Can a stuck float actually allow gas to run into cylinder and seep past poison rings into crank case?
Yes
Randy - RPM
That's what I thought. That probably not a good thing at all for the cylinder or bearings.
Quote from: twangin4u on April 09, 2016, 02:41:06 PM
That's what I thought. That probably not a good thing at all for the cylinder or bearings.
Possible hydro lock and major engine damage??? Check your oil for fuel...
Quote from: twangin4u on April 09, 2016, 02:04:19 PM
Can a stuck float actually allow gas to run into cylinder and seep past poison rings into crank case?
Do you still have the air box? Fuel can also back flow into the air box and drain down thru the crankcase breather tube and directly onto the case.
Ya I noticed fuel dripping out from between the carb and the airbox. My oil level is much higher now too. Luckily I haven't ran it since it's leaked. I'll just drain the oil and replace when I get the carbs straightened out
Consider buying a new petcock.
With your engine off, no vacuum, that petcock should not let any gas thru to your carbs.
Mine actually over flowed the crank case. Then switched to manual petcock.
Yes , the petcock is probably leaking . Caused bent rods for the PO of my FJ.
I spent most of the day fighting a bad or stuck float...had carbs on and off three times. Thank God for pods! After rechecking float heights, replacing needle/seat O-rings, I started it up without and noticed fuel in puddleing in the bottom of of #4 carb below the slide....and of course leaking out the overflow. Went to my parts set and took a float out and replaced the float in #4. Leak stopped. I cannot see any damage to the one I removed. Do they sometimes get "gas-logged"? New one on me.
All things can and will eventually fail. The ones destine to fail after we are done with them (past our life time) never get noticed. Good catch.
Quote from: jscgdunn on April 15, 2016, 06:44:03 PM
...... I cannot see any damage to the one I removed. Do they sometimes get "gas-logged"? New one on me.
Hey Jeff, did you do the water test?
Put the float in a bowl of water. Weight the float so it stays submerged at the bottom.
Let it sit for a couple of days. Take it out and shake it. Do you hear or feel any water sloshing inside?
Then you have a leaky float.
Sometimes the surface of the tab on the float can be worn from the float needle. Noel has a good picture of this. Polish out the burr on the float tab.
Cheers
Quote from: Pat Conlon on April 15, 2016, 07:18:07 PM
Quote from: jscgdunn on April 15, 2016, 06:44:03 PM
...... I cannot see any damage to the one I removed. Do they sometimes get "gas-logged"? New one on me.
Hey Jeff, did you do the water test?
Put the float in a bowl of water. Weight the float so it stays submerged at the bottom.
Let it sit for a couple of days. Take it out and shake it. Do you hear or feel any water sloshing inside?
Then you have a leaky float.
Cheers
Pat, that's a good tip but it needs to be submerged in fuel, or some other "thin" spirit, not water. Fuel will pass through openings that water won't.
Perforated brass floats are spoken about far more than they are experienced but I have seen plastic ones split at the seam.
Noel
Ok, very good point Noel, thank you. Do you have that picture to show us of your fix on the float tab?
We really need to put that in the Files.
Quote from: Pat Conlon on April 15, 2016, 08:35:05 PM
Do you have that picture to show us of your fix on the float tab?
We really need to put that in the Files.
(https://c1.staticflickr.com/9/8589/15789683033_964fd2d192_c.jpg)
Noel
Quote from: twangin4u on April 09, 2016, 06:57:08 PM
Ya I noticed fuel dripping out from between the carb and the airbox. My oil level is much higher now too. Luckily I haven't ran it since it's leaked. I'll just drain the oil and replace when I get the carbs straightened out
Hey, one advice. After you changed your oil and fixed the leaking petcock/carbs still DO NOT CRANK THE ENGINE! First remove all the spark plugs and crank it with them removed to spill out the fuel if the cyllinder was/is overflowed. If you don't do this and your cyllinder is full, you will hydrolock it and end up with bent connecting rods at best.
