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B s -- 31q777


Ralbon's Avatar
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04-07-12, 01:46 PM   #1  
B s -- 31q777

Husqvarna 42 cut, 18.5 BS single cyl, 05 model, 98 hrs, will not run unless choke is on and will not idle. Backfires and is using some oil. Smokes out of the fuel pump and muffler, any ideas on diagnosing this problem will be greatly appreciated. Thanks

 
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04-07-12, 06:01 PM   #2  
The problem with not running unless choke is on is because the carburetor needs cleaning.

The oil usage and smoke may be something else, but I would fix the carb first and see how it does.


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

God bless!

 
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04-07-12, 07:41 PM   #3  
Hello Ralbon,


I agree with Mr. Cheese on the carb cleaning, But also check the oil level in the engine. The carb could have flooded from a non seating float valve and filled the crankcase with fuel, This could cause the smoking from the muffler. If the oil is over full and smells of fuel, Clean the carb and replace the fuel filter then change the oil.


Good Luck

 
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04-12-12, 12:24 PM   #4  
B S 18.5 oil in carb

Cleaned carb, oil in carb, line from engine to intake has oil in it, spark plug is oil fouled, could breather valve be bad, is there supposed to be a valve or restrictor of somekind in the hose between intake and engine, oil level in engine is good and no fuel in the oil. Also checked gov and it is ok. Crankcase vent is under the flywheel, does flywheel need to be removed to change vent, what do i do next? Thanks

 
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04-12-12, 06:34 PM   #5  
Does the oil smell like gas? If not, then I would suspect you have a blown head gasket. The crankcase breather should be fine.


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04-13-12, 05:21 AM   #6  
Hi Cheese, why would a blown head gasket cause an oil problem, is the head gasket allowing oil into the cylinder? Why would this cause oil to be getting into intake? Thanks.

 
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04-13-12, 07:12 AM   #7  
You could also have a broken ring(s) on the piston which allows more combustion gasses into the crank case, pressurizing it which then vents back to the intake carrying oil mist & vapor. This will cause the engine to make smoke, use/burn oil and can fowl the spark plug. A hole in the piston is also a possibility but that's rather rare with a stock engine.

 
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04-13-12, 10:28 AM   #8  
The head gasket on these blows between the cylinder and the chamber that the push rods pass through. It's a common problem on this engine. When the gasket blows there, compression and combustion gasses get forced into the crankcase, pressurizing the crankcase. This pushes oil out the breather into the carburetor and also pushes oil past the rings into the cylinder, making a mess and a lot of smoke.

It could also be a broken ring as mentioned, but in over 20 years of working on these things, I may have only seen one or two broken rings, and that was because of foreign objects on the cylinder that hit the top of the piston, crushing the ring grooves.


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04-14-12, 05:16 AM   #9  
Hi Cheese, removed the head and the gasket is blown between the cyl and the push rod chamber. After seeing how this is designed I now understand the problem and how the blown head gasket can cause the problem with the oil. Thanks for all your help. God Bless.

 
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04-16-12, 12:51 PM   #10  
Hi guys: Replaced head gasket and the engine starts and will idle good, but rev the engine up and engage deck and the gov runs the engine up and down, rpm wise, what could be causing this, thanks

 
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04-16-12, 01:28 PM   #11  
It's usually a carburetor adjustement. Here is the Briggs & Stratton page describing how to adjust it.

 
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04-16-12, 07:26 PM   #12  
The carburetor needs a good cleaning. Engine surging is caused by a lean air:fuel mixture and high speed mixture is non-adjustable on these. It has a fixed main jet and is apparently partially clogged. They are set very lean from the factory to meet EPA requirements and sometimes the main jet needs to be reamed just a thousandth of an inch or less to stop the surging. That is only necessary in the rare occasion that it still surges after the carb has been completely cleaned.


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