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Oil in Carb/exhast blowing out white smoke


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09-22-07, 01:59 PM   #1  
Oil in Carb/exhast blowing out white smoke

I have a Craftsman 16 hp riding lawnmower. This year I've noticed that I seem to be going through more oil than normal. Last week I was mowing and all at once it started to run rough and a whole lot of white smoke started to come outof the exhast. Kind of reminded me of how you see race car when it blows its engine. That's what I thought happen at first. Then it come out of it so I continued. A couple minutes late it did the same thing. I took the sparkplug out and was suprised at how bad it looked because I put a new one at the start of every season. It looked so bad I was suprised it even fired. When I went to get a new plug they told me to check my air filter because it could be dirty and cause it to burn rich. When I took the filter off there was oil in the carb. Everytime I put a load on the motor it blew oil out ofa rubber hose that went from the breather valve assembly to the air filter. After searching the forums here I come up with the breather valve assembly and the rubber seal at the bottom of my dipstick tube needed changed. I changed both them and it seemed like that did the trick. Or at least very little oil was coming out of the tube. I took it in the yard to try mowing and see what it did. It seemed like it wasn't running as fast and the blades just didn't sound like the where turning as fast as they should. Back in the garage I noticed this lever by the carb that if I pushed back on it it sped up. Maybe the govener? I don't know a lot about this stuff. Anyways I messed with that for awhile and at times the rpms was up there quite high. Never did get it where I wanted it because I started blowing oil out of the breather valve into the carb again. When I reved it up high like that did that make to much pressure in the motor and blow that oil out into the carb again? Or do I have something else wrong? I thought about taking the head off and seeing if the head gasket was ok. Would that give me problems with oil getting into the carb? The oil level is right where it needs to be and there is no gas getting into the oil. I have 10w40 oil in it right now but have 30w to put into it, just having changed it yet.

 
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09-22-07, 06:42 PM   #2  
The over-revving will definitely cause oil to blow into the carb through the breather. The 10-40 oil isn't helping either.

When you messed with the governor arm, did you loosen the nut and change it's setting?? If so, it needs to be reset. They are set for the engine at the factory, and should never need adjusting again. To reset, loosen the governor arm clamp, move the arm all the way to the right, rotate the governor shaft all the way clockwise, hold both in this position while you tighten the clamp nut. This is based on the assumption that you have a single cyliner briggs ohv 310000 series since you said sparkplug, not plugS.

Correct the engine speed and the oil, and see if it continues to smoke like that. If so, I would suspect a blown head gasket.


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09-22-07, 07:39 PM   #3  
I have to agree with Cheese. Use 30 weight oil in it & adjust your govenor to 3600 turns max. Also please verify you have no gas in the oil. It can sneak in there even after you checked it the first time!! Roger

 
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09-23-07, 07:44 AM   #4  
Ok--I checked the oil again and there is no gas in the oil. I drained the oil and changed it to 30w. I took the carb, the breather valve and and the sparkplug out (It only has one, It's a briggs ohv 310707 series) and cleaned the oil out of everything. Reset the governor. I had noticed the first time I had the carb off I must have bent the rod going to the governor so I straighten that. Put everything back together. When I started it everything looked and sounded good. Sound like the rpms where back the way it was before. Turned the blades on and they sounded like there where going the speed they were before also. Everything looked good but then within a minute of having the blades on it started spitting oil again so I shut it down before it got all into the carb again. So do I take the head off now and look at the head gasket? It looks pretty easy. Take off the exhast and carb then the 7 or 8 head bolts and it looks like it comes off. Never done it before. When I put it back on do I really need to use a torque wrench because I don't have one? Can I just tighten the bolts good. And when I have it off what am I really looking for? I'm new at all this stuff. Really am thankful for all the help here.

 
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09-23-07, 08:24 PM   #5  
You could pressurize the cylinder and check to see if the air is leaking into the combustion chamber faster than it should, but since it's pretty easy, I suggest just taking the head off and check the head gasket. I do reccomend using a torque wrench to ensure all bolts are torqued tight enough, but not too tight, and have equal pressure holding the head on. If you can't borrow one, try autozone or a big parts house. Many of them have rental tools.


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09-24-07, 08:17 AM   #6  
I have the head off. It looked like there was a dark spot between the piston cylinder and where the push rods go. If it was leaking over into where the push rods go would that be causing my problem? I have another problem now. After hunting around and finally finding a torque wrench in a town 20 miles away I got ready to put it together and I noticed the exhast and intake push rods are different. One is just a little bit longer. I thought they where the same so didn't pay attention which one went where. Now I would just be guessing which was which and didn't think that would be a good thing to do. Can anybody help me with this?

Thanks Dave

 
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09-24-07, 09:46 AM   #7  
I ended up having to order the head gasket. While I was there I asked them about the push rods and they told me the one with the red strip on it is the exhast push rod. They also told me that if I had any play in the valve stem guides that the head was worn and would have to be replaced. When I got home I took the springs of the valves and checked to see if I had any play. I had a little play in the exhast valve but not in the intake valve. I can see why play on the intake might make a difference but I can't see why play in the exhast valve would make a difference. The only time that valve would be open would be when the exhast was going out so it shouldn't be sucking any air in when the valve was closed, right? The seat on the exhast valve doesn't look to bad I didn't think.

 
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09-24-07, 06:54 PM   #8  
Don't worry about a "little" play in the exhaust valve guide. I work on a lot of golf carts & Yamaha doesen't even supply a valve seal for the exhaust valve. I think you're right in you're thinking. Roger

 
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09-25-07, 06:52 PM   #9  
I agree, I wouldn't get too worried over a little play in the exhaust guide. If it was running good (other than the smoking) before, then it should be fine. I've actually seen some with quite a bit of play that still ran good.

The area where you described the head gasket to be black looking is where the problem normally occurrs. The gasket leaks here, and compression/combustion gasses pass through this leak into the crankcase, creating excessive crankcase pressure...so much that breather fills with oil and begins to let it blow into the air filter housing.


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09-26-07, 01:00 PM   #10  
It's fixed!! Or at least I think it is. I put the head gasket on and at first it wouldn't fire. I checked and had spark so I took the valve cover off and cranked it. I noticed the intake valve wasn't moving. Tore it back apart and found I didn't have the intake push rod seated correctly. Put it all back together and it fired right up. Tested it a little while and no oil come out. Thanks for all the help. Couldn't or wouldn't have done it with out ya. Thanks again. I had to rent a torque wrench. Found one at Advance Auto Parts. I put a deposit down and can have the wrench for 45 days. When I return it I get all my deposit back. So it didn't cost a thing for the wrench. I thought that was pretty cool. So the whole thing cost me about $20. That was for the head gasket, oil dip stick seal and the breather valve assembly. I'm tickled pink. First time I've done anything like this.

 
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09-26-07, 04:32 PM   #11  
fun ain't it? glad it worked out....now you're hooked.

 
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09-26-07, 05:31 PM   #12  
Thats great. Thanks for letting us know how it turned out. Always good to hear a sucess story. Thanks, Roger

 
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09-26-07, 06:15 PM   #13  
Glad you got it! Thanks for the update!


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