Ivan
Quote from: balky1 on April 16, 2016, 02:13:39 AM
Quote from: twangin4u on April 09, 2016, 06:57:08 PM
Ya I noticed fuel dripping out from between the carb and the airbox. My oil level is much higher now too. Luckily I haven't ran it since it's leaked. I'll just drain the oil and replace when I get the carbs straightened out
Hey, one advice. After you changed your oil and fixed the leaking petcock/carbs still DO NOT CRANK THE ENGINE! First remove all the spark plugs and crank it with them removed to spill out the fuel if the cyllinder was/is overflowed. If you don't do this and your cyllinder is full, you will hydrolock it and end up with bent connecting rods at best.
Ivan
Safe advice Ivan but it's probably faster just to turn the engine over by hand to make sure it's free.
The fuel won't sit in the cylinders for long anyway, being thin, it runs past the rings, that's how the crankcase fills up.
There's also a good chance it runs past the rings faster than it leaks in, the flow rate from the offending carby not being very high.
I've actually only ever seen one example of hydraulic locking of a cylinder causing damage. An H2 Kawasaki (2 stroke) lying on its side for half an hour following an accident then immediately trying to bump start it down a hill as soon as it was stood upright - bent crankshaft.
The rider was not only stupid enough to crash it but stupid enough not to have considered that possibility - and he should have known better!
Noel
Quote from: ribbert on April 16, 2016, 02:56:58 AM
Quote from: balky1 on April 16, 2016, 02:13:39 AM
Quote from: twangin4u on April 09, 2016, 06:57:08 PM
Ya I noticed fuel dripping out from between the carb and the airbox. My oil level is much higher now too. Luckily I haven't ran it since it's leaked. I'll just drain the oil and replace when I get the carbs straightened out
Hey, one advice. After you changed your oil and fixed the leaking petcock/carbs still DO NOT CRANK THE ENGINE! First remove all the spark plugs and crank it with them removed to spill out the fuel if the cyllinder was/is overflowed. If you don't do this and your cyllinder is full, you will hydrolock it and end up with bent connecting rods at best.
Ivan
Safe advice Ivan but it's probably faster just to turn the engine over by hand to make sure it's free.
The fuel won't sit in the cylinders for long anyway, being thin, it runs past the rings, that's how the crankcase fills up.
There's also a good chance it runs past the rings faster than it leaks in, the flow rate from the offending carby not being very high.
I've actually only ever seen one example of hydraulic locking of a cylinder causing damage. An H2 Kawasaki (2 stroke) lying on its side for half an hour following an accident then immediately trying to bump start it down a hill as soon as it was stood upright - bent crankshaft.
The rider was not only stupid enough to crash it but stupid enough not to have considered that possibility - and he should have known better!
Noel
Yes, turning it by hand is also a possibility. But since I was too lazy for that I did it my way. Also it would be much easier to turn it by hand with spark plugs removed. :-D
Oh, and it happens a lot more than you think that a cyllinder gets full of gasoline (not even needed for it to be full, it is enough that the volume of gasoline inside it gets higher than the rest of the volume you get in the cyllinder on the compression stroke since the liquid is incompressible, if you get me). I've seen it happen often when such overflowing happens. For a precaution, I would deffinitely do it. Two minutes to remove the plugs can save a lot of money. :good2:
Quote from: ribbert on April 15, 2016, 08:59:24 PM
Quote from: Pat Conlon on April 15, 2016, 08:35:05 PM
Do you have that picture to show us of your fix on the float tab?
We really need to put that in the Files.
(https://c1.staticflickr.com/9/8589/15789683033_964fd2d192_c.jpg)
Noel
Pat,
You nailed it in my case. My float has exactly the same divot as in the pic. Strange how it did not leak one day but started the next!
Jeff
Thanks Jeff, but the credit goes to Noel. :good2:
Quote from: Pat Conlon on April 09, 2016, 09:52:15 PM
Consider buying a new petcock.
With your engine off, no vacuum, that petcock should not let any gas thru to your carbs.
