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Oil coming out of exhaust?

99K views 58 replies 8 participants last post by  pjk 
#1 ·
Today oil started coming out of the exhaust and the bike just dies randomly when I'm driving. Oil doesn't seem to be leaking out of the engine itself, I only see it in the exhaust and the exhaust is an ugly burn. Any idea what is causing this? I've done nothing new to the bike lately. I suspect the o-ring broke. Does that sound right?

How difficult is it to replace this? Is it something I can do myself (I have very little knowledge about working with motorcycles)?. Thanks!
 
#3 ·
Bike make and model will help as if there's a common problem we may be able to tell you about it. Mileage too.

However, if it just started doing this out of the blue, then I would say you've probably got one of a few things happening.

1) Broken piston rings [which I assume is what you meant by o-ring] which are allowing oil to slip past them.

2) Cylinders are warped or worn out which again is allowing oil to slip past the piston rings.

3) Hole melted in the top of the piston. Usually caused by pre-ignition.

4) Broken/cracked head gasket.

Any one of these scenarios is going to require pulling the cylinder head off the bike.

How much/how fast is the oil coming of out of the exhaust?
 
#4 ·
Thanks for your replies and your time. Bike is a 2006 Zongshen GS250-5 Sportsbike, with 1700 miles. It just started out of the blue pretty much.

Oil isn't coming out too fast. The smoke is real ugly, and along the outer part of the exhaust pipe there is a thin layer of oil. How do I troubleshoot this? I can check the piston rings first, how difficult is this to do? Alternatively, approx. how much would it cost to take it in to get that fixed?

Thanks
 
#5 ·
1700 miles? Did you buy this new? If so, I would think the warranty would cover this work.

If you're not getting a lot of oil but a lot of smoke, I'm betting it's either piston rings or head gasket. One thing you can do to narrow down the cylinder, is to remove the spark plugs. An oil fouled spark plug will be black in color and appear to be wet.

However, all of the above scenario's I gave you are all things that can only be checked through removing the cylinder head. The only one that's really an exception would be the hole in the top of the piston- if you find an oil fouled plug, rotate the engine by hand until that piston is at the top of the cylinder, you may be able to shine a flashlight in the spark plug bore to see if the piston is ruined.

Does your bike have an owners manual? If so, many owners manuals, particularly for bikes, include maintenance information. Yours may also include info on how to set valve clearances and what not which would require turning the engine manually and so the manual should explain the proper procedure for doing so.

Are you getting any accompanying noises?

As to the cost of a shop fix, if this isn't covered under warranty [and at 1700 miles I really don't see why it wouldn't be], that totally depends on the shop. I would, however, tell you to be prepared to spend in the range of $1500, more or less, parts and labor. This type of work involves removing the cylinder head, which basically means the whole top end has to be taken off, the repairs made, and then reassembled. A shop will use new gaskets and parts along the way.

If you end up paying a shop for this work, take the time to do the research and find a good one. Good shops are hard to find though, so if it means taking the bike to a shop 30 miles away that has a good reputation, it would probably be worth it.

Keep us updated.
 
#7 ·
1700 miles? Did you buy this new? If so, I would think the warranty would cover this work.
Firstly, many thanks for taking the time with the detailed reply. I greatly appreciate it. I bought this bike off Craigslist. It had apparently been sitting in a shed for 6 months prior to me buying it.

If you're not getting a lot of oil but a lot of smoke, I'm betting it's either piston rings or head gasket. One thing you can do to narrow down the cylinder, is to remove the spark plugs. An oil fouled spark plug will be black in color and appear to be wet.
I read up more on this last night. It was on a car forum, but somewhat related. So when I got the bike, I drove it maybe 30 miles. One day when I was leaving a friends house (after riding around the block for a bit), I saw a few drops of black oil (I think it was oil) on the ground. I didn't think too much of it. When I got home, I checked the oil. It didn't seem like there was any oil. But then I checked it a few hours later after the oil was dripped out of the engine, the oil level looked good. The odd thing though was the oil was yellowish-clear, as if it was brand new. Reading up on this issue on the car forum they said that the engine coolant gets mixed into the oil when a head gasket breaks. That could be the case, but you'd think the oil would be a bit black. Any ideas?

