level when the bike is level or on the CENTERSTAND, and the motor off for at least 10 minutes. The proper level is at the top of the sight glass, above the marks, but with a bubble showing at the top.

The oil that you're referring to being "left behind" is about a 1/2 cup or so in the middle gear cavity. The transmission shares cases with the motor itself. Don't worry about that little bit in the middle gear case.

 

You'll want to drain the remaining oil, replace with good oil AND replace the oil filter. Get all the gas out. And yup, go through the carbs again.

Often bikes will have overheating symptoms due to that, surprised you didn't, unless you just didn't recognize it as such (feeling hot, bogging, sluggish, stalling, unable to start, sticky clutch, etc....).

Glad you didn't end up with the ultimate symptom of gas polluted oil in the crankcase........catching on fire.

Dave F

 

Uptate: Ordered and installed a new air filter, changed the oil and filter...and finally today was nice enough to ride. Took a little cranking to get going, but once it was warmed up the bike ran fine, just like it used to. Thanks everyone, before asking, I was shopping for donor bikes on Craigslist, convinced I'd destroyed my engine.

 

Riiigghht...

Except you never fixed the actual problem, just the symptom.

You had/have a sticking or misadjusted float, along with a (possible) petcock problem.

I'm thinking your petcock is fine but you have at least one float that isn't right, and slowly but surely it will keep adding gas to your oil until...

it happens again.

MONITOR your oil level closely, and SMELL it frequently. If it begins to mysteriously rise, or smell strongly of gasoline, you have a float issue. Ignore it at your peril.

Based on your previous experience, I would verify my float levels asap. Problems don' fix themselves; but they do hide, and bite you later.