Mysterious oil leak (big pictures) [Updated]

Message

DieMonkeys · Wed Jul 18, 2007 3:45 pm

If you look closely you'll see a couple of green lines showing you where the oil is dripping from.

This is the bike on centerstand with a piece of cardboard placed under it 20 minutes before. This is also a few hours after riding it home from work.

The bike seemed to run fine to and from work today (woo, Ride to Work day!) and I wouldn't have noticed it unless my dad said something.

I believe the kid I bought it from said last time he changed the oil he used some kind of car oil. I plan to do my own oil change as soon as I get the service manual (about two to three weeks from now) so I don't screw up, but I may as well change it out and guess how I go along.

Would car oil cause any negative affects when it gets hot, like mysterious leaks?

Oh yeah, 1986 Honda Nighthawk CB700SC

Here's the specs page: http://members.tripod.com/~stsamuel/spec.html

Sev · #2 Unread post by **Sev** » Thu Jul 19, 2007 2:44 am

It's leaking out of the muffler? That doesn't seem right. Looking a little higher it looks like there's some on the frame too... so it's probably coming from higher up and dripping down there. You need to find the source.

It is possible that you're having oil sneak past the rings and then get blown out through the exhaust, but that doesn't seem really likely to me because most of that would burn up when the engine is running.

Car oil shouldn't cause the bike to leak oil, it might ruin your clutch though, depending on what kind he used. Either way an oil change isn't going to solve your problem.

Clean the area really well and try to trace back the source of the leak.

BuzZz · #3 Unread post by **BuzZz** » Sun Jul 22, 2007 4:44 pm

I'll take 'leaking drain plug' for 50 cents, Alex.

DieMonkeys · Sun Jul 22, 2007 5:38 pm

BuzZz wrote:I'll take 'leaking drain plug' for 50 cents, Alex.

Nah, it's not that.

I did notice that the leaking oil had a bit of a gasoline smell to it.

Gasoline is getting into the oil, going past the rings and somehow going down the exhaust and leaking there. But there is hardly any smoke coming from the exhaust while running.

Changing the oil in the morning, mixing dye in with it (glows under blacklight) when I do so, as well as some seafoam. Then I'll go for a nice ride around the neighborhood, clean off the engine, then come back in 10 minutes, throw a blacklight on the bike and see where exactly the leaking comes from.

DieMonkeys · Mon Jul 23, 2007 7:41 am

Here are some pictures I took after mixing in the dye into the oil, going out for a short ride and throwing a blacklight on it in the garage.

The oil seems to be coming out from the exhaust, right where the muffler slips on. It then works it's way back and even gets all over the tire.

I'd be out riding the rest of the day but I'm worried about taking a right turn with oil on the tire and losing traction.

scan · #6 Unread post by **scan** » Mon Jul 23, 2007 9:47 am

This logically seems to make very little sense that it has to do with the muffler, unless you are losing a lot of oil. The exhaust system is hot, and too hot to hold a small amount of oil without smoking. It seems like you are losing oil somewhere above and/or in front of the muffler. When you added the dye, did you ride it, or just have it run sitting there? I'm just having a hard time seeing how you could be leaking so much oil from the engine, through the exhaust system, to be leaking from the muffler. I'd think there would have to be a quart of oil setting in the exhaust system to be dripping from it. If that is the case, this is one sick engine.

Car engine oil is a very small problem. It would maybe cause your clutch to slip if it was "energy conserving" car oil. Even at that, car oil does not cause engine leaks. I bad choice of oil at a change might make an engine more leaky than with the previous thickness of oil, but this also seem unlikely to be your problem.

If the bike just sat that and ran and leaked the dye like that, I'm pretty confused what could be leaking to cause that much oil on the right side. You said it was not smokey at all, right?

DieMonkeys · Mon Jul 23, 2007 2:34 pm

scan wrote:This logically seems to make very little sense that it has to do with the muffler, unless you are losing a lot of oil. The exhaust system is hot, and too hot to hold a small amount of oil without smoking. It seems like you are losing oil somewhere above and/or in front of the muffler. When you added the dye, did you ride it, or just have it run sitting there? I'm just having a hard time seeing how you could be leaking so much oil from the engine, through the exhaust system, to be leaking from the muffler. I'd think there would have to be a quart of oil setting in the exhaust system to be dripping from it. If that is the case, this is one sick engine.

Car engine oil is a very small problem. It would maybe cause your clutch to slip if it was "energy conserving" car oil. Even at that, car oil does not cause engine leaks. I bad choice of oil at a change might make an engine more leaky than with the previous thickness of oil, but this also seem unlikely to be your problem.

If the bike just sat that and ran and leaked the dye like that, I'm pretty confused what could be leaking to cause that much oil on the right side. You said it was not smokey at all, right?

I rode it, down to the Wawa to pump up the rear tire with a few more pounds of air. Never noticed a big cloud of smoke or any noticeable smoke from the exhaust. Same with running in the garage. I did notice when I got to the Wawa that there was alot of oil on the right side of the rear wheel. So I went straight home with as much caution as possible in right turns.

I put 20w-50 oil in there, non-energy conserving blah blah. I think it's just a leak, I'll keep a quart of oil with me at all times on the bike and top it off as it needs it. I don't really have high/low marks on my dipstick and no viewing window, so I kind of guess the oil line is going to be about midway of the hash marks.

I'm going to a get together a week from saturday to get some free advice from a mechanic a week from saturday. I'll have him look over the bike then.

Till then the only thing I worry about is the oil dripping onto the wheel when riding.

Mon Jul 23, 2007 4:01 pm

DieMonkeys wrote:....Till then the only thing I worry about is the oil dripping onto the wheel when riding.

If gasoline is mixing with the oil, then the oil is not protecting the engine and you have a lot more to worry about until the engine seizes.

DieMonkeys · Mon Jul 23, 2007 4:41 pm

DustyJacket wrote:
DieMonkeys wrote:....Till then the only thing I worry about is the oil dripping onto the wheel when riding.
If gasoline is mixing with the oil, then the oil is not protecting the engine and you have a lot more to worry about until the engine seizes.

Oh yeah, forgot to mention that I think that was just paranoia. I was sniffing and looking for an excuse for the leak. Also, had gas mix with oil on my last bike.

When I drained the oil this morning it wasn't as runny as I expected it to be, nor did it smell much like gasoline.

Also, the dye proved today that the brakes are fine.

I will, however, keep an eye on the oil to make sure no gas gets into it.

DieMonkeys · Sat Jul 28, 2007 3:22 pm

Well, I went around the neighborhood a bit tonight, came back and threw the blacklight on the right side. Revved the engine and oil was shooting out of a little hole in the bottom of the muffler. It's not a rust hole and the left side has it in the same spot. So the oil is leaking from there, when I ride the wind blows it up the muffler and onto all the surrounding pieces.

It drips while cold, it drips even more when hot.

I couldn't figure out how to get the muffler off, but to my guess there is a pool of oil coming down one of the headers into the exhaust.

So, oil flowing into the exhaust on the right side. What's the problem and what's the solution?

This is the right side of the bike: