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Tecumseh motor blowing oil into carb


Gravely's Avatar
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07-15-06, 01:50 PM   #1  
Tecumseh motor blowing oil into carb

I have a Toro 6.5hp mower which is 2 years old. It has been running fairly lousy this season and today I took the carb off and cleaned out all of the passages and jets. I noticed that the air filter is soaked in oil and the motor has been smoking worse each time I use it. I found a hose that goes from the crankcase (under the flywheel ) to a fitting on the carb. This hose is apparently a breather hose and when the engine is running, this hose is spraying motor oil out if it. I assume that there is a PCV valve of some sort somewhere and it has failed. This is turn is causing the oil to be ejected from the crankcase via this hose.

Is my analysis of the problem correct? If so, what part do I need to replace and where is that part on the engine?

Thanks,

 
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07-16-06, 06:36 PM   #2  
Does the oil smell like gas?? if it does, the carb needs fixed. Make sure the crankcase is not over full. Also make sure you're using SAE30 motor oil. Post the engine numbers & i'm sure Cheese or someone can give you an answer.

 
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07-17-06, 04:52 AM   #3  
I do not have the engine part number in front of me but I will look it up tonight. This motor is only a few years old ( 3?). I have thought more about this and I would guess that something is causing the crankcase to be pressurized. Why else would oil be spraying out of the vent hose? I removed the hose from the carb and let it spray into a bottle. the mower runs fine then but the bottle quickly fills with oil. Is this maybe being caused by too much blowby? I guess a broken ring could cause this condition but is this a common problem with these newer Tecumseh engines?

The motor oil level is actually low and the correct oil is in the engine.

Thanks.

 
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07-17-06, 10:06 PM   #4  
Gravely,

Your breater or (PCV) valve is gone. Follow the hose from the carb breather to the crank case breather. There are two screws that holds it into the valve case. Remove and replace it along witht the gasket(s).

If you rings were damaged enough for blowby it would be smoking badly.

God Bless,
Dave237

 
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07-17-06, 11:50 PM   #5  
I'm sure with the amount of oil you're describing, this one's smoking pretty bad right now. The breather could be at fault, but not likely. On this engine, (not sure exactly what model) the breather shouldn't be held on with screws, but rather pushed into the crankcase under the flywheel. Sounds to me like you have blowby. Before replacing the breather, I'd pull the head and have a look at the cylinder. I'd bet it's scored, or the head gasket is blown if this is an OHV engine.

Did you actually smell the oil to be sure it doesn't smell like gas?


"Who is John Galt?" - Ayn Rand (Atlas Shrugged)

God bless!

 
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07-18-06, 04:44 AM   #6  
cheese, I pulled the carb and cleaned out all of the passages and jets with carb cleaner and compressed air. After reassembling everything, the motor started on the first pull but it was still running badly. I verified that the needle valve/float assembly is sealing properly and that the float level is correct. After that, as I started looking closer at things, I noticed that oil was blowing into the carb intake. I removed the breather hose from the carb and started the mower. The mower ran fine then but oil was blowing out of that breather at a high-rate. I tried removing the dipstick while the engine was running and I had an oil geyser going in my driveway. It sure seems to me like this mower has so much blowby that the crankcase is being pressurized. By the way, the PCV valve is as you describe where it is a rubber fitting pressed into the top of the crankcase under the flywheel. The 2-screw design must be an older model.

The mower is smoking badly but because of the all the oil in the system and muffler, I cannot tell if it truely smokes when the breather line is disconnected. With that line disconnected, I also have the added bonus of about 1/2 qt of oil per minute being blown out of the breather.

- ron

 
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07-18-06, 05:58 AM   #7  
I've not seen a engine blow that much oil in such a short period of time but I'd think that you have a leak in the crankcase. Now you will have to determine where exactly it is. Being only three years old and assuming you have low hours on the engine, I doubt that the rings are to blame. Other areas to look are: Magneto-end crank seal, PTO-end crank seal, the oil fill tube seals (top and bottom, with the bottom the most likely), the breather assembly itself, the sump gasket and finally, the valve guides. Don't get me wrong, it could have a toasted ring or rings on the piston, it's just not very likely.

 
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07-21-06, 02:28 AM   #8  
Posted By: Gravely I have a Toro 6.5hp mower which is 2 years old. It has been running fairly lousy this season and today I took the carb off and cleaned out all of the passages and jets. I noticed that the air filter is soaked in oil and the motor has been smoking worse each time I use it. I found a hose that goes from the crankcase (under the flywheel ) to a fitting on the carb. This hose is apparently a breather hose and when the engine is running, this hose is spraying motor oil out if it. I assume that there is a PCV valve of some sort somewhere and it has failed. This is turn is causing the oil to be ejected from the crankcase via this hose.

Is my analysis of the problem correct? If so, what part do I need to replace and where is that part on the engine?

Thanks,
THIS IN MY 30 YEARS EXPERIANCE IS VERY LIKELY THE BREATHER ASSEMBLY. IF IT RAN FINE WITH BREATHER HOSE DISCONNECTED IF RINGS WERE BAD ENOUGH TO BLOW BY TO THAT EXTENT IT WOULD BE VERY UNLIKE TO EVER START ON FIRST PULL,AND WHEN IF AND WHEN IT DID START IT WOULD NOT ANY KIND OF POWER.....

 
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