My Tractor Forum banner

1 - 20 of 37 Posts

·
Thank You MTF
Joined
·
124 Posts
Discussion Starter #1 (Edited)
Any ideas what could cause this? Still runs great - condition lasts 2-3 seconds and then it runs fine again. Smokes like crazy and smells like burned engine oil. (big cloud) I checked the oil and it is at the correct level, not sure what could be causing this.

Pic is from when I bought it in 2014.


IMG_2516.JPG
 

·
Registered
Joined
·
861 Posts
Mine did that...neighbors didn't seem to like it much. It was worn/sticking rings in my case. The problem was worse during cool months and during the first 15 minutes of operation. It became progressively worse over time. In my case, I was burning a 1/2 quart of oil per hour or so. I finally rebuilt the engine.

Does one or both of your plugs look fouled?
 

·
Thank You MTF
Joined
·
124 Posts
Discussion Starter #3
Mine did that...neighbors didn't seem to like it much. It was worn/sticking rings in my case. The problem was worse during cool months and during the first 15 minutes of operation. It became progressively worse over time. In my case, I was burning a 1/2 quart of oil per hour or so. I finally rebuilt the engine.

Does one or both of your plugs look fouled?

I haven't checked the plugs yet. I'll do that tonight and let you know what I find out.
 

·
Registered
Joined
·
444 Posts
My nearly new Cub with Kohler Courage engine started doing something similar. Oily mess, oil on the exhaust manifold, smoking, using oil, ruiined the rubber starter drive. I drove myself nuts trying to find out what it was - replacing valve cover gaskets, etc. I finally found a cracked low-oil- pressure sensor was pumping oil out under the flywheel fan and spraying oil everywhere. Something to check for along with other similar screwed in things.
 

·
Registered
Joined
·
972 Posts
Check the air cleaner. There is probably a line from the crankcase that is from the breather. My X534 spits up oil from that. I clean it out before every use, if I didn't it would definitely be blowing smoke. This can be caused by too much crankcase pressure (often caused by leaking rings). Since I see the same thing happen when the sparkplugs are out and I did a leakdown test, I am pretty sure that is not the cause on my engine. I am guessing that it is the breather valve not working correctly, so that is on the list to fix.
 

·
Thank You MTF
Joined
·
124 Posts
Discussion Starter #7
This just starting happening the last couple times I've mowed.

Seems to happen mostly at tight turns or slight uphill right hand turns.

Sent from my Pixel 3 XL using Tapatalk
 

·
Registered
Joined
·
5,475 Posts
Sounds like the oil is getting whipped up. Check the crankcase vent to the air intake for signs of oil. Are you sure it is not overfilled?
 

·
Registered
Joined
·
972 Posts
Here is a similar issue, but no solution:


Here's one that points to the breather valve and/or the dipstick. I swapped dip sticks with my X300 (it is shorter, but the otherwise fits) and the problem stayed with the X534. So, I think it is the breather valve. They also have an upgraded cover and removed the filter, so that might have something to do with it. It's a partial teardown to access it, so I haven't done it yet.


Here is one that says it was rings:
I am not sure I agree with the testing. I did a leakdown test on my X300 which runs fine normally (to make sure I knew how to do it and also to check its health). I forgot to remove oil dip stick before pressurized. It was fine for several seconds, and then it wasn't. Oil gushed out of the breather and made a huge mess. On my X534, I had both plugs out and heard weird gurgling sounds as I turned the crankshaft by hand. I looked at the output of the breather tube and there was oil there. So, the breather is supposed to remove excess air from the crankcase to prevent the crankcase from getting pressurized. The crankcase volume changes as the pistons go in and out. The breather valve is supposed to let air out (when the piston goes down into the crankcase, it reduces the volume, normally this would increase the pressure). When the piston goes back up, the breather valve is supposed to close and prevent any air from coming in. If it is working correctly, this will create a partial vacuum, since a smaller amount of air is filling a larger space. If the valve is letting air go both ways, this causes a lot of air to go in and out via the breather. That will overwhelm the chamber that is supposed to remove the oil from it.

