Fuel in oil

[bobiii84]

I think the title is self explanatory but I wanted to give some background information. I've recently been overhauling the electrical on my 1980 550L and was almost finished WHEN... I noticed it was blowing what almost looked like smoke, but not. I dismissed it due to cold weather and continued in my work. Tonight I was putting everything back together when I noticed my oil looked overfull. I thought it was odd so I pulled off the cap and sure enough, smells like gas. I've only heard of this happening one way, a bad fuel petcock. However, I'm pretty sure my petcock is fine, other than prime not really working like it should (It doesn't dump gas when set to prime, I still have to use vacuum) When I winterized the bike I forgot to tighten the carb drain screws all the way (First time, I know it was dumb) When I had my bike on the kickstand and started it a while back, it leaked gas out of the air housing. I figured the floats were stuck so I let it sit and figured they would come loose. When I started the bike this time, it was on the centerstand, so was tilted forward slightly. I think my floats are STILL stuck, at least one, and the gas seeped into the engine oil that way. Has anyone had this happen, or able to verify this? Also, can I use a stubby screwdriver and just pull the float bowls off while it's on the bike still to loosen whatever is stuck? I think I'm going crazy! Thanks in advance!

[Gumbo76]

Petcock

I've only heard of this happening one way, a bad fuel petcock. However, I'm pretty sure my petcock is fine, other than prime not really working like it should (It doesn't dump gas when set to prime, I still have to use vacuum)

I know you are pretty confident that your petcock is functioning fine, and that it's probably not the issue, but if the Prime is NOT working, then you have problems with it. I'd check to see if the plastic gasket. It may not be in there properly. There are three holes in it I believe which guide the gas through the Petcock depending on where you have the lever set. If you or the previous owner rebuilt it, it may not have been put back in correctly. It might be worth it to give it a check. And if you aren't sure what piece I'm referring to, check Part Number 3 on the Parts Fiche for the Petcock.

Also, the the best of my knowledge (and I wouldn't say I'm en expert by any means) in order for your float bowls being stuck and flooding the oil as much as you stated (noticeable difference in the oil level) , your fuel would still need to be overfilling the float bowls, thereby coming back to the Petcock.

Best of luck!

-Gumbo

[Nessism]

Common failure mode for the petcock is to dump fuel down the vacuum line and into the engine though the #2 carb. Running a clear hose on the vacuum line will tell the tale on this.

[mike_of_bbg]

Yep, check that vacuum hose for signs of fuel.

Usually one can rap on the bowls lightly with a wooden stick and get the needles to seat properly (provided the bowls are full).

[Dave8338]

"Fixed" more than one drunken float, that way.

A screw driver handle is my weapon of choice.

[GSexpress]

There are 3 things you need to check and or fix. first, if the floats and float valves are working properly even a leaky petcock won't cause your problem unless it is leaking into the vacuum line. This would cause just 1 cylinder to run bad and smoke or foul out. The one the vacuum line is connected to, Usually #3. If there's no sign of fuel in the vacuum line then a float or floats are stuck or it's valve/needle is leaking. This can let fuel leak into the carb and drain down into the oil. But it's limited to the fuel in the line if the petcock is working right. With the amount of fuel you seem to have in the oil it sounds like both the carbs and the petcock. Make sure to remove the excess fluid in the crankcase as it can blow out seals and gaskets if it gets too high. When you get it fixed you can add oil back in when the fuel evaporates out. Or just change it out once you know it's fixed. It is possible to remove the float bowls without removing the carbs but it's more work and difficulty than just pulling the carbs. You also won't be able to verify the float level adjust ment with the carbs in place. ( it is possible but can require multiple disassembly/assembly repetitions to check and fix things) You will find it easier to pull the floats and check the float needle valve condition and contamination with them out as well. The occational stuck float can sometimes be loosened by rapping on the float bowl. But not if it's been sitting for a long time and fuel has been able to solidify and glue the float in place. Plus you'll want to get that goo out of the bowl or it can cause more problems if it gets into the jets.

[bobiii84]

Well I hooked up a clear line for the air but it wasn't really the size I needed so I will have to grab a larger size. I emptied the fuel/oil and put new oil in. I then used wood/screwdriver to beat on the carbs a while. I ran it and kept an eye on the fuel level. It still got a little gross looking and put out some smokey exhaust but that may just be from what was still in there(IS still in there) It doesn't seem to be filling up with gasoline so hopefully it's taken care of. I would like to clear out the oil again, though, and add fresh so it stops the smoking altogether. I was thinking to be sure about the problem being fixed in the carbs I could do this. Drain out all the oil and leave the drain plug out. Put a bucket underneath for any excess drip. Unplug one of the spark plugs so it turns over but doesn't start up(That way I'm not running it and heat the engine up with no oil) Then I can watch to see if gas starts dripping out! Sound like a good idea?

I also sucked on the line for the petcock and never got any gas through that line, just fyi.

Am I also able to pull the plugs and see a visual difference to tell which carb I'm having trouble with? Thanks!

[bobiii84]

So I started it up the last couple days for a minute or two and I keep seeing the light smoke coming out the exhaust. I'm not sure yet if it's still leaking gas into the engine but if it is, it's less than it was. Anyone have any advice?

[BassCliff]

I was thinking to be sure about the problem being fixed in the carbs I could do this. Drain out all the oil and leave the drain plug out. Put a bucket underneath for any excess drip. Unplug one of the spark plugs so it turns over but doesn't start up(That way I'm not running it and heat the engine up with no oil) Then I can watch to see if gas starts dripping out! Sound like a good idea?

No, this doesn't sound like a good idea to me.

Am I also able to pull the plugs and see a visual difference to tell which carb I'm having trouble with? Thanks!

You can't really tell which carb is leaking this way. Unless you happen to pull the plug and the cylinder is full of gas. It will come spraying out when you spin the starter.

Have a look at these ---> Overflowing Carbs


Thank you for your indulgence,

BassCliff

[bobiii84]

So about this light smoke that's coming out. Is that still residual fuel burning off from what was in there before? It does smell a tad rich. I also noticed that the oil in the oil level window is normally clear, but after it runs for a few minutes, it's more of a bubbly unclear color. Is this normal? And I don't recall the exhaust ever blowing anything visible out before, so is the light smoky exhaust normal as well? Thanks!

[Mekanix]

No, this doesn't sound like a good idea to me.

Just to clarify, without some sort of lubrication, you run the risk of metal on metal contact in places like the crankshaft bearings, camshaft cylinder walls... It wouldn't be good.

Oil with gas in it isn't good to run either because it dilutes the oil and displaces the lubricating properties of the oil and you are likely to get metal on metal

For the smoking I have a few thoughts.

1 Condensation in the crank case, going through the breather hose into the airbox and through the carbs and eventually out the exhaust

2 gas/oil still in the exhaust pipes

3 gas/oil mix in the airbox.

but after it runs for a few minutes, it's more of a bubbly unclear color. Is this normal?

It's getting mixed up by all the moving parts in there.


good luck

[bobiii84]

Alright so I have been starting and running the bike for about 2 minutes everyday and shutting it back off because I want to see if the oil level is rising, which would indicate I still have fuel going in there. So far, it's better, but I'm not convinced that it's fixed. Is my best bet to just take off the carbs and clean them? Honestly, they are a pain to get off!