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blowing white smoke out muffler


Boofhead's Avatar
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10-16-09, 10:02 AM   #1  
blowing white smoke out muffler

Hi all, yesterday whilst doing my lawns I stopped my 3 year old briggs & stratton 3.75 hp push lawn mower to empty the catcher, [ it was going fine before this ] then went to start it, the first pull of the cord was really hard [ unusual] and really jerked my arm, then the second pull it started normally but started to blow out a lot of white smoke out the muffler, the smoke was really bad, that bad i had to turn it off.

checked the oil level it was fine.
never tilted the mower at all.
used the same fresh petrol out of the container as what was put in the smoky mower, into another old mower to finish the lawns and it went fine.

any thoughts anyone,
thanks for any help in advance.

 
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10-16-09, 12:46 PM   #2  
Quote - the first pull of the cord was really hard [ unusual] and really jerked my arm, then the second pull it started normally but started to blow out a lot of white smoke out the muffler, the smoke was really bad, that bad i had to turn it off. - Quote


The pull rope trying to pull your arm off is a sign of the blade being lose or (and this is most likely the reason) a broken or shered flywheel key.Located under the flywheel keeyed to the cranksfaft.NEEDS REPLACING.

The real bad white smoke is a sign of water in the oil.Drain oil out and refill with fresh.

 
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10-16-09, 01:02 PM   #3  
Thanks very much for your reply, I will change the oil & check the flywheel key, if I turn the mower on its side and spin the blade assy the crank shaft will wobble if the key is bent, is this correct ?
thanks

 
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10-16-09, 01:25 PM   #4  
If you were mowing and there was no white smoke and the smoking started after you shut down to empty the grass catcher I don't think it's water in the oil. I'm wondering if you have a stuck ring letting oil get by.

 
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10-16-09, 02:09 PM   #5  
Ok, back again, the flywheel key is good & blades not loose, changed oil still the same deal, don't know why it jerked on the first start but easy to start now.
I guess its eliminating any possible causes now untill i find the culprit.

Thanks Pilot Dane, a stuck ring perhaps, any way of checking this without pulling the motor apart ?

I have been search the net for causes and come up with -
Inoperative crankcase breather
Crankcase air leak
Blown head gasket

Can anyone tell me were the crankcase breather is and how to test it.
Also how would you check a crankcase air leak ?

I would think a head gasket could be checked with a compression test [ i think]

thanks for any help

 
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10-16-09, 05:52 PM   #6  
Is there any way you can unstick a ring or do you have to pull the motor apart and replace it ?
really appreciate any help

 
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10-16-09, 07:09 PM   #7  
Before you start taking things apart, which may not be necessary, whenever you tilt the mower, to empty the bag, check the blade or whatever make sure the carb is always "UP". I think your smoke problems will go away. Have a good one. Geo

 
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10-16-09, 09:51 PM   #8  
Thanks Geo, and it did go away to, I left it for a few hours & restated it, it blow smoke for a while but not as bad as before then it slowly cleared up to back to normal.
I don't know what happened as I never tilted it to take the catcher off, however i just mowed in a decline which I have done many times before and nothing like this has ever happened before.
thanks for the help guys, time for a Beer 4U2

 
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