Briggs Engine Problem


Old 05-01-06, 09:44 PM
Old man
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Briggs Engine Problem

Hi All,
I am trying to help my neighbor lady, elderly widow.
She has a Craftsman rider with a 15.5 hp engine. It recently started blowing blue smoke out the exhaust when blades are engaged and mowing. It does not do this just sitting with engine running and blades engaged, only under a load.

I took a real quick look the other day, and noticed the owners book say not to fool with high speed settings or the governor, all preset at factory. She has very limited funds and has let some people from her church work on this several times.
I can reproduce the same problem by taking my finger and moving, what the book described as the governor linkage by pushing it in just a little.

If someone has changed these settings, would that cause this type of problem? If not any ideas would be welcome.

Old man
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Old 05-02-06, 01:05 AM
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Hello Old Man,

Nice of you to help your neighbor!

The problem your describing could be caused by a couple of things. The governor linkage wouldn't be the cause. I would suspect either the rings are getting worn and allowing too much blowby, or the head gasket is blown/leaking. Removal of the head and inspection of the gasket sealing surfaces would reveal a problem there, and also allow you to get a good idea of cylinder condition. I think I'd start there.

Almost forgot the obvious....first of all, make sure the oil isn't overfilled. Also make sure the oil doesn't smell like gas, and is it SAE30 oil? If it's 10w-30, switching to 30w may stop the smoking.
Old 05-02-06, 09:46 AM
Old man
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Thanks Cheese,

I almost forgot, she told me her grandson changed the oil and used 10-30. I will drain the oil and use 30 wt and see if it makes any difference.
I said the book showed what it called governor linkage, but I believe it is the choke linkage. Looks like a paperclip type of wire that hits the throttle when pushed all the way up for start.

I can push on this and duplicate the smoke and engine miss while sitting still, otherwise it only smokes while mowing.

Old man
Old 05-02-06, 02:55 PM
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Location: Upstate New York
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The paperclip-looking linkage is in fact the choke link. By design, the choke actuation is in the throttle control. At a certain point the speed control lever comes up far enough to contact the choke linkage. If the throttle control is still in decent condition, you should notice a "notch" (position) when you move the throttle control up. This will be the full throttle position and anything past this point will gradually increase the choking action. If you have wear in the throttle control whereas there is no "notch" existing anymore it will be difficult to determine where exactly the speed control is (part throttle, full throttle, part choke or full choke, etc.). You can adjust the position of such by loosening the cable clamp at the speed control bracket and with the throttle control at the full throttle position and then slide the cable to a point just before it makes contact with the choke linkage (paperclip-looking link).

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