However, all of the above scenario's I gave you are all things that can only be checked through removing the cylinder head. The only one that's really an exception would be the hole in the top of the piston- if you find an oil fouled plug, rotate the engine by hand until that piston is at the top of the cylinder, you may be able to shine a flashlight in the spark plug bore to see if the piston is ruined.

Does your bike have an owners manual? If so, many owners manuals, particularly for bikes, include maintenance information. Yours may also include info on how to set valve clearances and what not which would require turning the engine manually and so the manual should explain the proper procedure for doing so.
Here is my issue. I've been unable to locate a manual for this bike. I've been searching tons over the last 2 weeks with no luck at all. If I could get the manual, I'd be willing to buy the tools (as long as they aren't incredibly expensive), learn, and do it myself, especially if it would cost more than a couple hundred dollars. I have no experience with this, but with a manual and tools, I'm sure I could figure it out.

Are you getting any accompanying noises?

As to the cost of a shop fix, if this isn't covered under warranty [and at 1700 miles I really don't see why it wouldn't be], that totally depends on the shop. I would, however, tell you to be prepared to spend in the range of $1500, more or less, parts and labor. This type of work involves removing the cylinder head, which basically means the whole top end has to be taken off, the repairs made, and then reassembled. A shop will use new gaskets and parts along the way.
I haven't heard any noises. The bike sounds great and starts right up.


I think this is the guy who's been tryng to find a manual.
A very sad story; He probably got the bike at a tire store who didn't even tell him about the basics of break-in. When I worked at a shop, we had a constant barrage of people trying to get replacement chains- no clue. They're a weird size.

pjk, my heart goes out to you. It really does. Don't spend more than a couple hundred dollars on fixing this- the bike really isn't worth it. Maybe in China it's a different story...
They sell replacement parts on their site, and I've found tons on eBay. I could have had real bad luck, or it could be an issue that I could fix and the bike could work out fine. If I could get the manual, things would be much better. Right now I'm leaning toward taking it somewhere for a diagnostic, and then seeing where to go from there.

Thanks!
 
#6 ·
I think this is the guy who's been tryng to find a manual.
A very sad story; He probably got the bike at a tire store who didn't even tell him about the basics of break-in. When I worked at a shop, we had a constant barrage of people trying to get replacement chains- no clue. They're a weird size.

pjk, my heart goes out to you. It really does. Don't spend more than a couple hundred dollars on fixing this- the bike really isn't worth it. Maybe in China it's a different story...
 
#10 ·
Again, not knowing anything about Zongshens off the top of my head, I can't tell you exactly what tools you need. But there are basics-

1) A metric socket set, probably ranging from 8 - 20 mm. I think most standard sets will be from 10-18 mm, so you might just want to hit up a local Harbor Freight or Northern Tool for a cheap set if you don't have anything beyond a standard set. Harbor Freight has cheap tool sets which, for a motorcycle, should work just fine. Most sets come with a ratchet as well.

2) Straight and Phillips [cross] head screwdrivers, ranging in size from #1 - #3.

3) A set of metric allen wrenches - I bought a combination SAE and metric set ["Husky" brand] of allen wrenches from Home Depot a couple of years ago. I think it was about $20 for the set and they've turned out to be good quality.

4) A set of metric nut drivers only if you want to have them handy. I find that once I have the motor off my bike, it's much easier to use nut drivers than it is to keep changing sockets.

5) A torque ratchet. Again, can usually be found for cheap at a Harbor Freight or Northern Tool.

That's all I can think of for now. Typically speaking, any specialized tools are usually required for inside the motor so for the time being I wouldn't worry about it.

Again I want to emphasize that I'm not familiar with Zongshens, and for you to be snapping pictures and waiting on me to respond is going to take time. With any kind of mechanic work, patience is an absolute must.