Of course, if the engine is worn out, ie the rings are shot or the valve guides are leaking that can cause excess pressure to get into the crankcase and cause the same problem. In my case, I did a leakdown test which indicates a like new condition. I could hear air escaping the rings into the crankcase, but this is normal. If I hadn't seen the oil coming out with the sparkplugs out, I would have still been worried about the rings (I didn't hear anything from the valves). With the sparkplugs out there is no way that worn rings could be causing the issue, since there was no pressure in the cylinder. That pretty much leaves the breather valve. I am going to buy a new dipstick too, just to be safe. But, this is going to be a late fall project for me. I have no issue as long as I just clean out the air intake before every use. It would take many hours of use before there is enough oil to reach the carb.
 

·
Thank You MTF
Joined
·
124 Posts
Discussion Starter #10
Here is a similar issue, but no solution:


Here's one that points to the breather valve and/or the dipstick. I swapped dip sticks with my X300 (it is shorter, but the otherwise fits) and the problem stayed with the X534. So, I think it is the breather valve. They also have an upgraded cover and removed the filter, so that might have something to do with it. It's a partial teardown to access it, so I haven't done it yet.


Here is one that says it was rings:
I am not sure I agree with the testing. I did a leakdown test on my X300 which runs fine normally (to make sure I knew how to do it and also to check its health). I forgot to remove oil dip stick before pressurized. It was fine for several seconds, and then it wasn't. Oil gushed out of the breather and made a huge mess. On my X534, I had both plugs out and heard weird gurgling sounds as I turned the crankshaft by hand. I looked at the output of the breather tube and there was oil there. So, the breather is supposed to remove excess air from the crankcase to prevent the crankcase from getting pressurized. The crankcase volume changes as the pistons go in and out. The breather valve is supposed to let air out (when the piston goes down into the crankcase, it reduces the volume, normally this would increase the pressure). When the piston goes back up, the breather valve is supposed to close and prevent any air from coming in. If it is working correctly, this will create a partial vacuum, since a smaller amount of air is filling a larger space. If the valve is letting air go both ways, this causes a lot of air to go in and out via the breather. That will overwhelm the chamber that is supposed to remove the oil from it.
I do a compression test and check the plugs and breather.

Sent from my Pixel 3 XL using Tapatalk
 

·
Registered
Joined
·
861 Posts
There is not much to the breather system to go wrong. The reed valve prevents backflow into the crankcase acting as PCV valve. It does nothing to prevent oil from entering the carb.
 

·
Premium Member
Joined
·
2,177 Posts
I had an engine (used Tecumseh OHV snowblower engine) that had problems with smoking, and oil weeping from the engine while running.

I checked and measured a bunch of stuff. Sort of like Frogmore described, I eventually narrowed it down to a crankcase pressure & breather problem.

I checked for crankcase pressure/vacuum by building a simple water manometer. A length of clear plastic tubing, mounted to a rubber stopper that attached to (and sealed) the oil-fill tube. You run the tube down into a "U" shape, lower than the engine, and put some water in the tube. The water heights will equalize in the "U".

Then you crank the engine, and look for a crankcase vacuum (measuring the height difference in the water in the "U", if you want to calculate the vacuum), as the water pulls towards the engine in the "U".

If you have crankcase pressure, the water will be pushed away from the engine in the "U".

My tests showed crankcase pressure. And still showed crankcase pressure, even with the spark plug removed, which meant it wasn't related to compression, or something like worn rings, etc.

It's a simple test, the parts were maybe $5-10 at the hardware store, if you wanted to try something like that.
 

·
Registered
Joined
·
972 Posts
I actually bought a manometer (because I like tools and it wasn't that expensive). It showed good vacuum in the crankcase. So my guess is that the reed valve is sort of working. But, what I believe is happening is that the reed valve is letting air in. I can feel this by rotating the crankshaft with my finger over the breather hose end. I can feel suction and then pressure. The valve is supposed to prevent the suction. It appears to not be doing a good enough job on that. It does let out air like it is supposed to, so that means the pressure doesn't build up in the crankcase. But, because it lets air in too, more air is going in and out with each cycle. The breather oil separator is not designed to handle a large volume of air. Normally, it just has to vent the initial excess volume and any leakage. This is likely a lot less volume than what a leaky valve would allow. It also explains what I saw with my X300. Its rings don't leak a lot, but even a little (at 90psi) is more than the breather separator could handle continuously for more than 10-20 seconds. In normal use, the pistons are moving in and out, so the breather gets time to breath (pun fully intended) and isn't under pressure always. This allows the oil to drain back and not overwhelm the separator. Anyway, that's my story and I'm sticking to it (until proven otherwise). After talking about this so much, I am just going to order the parts and then tackle removing the flywheel. It is that part of the job that concerns me. I haven't done that before and I have heard some horror stories and also some good ones. Hopefully, my experience is, that was easy, why did I wait so long to try this?
 