Forgot I needed to update my picture. Lol. I traded my '84 for a '91. No vacuum petcock on this one. It did have a manual petcock valve on it.. Until mice decided to sharpen their teeth with it. Now it's a nub.
Thanks to new needles and seats it hasn't leaked a drop since. Pretty happy about that. Ever just dumped 4 gals of gas on the floor of your garage? Sucks. Especially when it's the first thing you see/smell when you wake up in the morning. Lol
Quote from: twangin4u on April 18, 2016, 11:31:02 PM
Quote from: Pat Conlon on April 09, 2016, 09:52:15 PM
Consider buying a new petcock.
With your engine off, no vacuum, that petcock should not let any gas thru to your carbs.
Forgot I needed to update my picture. Lol. I traded my '84 for a '91. No vacuum petcock on this one. It did have a manual petcock valve on it.. Until mice decided to sharpen their teeth with it. Now it's a nub.
Thanks to new needles and seats it hasn't leaked a drop since. Pretty happy about that. Ever just dumped 4 gals of gas on the floor of your garage? Sucks. Especially when it's the first thing you see/smell when you wake up in the morning. Lol
I know the feeling. I had some celebration with my friends, allready a bit drunk, and then smelled the gas throught the window. Imagine that tank removal. :rofl:
A better way to get fuel to dump out of the cylinder is to pull the plug, put it in gear, and use the rear wheel to turn the motor over backwards.
Any fuel left in the combustion chamber will get pushed out the exhaust valve rather than compressed.
Of course, this technique assumes that the cylinder filled up because the intake valve was open.
Will fuel leak past a closed intake valve?
Quote from: FJ_Hooligan on April 19, 2016, 10:04:44 PM
A better way to get fuel to dump out of the cylinder is to pull the plug, put it in gear, and use the rear wheel to turn the motor over backwards.
Any fuel left in the combustion chamber will get pushed out the exhaust valve rather than compressed.
Of course, this technique assumes that the cylinder filled up because the intake valve was open.
Will fuel leak past a closed intake valve?
Fuel will most likely leak past the cylinder rings and into the oil sump. Take the plugs out to be safe, it may be less expensive.
Quote from: balky1 on April 16, 2016, 02:13:39 AM
Quote from: twangin4u on April 09, 2016, 06:57:08 PM
Ya I noticed fuel dripping out from between the carb and the airbox. My oil level is much higher now too. Luckily I haven't ran it since it's leaked. I'll just drain the oil and replace when I get the carbs straightened out
Hey, one advice. After you changed your oil and fixed the leaking petcock/carbs still DO NOT CRANK THE ENGINE! First remove all the spark plugs and crank it with them removed to spill out the fuel if the cyllinder was/is overflowed. If you don't do this and your cyllinder is full, you will hydrolock it and end up with bent connecting rods at best.
Ivan
Ya that was actually the first thing I did. I took plugs out and carbs off and blew though both sides with compressor. Id say about two cups of gas cans gushing out the intake. Good call. Thanks. All is well now. She purrs like a kitten
That's always the best prize you can get. :yahoo:
Quote from: FJ_Hooligan on April 19, 2016, 10:04:44 PM
A better way to get fuel to dump out of the cylinder is to pull the plug, put it in gear, and use the rear wheel to turn the motor over backwards.
Any fuel left in the combustion chamber will get pushed out the exhaust valve rather than compressed.
Of course, this technique assumes that the cylinder filled up because the intake valve was open.
Will fuel leak past a closed intake valve?
Hooli, I believe the manual says, and it's a golden rule of chain/belt drive OHC engines not to rotate the engine backwards.
Re your question "Will fuel leak past a closed intake valve?"
I suspect you already
know the answer to this, no, it won't if your seats are in good nick.
I have been using this method of checking valve seats (intake and exhaust) for nearly 50 years. With valve closed, fill the port with petrol and leave. If fuel shows up, valves seats are crook.
A well seated valve will not let petrol pass.
Noel