I'm not really clear on what you're asking for the troubleshooting guide. Do mean a way to troubleshoot why oil is coming out of the exhaust; which as I've already told you the possible options for. Or are you wanting something to get you started in pulling things apart? That's why I was asking for pictures- to help you get started.

Also, one thing- are you positive you do not have a manual for this bike? Did the seller specifically tell you that there isn't one? I only ask because many bikes store the manual in a pocket under the seat, so it's possible it's just been overlooked up to this point.
 
#12 ·
I greatly appreciate your help, thanks once again. I've attached some pictures here (some are bad, but hopefully it helps some):
smg*.photobucket.com/albums/v113/pjkcards/Motorcycle/ (remove the *)

Also, I plan to start this next weekend, order any parts I need after, and finish it once they come in. I took off the seat and there was no manual, unfortunately. I plan to get one soon though.

try this number for Zongshin america; 305-500-9989. ssomeone there might be able to direct you to where you can get a service manual
Yep, I found that # today, I will call it on Monday. Thanks.
 
#13 ·
after re reading your symptoms they are similar to something i experienced with my hyosung GV250 a few years ago. on a long trip at prolonged high speeds we stopped and checked oil. didnt see any in sight glass (it was up to level before the trip because i did an oil change). we added a qt to bring it up to the bottom of the sight glass. the next morning the level was above the top of the sight glass. on start up it blew blue smoke and had oil coming out the exhaaust- not a lot but enough to notice. the bike ran great the rest of the trip from fla to nc. when i got home i changed the oil and after a few days the smoke stopped and no more oil from the exhaust. i did find oil in the air box as well. what we believe happened was that the oil level was fine but couldnt tell because the oil was dispursed throughout the engine. by addding the qt we over filled the crank case and it generated too much pressure on the seals forcing it into the airbox and combustion chamber (cylinders), too much to be all burned off which is why there was oil coming out the exhaust.
i dont know if this is the same problem you are experiencing but it is worth checking into by changing the oil and filter and runnning it for a few days to see if symptoms persist or performance drops.
 
#14 ·
Thanks for the idea. However, I didn't add any oil to mine, and when I check the oil, it is a yellowish color, which makes me think something is mixing into the tank. It started out of the blue too, without adding any oil. I would drain the oil and replace it, but I suspect that won't help. Oddly, this engine is air cooled apparently, so why would there be a yellowish color in the oil? The oil coming out of the exhaust is black...
 
#15 ·
oil coming out black is because it went through the cylinder, during combustion, mixed with exhaust carbon. new oil will have the color of honey. how do you check the oil level? As for all-of-a-sudden experience of the problem there are three areas where the oil will enter the combustion chamber; valves (bad seals, guides, valve seat), head gasket (blown or head requires retorque), or cylinders/pistons (bad rings, broke rings, damaged piston or damaged cylinder walls. start with the basics- change the oil and filter to remove tainted oil, do a compression check and compair your results to the specs in the manual, check your head torque. these are the least invasive things to do before tearing into things
 
#17 ·
oil coming out black is because it went through the cylinder, during combustion, mixed with exhaust carbon. new oil will have the color of honey. how do you check the oil level?
There is a little opening to check the oil level. I am yet to check it, but it was running fine for awhile before this issue happened. It is difficult holding the bike upright while looking at the level, so I will do that soon when I can get someone to help me.

As for all-of-a-sudden experience of the problem there are three areas where the oil will enter the combustion chamber; valves (bad seals, guides, valve seat), head gasket (blown or head requires retorque), or cylinders/pistons (bad rings, broke rings, damaged piston or damaged cylinder walls. start with the basics- change the oil and filter to remove tainted oil, do a compression check and compair your results to the specs in the manual, check your head torque. these are the least invasive things to do before tearing into things
I'm working on getting a manual, but am yet to get one. I can change the oil and filter easily. Compression test I'd have to look into more; from initial research it seems easy. How do I check the head torque? How simple is it?

i would also like to add that since your oil in the crankcase is yellowish i dont suspect a piston/cylinder wall issue. why? if they were bad then you would have blow-by where exhaust gases and carbon are forced past the rings or any damage in the walls or piston into the crankcase oil turning it black. i would lean more towards the valves or head gasket. bike dying is from, what i suspect, loss of compression. (oil leaked into the cylinder would create false compression upon startup until it is sufficiently burned off)
Excellent, good to hear. What would happen to the valves to cause this? In regards to the head gasket, how do these break? Too much compression?

