Riding Mower blowing lots of white smoke...


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Old 04-16-14, 03:47 PM
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Riding Mower blowing lots of white smoke...

I have a Craftsman Riding Mower with a 16 HP Briggs and Stratton engine. It first started blowing white smoke out of the exhaust a little bit when at low rpms when I turned up the throttle. Just a couple small puffs. Its an old mower so I didn't think much of it.

I was using it as normal after about 10 more uses and then white smoke just bellowed out of the exhaust. No unusual noise was made when it happened. It just keep pouring smoke out. It starts up immediately.

I pulled the plug and it was coated with crispy oil. Changed the plug, checked compression and it is at 85psi. Which is fine from what I read. I changed the oil which was very black but not thin or to thick. Clean up and examined the engine and couldn't find a head gasket leak or any oil leak. Odd....

I checked the valves and the intake was good but the exhaust was .011. It should be .005-.008. I assumed that was causing the problem by causing pressure in the cylinder on the down stroke and sucking oil into the piston. I adjusted the valves and put a new valve cover gasket. Tighten it all up.

I cleaned out the carb and rebuilt it while I was waiting for the gaskets and it sure was due. I noticed lots of oil in the air box. I pulled the header and noticed the same, but that was expected.

I fired it up for the first time and some smoke came out of the exhaust and figured it was residual from before the repair. After about 30 second it was bellowing smoke like before. I removed the exhaust thinking it was oil in the exhaust and nothing changed. The exuaust was sprinkling black oil out. Not the new but what looked like the old oil. Having a nicely cleaned engine made it easy to see that no oil was leaking from the head gasket.

Now I am stuck. I have a replacement head gasket but wouldn't there be an exterior leak as well? Since what looks like the oil black oil is spitting out should I run it and hope it clears up? I ran it for about 2 minutes and it still was pouring out white smoke.

I tried to be a thorough as I could. Let me know what you think it could be. Thank you in advance.
 
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Old 04-16-14, 06:19 PM
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I'd say the head gasket is the likely suspect. You won't see anything from the outside.
 
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Old 04-16-14, 07:19 PM
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Oh ok. I have seen a couple head gaskets go and it was obvious. Well luckily I ordered a extra head gasket with the other, just in case. I will try it out tomorrow.

Someone else mentioned a clogged breather? Would that cause the problem? It sounds unlikely to me.
 
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Old 04-16-14, 07:38 PM
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Not likely at all. The head gasket leaks between the cylinder and the chamber where the push rods pass through, causing combustion pressure to enter the crankcase and creating excessive blowby through the breather.
 
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Old 04-17-14, 05:03 PM
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Head gasket was toast. Lots of carbon build up. Thank you for eveyone's help.
 
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Old 04-17-14, 07:48 PM
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Glad to help!
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