·
Premium Member
Joined
·
2,177 Posts
I fixed the dumb problem that was present when I bought it used :) :) After buying it, I took pictures before disassembling it, and dutifully re-assembled it the same way.

Finally, after multiple rounds of head-scratching, measuring the cylinder bore, checking valves, etc etc etc, I did the manometer test, and narrowed down the problem to crankcase pressure.

But the breather valve had previously seemed to test OK. I swapped with one from another Tecumseh that I had, and it ran fine (but I just connected this one quick-and-dirty, not the exact same way as the original breather; this becomes important). Replaced the breather with a new one, still smoking. Very confused.

Until I took a closer look while re-assembling it. There was a rubber tube coming from the breather valve cover, to allow oil drips to drain, if needed. When I bought it, this tube was going to a port on the side of the carburetor. That seemed reasonable to me, I think some of them work that sort of way, so oil goes back into the intake, rather than onto the machine's frame.

Except I finally took a close look at the rubber tube, and the port on the carb. Turns out that carburetor port that the tube went to was kind of a "dummy" port, and was not drilled through to anything, it was just a dead-end. And therefore it plugged up the outlet from the breather, preventing it from actually venting the crankcase.

I explain this not to revel in my shame at how long it took me to find the problem, and to sigh at thinking about how much time I wasted disassembling the engine, and twisting off rusted fasteners :)

But instead to also make the point that things aren't always assembled correctly, and to double-check, or at least give it a sanity check, rather than just putting it back the way it was.
 

·
Registered
Joined
·
972 Posts
Hmm, there are different style breather valves for sure. It looks like the standard Tecumseh one is pretty easy to access. The tube is not for oil, but rather air. It is supposed to be connected to the intake (usually before the carb and after the air filter). This is the vent for the crankcase, putting it into the carb means the unburned hydrocarbons get a chance to become burned for lower air pollution. If the breather tube is blocked (like yours was) the crankcase will get pressurized, like you noticed/measured. On the Tecumseh, the metal box is supposed to help remove the oil from the air and drain that back into the crankcase.

Kawasaki has the breather integrated into the block, but it works the same way. And yes, it is always possible things are assembled incorrectly and can be really hard to find out exactly how things are supposed to be connected, even with the service manual. Sometimes they are quite vague on the details of what needs to be done, either because they assume everyone already knows how to do this, or (more likely) the writer of the manual doesn't really know the procedure and is getting the information from someone who knows it by heart but doesn't know how to explain it to someone who doesn't know (or thinks it is not necessary to explain something that is obvious, to them at least).
 

·
Registered
Joined
·
49 Posts
Tecumseh used a two part breather the cover and the box that contained the reed valve. Put the box on upside down and you will have a guaranteed leak. If you look closely at the box you will notice a very small hole in the one corner---that hole must be down and open to drain the oil out of the box. Wrong gasket or too much silicone can plug it and cause a leaker. Some manufactures have had issue with too small an oil return from the breather don't remember if Kawasaki is one of those or not.
 

·
Registered
Joined
·
972 Posts
I suspect that is what is going on with my X534. It probably still has the filter in the cavity. Newer models don't have that and have a thicker cover (to help prevent leaks). The service manual also says to "check for slugs blocking the drain hole", but I suspect they meant sludge. After I take it apart (and put it back together) I will have a better idea of what is causing the problem.
 

·
Registered
Joined
·
861 Posts
I suspect that is what is going on with my X534. It probably still has the filter in the cavity. Newer models don't have that and have a thicker cover (to help prevent leaks). The service manual also says to "check for slugs blocking the drain hole", but I suspect they meant sludge. After I take it apart (and put it back together) I will have a better idea of what is causing the problem.
As an FYI - the FD611V doesn't have a filter in the breather cavity. There are baffles that are cast in as part of the block but no filter.
 
1 - 20 of 37 Posts
Top