I greatly appreciate your time and assistance, many thanks!
 
#16 ·
i would also like to add that since your oil in the crankcase is yellowish i dont suspect a piston/cylinder wall issue. why? if they were bad then you would have blow-by where exhaust gases and carbon are forced past the rings or any damage in the walls or piston into the crankcase oil turning it black. i would lean more towards the valves or head gasket. bike dying is from, what i suspect, loss of compression. (oil leaked into the cylinder would create false compression upon startup until it is sufficiently burned off)
 
#18 ·
ok, one more thing occurred to me. is the fas level lower than you remember. does the oil in the crankcase smell of gas? do you leave the petcock (fuel valve) on when parked? gas could be leaking past the carbs (bad float valve seat) into the carbs and into the cylinders. on newer bikes with good ring to wall seals the cylinders would fill with gas causing hydrolock. on an older bike the gas would flow past the worn rings into the crankcase, diluting the oil (piss yellow color) and raising your oil lever (higher pressures) these are just ideals that came to me. you must check to see if any are valid for your situation.
 
#19 ·
I will check this tomorrow and post back then. The gas may be a bit lower, but it is hard to say. I do leave the fuel valve on when parked. Is it suggested that it should be turned off? If this was the case, would there be gas on the ground after my bike is parked overnight? A couple days ago it was raining and I went out and I saw oil/gas near the bike, which I thought was a bit odd.
 
#20 ·
the manual will detail head torque proceedure and specs. head gaskets dont usueally blow due to pressure, rather from wear, usually induced by some point of access like an inprroperly torqued head. head torque may change over time due to repeated heating (thermal expanson/contraction ) of the engine. some might last forever and some might last onlly 10 years. can you refresh my memory; what year and model is your bike? doesnt it have a dipstick on the oil filler cap?
 
#22 ·
It is a 2006 Zongshen 250GS Sportsbike. Yes, there is a dipstick, but it is pretty worthless. From what I've researched, the oil level should be checked through the view window.

gas is much lower viscosity than oil so it would be possible that seepage from a crankcase seal might exsist if gas has actually entered the crankcase and if the carb is over filling then presumably gas would come out the overflow tube

And yes, it is always recommended that the fuel valve be turned to off when the bike is turned off, any manuall will state this
Good to know. Now can I just turn off the gas using the switch near the throttle or should I turn the actual gas off using the dial under the gas tank? Thanks!
 
#27 ·
Wow. Thanks playingotter- seriously.

I just caught up on all the posts you guys have, and every post of yours I read I keep saying to myself "Yep, didn't think of that." and it's all stuff that, in the back of my mind, I knew could be a problem.

Sometimes it's just too easy to overlook the basics and jump right to the complicated stuff.
 
#29 ·
I smelled the oil today. It seems to definitely have a smell of gasoline. As far as the level, it is quite difficult to check. The dipstick really has no markings on it, and the window is quite dark to see in, let alone you have to hold the bike upright while looking in it. With this said, should I change the oil and oil filter, and then try to get the level correct? Is that a good first step?

I've shut off the gas just now. It was sitting on for nearly a week.

Another thing that just crossed my mind:
I put some carb cleaner into the fuel tank a few days before this issue happened. Could that be at all related to this?
 
#30 ·
I doubt the carb cleaner had anything to do with it.

But if gas has been mixing with the oil, that would make sense why there's oil coming out of the exhaust as the gas would be thinning out the oil and making it easier for the oil to slip past the piston rings.

I would recommend an oil and filter change, then add seafoam to the tank and make sure it's mixed in well.

However, seeing as playingotter came along and really rocked his knowledge, might want to wait and see what he's got to say first. :D
 
#32 ·
That does make sense. I'd be happy if that is the problem so I don't have to take apart the engine. As for the seaform, do you want me to add it to the gas tank or oil tank or both?

