fuel in oil
Thread Starter
|
Advanced
Joined: Oct 2006
Posts: 68
Likes: 0
From:
fuel in oil
What would cause fuel in the oil? I was reading some other threads that said it can be a result of starting without riding or not letting the bike reach a high enough temp. My oil seems to be fouled with gas and was wondering what else might casue this.
Advanced
Joined: Nov 2006
Posts: 52
Likes: 0
RE: fuel in oil
Doak,
what year bike do you have? Do you have a gravity or vacuum fed petcock? If you have a gravity fed petcock then you need to ensure you turn the petcock to the off position EVERY time you stop the bike (even if only for a short time). With the gravity fed petcocks you can get a bit of grit in the sealing seat. This causes the feed needle to remain off the seat and you then get a constant drip into your combustion chamber which washes down your cylinder walls (not good). This fuel then mixes with the oil left over in your crankcase and is then recycled with the other oil in the tank. In fact, I have a vacuum operated petcock but I still make it a habit of turning off the petcock - you just never know. Does this sound like it could be your problem?
Cheers.
what year bike do you have? Do you have a gravity or vacuum fed petcock? If you have a gravity fed petcock then you need to ensure you turn the petcock to the off position EVERY time you stop the bike (even if only for a short time). With the gravity fed petcocks you can get a bit of grit in the sealing seat. This causes the feed needle to remain off the seat and you then get a constant drip into your combustion chamber which washes down your cylinder walls (not good). This fuel then mixes with the oil left over in your crankcase and is then recycled with the other oil in the tank. In fact, I have a vacuum operated petcock but I still make it a habit of turning off the petcock - you just never know. Does this sound like it could be your problem?
Cheers.
Seasoned HDF Member
Joined: Dec 2006
Posts: 8,232
Likes: 6,168
From: Black Hills
RE: fuel in oil
This is a serious problem that can do tremendous damage to your engine if it ignites. I had a Honda that did the same thing if I didn't turn off the petcock.
I had a buddy that owned a repair garage. A customer had his van towed in because it wouldn't start. The customerdidn't tell him he pumped the pi$$ out of it trying to start it and filled the oil pan with gas. Mike went out and tried it later in the day and when itstarted the oil pan was blown completely off the bottom of the engine when the gas ignited. It was something that you would not believe unless you saw it.
I had a buddy that owned a repair garage. A customer had his van towed in because it wouldn't start. The customerdidn't tell him he pumped the pi$$ out of it trying to start it and filled the oil pan with gas. Mike went out and tried it later in the day and when itstarted the oil pan was blown completely off the bottom of the engine when the gas ignited. It was something that you would not believe unless you saw it.
Banned
Joined: Mar 2007
Posts: 3,706
Likes: 7
From: Woodstock, Ont , Can
RE: fuel in oil
Ignition of the crankcase is truly a rare event. You would almost need a hole in the piston to supply flame to it. As an example the old Harvard or T6 asthey are called in the states use to pump gas into the oil to thin it for cold weather starting. This was the early version of multigrade. After flying around for a while the gas evapourated out of the oil and the viscosity came back. If you ever saw one of these things start up, there would be every reason for it to blow up with gas mixed in the oil. Never happend to my knowledge. During the shutdown more gas was added to the oil prior to the next cold winter morning start. History lesson over.
Ron
Ron
Trending Topics
Cruiser
Joined: Nov 2007
Posts: 156
Likes: 2
From: Here and there.
RE: fuel in oil
A few things to check:
1)Petcock as stated. Take the fuel line off and turn fuel valve off and see if the petcock leaks at all. Use a small container under it to catch the gas.
To determine if it's vacuum or not, just look towards the back and look for the vacuum line going to it. If it has one, the valve only opens when vacuum is applied to the diaphram, despite if the lever is pointed to the "on" position. If the diaphram goes bad: No gas.
2.) Leaking carb. It can be due to dirt in the bowl, low float level, bad float, ot a worn viton tip on the needle. They occasionally go bad as well.
I've never seen an oil pan blow off an engine, due to fuel content in the oil. Sounds like one of those urban myths....
1)Petcock as stated. Take the fuel line off and turn fuel valve off and see if the petcock leaks at all. Use a small container under it to catch the gas.
To determine if it's vacuum or not, just look towards the back and look for the vacuum line going to it. If it has one, the valve only opens when vacuum is applied to the diaphram, despite if the lever is pointed to the "on" position. If the diaphram goes bad: No gas.
2.) Leaking carb. It can be due to dirt in the bowl, low float level, bad float, ot a worn viton tip on the needle. They occasionally go bad as well.
I've never seen an oil pan blow off an engine, due to fuel content in the oil. Sounds like one of those urban myths....
HD Forum Stories
The Best of Harley-Davidson for Lifelong Riders
7 Surprising Harley-Davidson Products that Are Not Motorcycles
Verdad Gallardo
8 Best Harley-Davidson Motorcycles Ever
Pouria Savadkouei
10 Worst Harley-Davidson Motorcycles Ever
Pouria Savadkouei
Killer Custom's Jail Break Is The Breakout That Refused to Blend In
Verdad Gallardo
Crazy Bunderbike Build Looks Amazing, But Is It Impossible to Ride?
Verdad Gallardo
Harley-Davidson Reveals Super Cool Cafe Racer Concept
Verdad Gallardo
Engraved Rebellion: Inside Bundnerbike's Glam Rock II
Verdad Gallardo
10 Motorcycles You Should Never Buy
Joe Kucinski
10 Things Harley-Davidson Needs to Fix in 2026
Verdad Gallardo
Cruiser
Joined: Dec 2007
Posts: 213
Likes: 2
RE: fuel in oil
Go put your carburated car on its side like your bike and see if the carb doesn't leak due to the float leaning. You need to shut off the gas when you shut off the motor. Make it a habit.
Every HD I have owned Pan, Shovel and my Evo did and do leak if the petcock is not closed. In fact I can remember Jap models leaking also.