Assume that this isn't the problem and the actual problem is a blown head gasket, how bad will it be on the bike if I try this and run it to see if the smoke goes away?

I agree with Gumby73 (cool name BTW). the oil change will remove the contaminated /diluted oil. keeping the petcock (fuel valve )closed when the engine is not running will prevent this from happening again, provided the diagnosis is correct. the smoke should disappear as well as the oil in the exhaust over a few days. remember though that the fuel over flow is the route cause and will need to be addressed at some point.
Over a few days.... approx. how many hours of running is that? With fresh oil and a clean filter in there, should the bike run fine if this is the issue? I don't want to push the bike if this isn't the correct diagnostic.

In regards to fixing the fuel overflow, does this involving opening the engine and replacing the rings on the piston? Or how difficult is it to fix it if it is a fuel overflow?

i also recommend that the head torque be checked. as Wombatunderground stated with the low mileage the enginge is just out of breakin and retorque is often required around that mileage.

is there a dot in the center of your site glass? usually a full oil level is read from the dot to the upper edge of the sight glass. Any thing above the top of the sight glass should be considered overfill since you cannot determine the level (otherwise the sightglass is useless).
Do you have any suggested guides for adjusting head torque (other than a service manual)? How difficult of a task is this?

I don't see a dot on the sight glass. I'll get this part figured out though.

Many thanks guys!
 
#31 ·
I agree with Gumby73 (cool name BTW). the oil change will remove the contaminated /diluted oil. keeping the petcock (fuel valve )closed when the engine is not running will prevent this from happening again, provided the diagnosis is correct. the smoke should disappear as well as the oil in the exhaust over a few days. remember though that the fuel over flow is the route cause and will need to be addressed at some point.

i also recommend that the head torque be checked. as Wombatunderground stated with the low mileage the enginge is just out of breakin and retorque is often required around that mileage.

is there a dot in the center of your site glass? usually a full oil level is read from the dot to the upper edge of the sight glass. Any thing above the top of the sight glass should be considered overfill since you cannot determine the level (otherwise the sightglass is useless).
 
#33 ·
this is the most simple solution. if it is not the cause then you move to the next level of complexity. As far as causing harm if it is not the solution. if it is an internal blown head gasket (one that leaks into the oil passages) it would pressurize your crank case and would cause oil to spray out the filler hole with the cap removed and the engine running in stead of splashing out. it might also cause the engine to stumble and stall. if it is an external blown gasket then it would vent to atmosphere and there would be tell tale carbon deposits around the head /cylinder mating area. there would most likely be noticable performance issues even at idle.

head torque proceedures would require removal of the tank, valve covers and possibly spark plugs and equipment to get clear access to the valves. the head bolts may be readily accessable at this point or beneath a cam, no way to tell unless you have a manual. manuals will not only give you torque specs but also order of which bolts are torqued and if in steps. bolts are not tightened in a random pattern. pattern is specific to keep head from warping.
 
#34 ·
if it is a fuel overflow condition then the cause is in the base of the carburators, the engine would not have to be opened. the valves that are activated by the float may be blocked by debris not allowing it to shut completely when the fuel level raises the float. think of the float valve in a toilet tank. when the water level rises the water filling the tank shuts off.
if continues to drip water then the valve isnt shutting off.
in a carb the fuel fills bowl and as it rises to a specific level it raises the float shutting off the fuel flow. as the bike runs and uses tthe gas the level in the bowl drops and lowers the float, opening the float valve allowing more gas to enter the bowl
 
#36 ·
Great, thanks for the info.

My next step is to buy an oil filter. Unfortunately, without a manual, I will have to do some searching. Are oil filters for motorcycle available at most auto part stores, or do I need to order it specially online?
 
#39 ·
i read that earlier. might explain why you cant find replacement info on them. have you ever done an oil change? if not, filters usually go in a specific way. if it is reversed it will not filter and may actually restrict circulation of oil and engine cooling. be sure to note the direction of the filter as well as location of any springs or o-rings.
 
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