bubba964
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Briggs 20HP Intek OHV smokes after warmup and then shuts down
I have a 2007 Craftsman lawn tractor with Briggs single cylinder 20HP Intek OHV engine. Brought to a shop for a mild engine smoke problem.
Repair shop replaced what was thought to be blown head gasket. Engine continued to smoke after repair.
I have since replaced the head and push rods. Breather tube has been replaced but not breather itself.
I have removed and cleaned out the carb as well.
The engine starts up fine and runs well for 5 or 10 minutes then it starts to smoke (blueish - oil I suspect) after warm up. It eventually shuts down after another 5 or 10 minutes.
I installed an inline fuel shutoff in case the carb has a float issue so I shut off fuel when stored.
Oil has been changed with proper level of 30W.
My thoughts are a possible breather issue causing oil to blow by rings or carb issue but not sure if carb issue could still cause it to smoke after a warm up.
Any ideas what I might do to fix this?
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Roy
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Re: Briggs 20HP Intek OHV smokes after warmup and then shuts down
2018/06/04 11:44:22
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Did the shop perform a leakdown test?
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bubba964
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Re: Briggs 20HP Intek OHV smokes after warmup and then shuts down
2018/06/04 12:51:33
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He said he did but I'm not sure I trust anything this guy said. He charged me for 2 hours labor for a head gasket and he did nothing else. The spark plug was crusty and the entire combustion chamber was filthy and crusty. That's why I just bought a new head instead of trying to clean it all up and do a valve job.
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Mikel1
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Re: Briggs 20HP Intek OHV smokes after warmup and then shuts down
2018/06/04 22:20:47
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Sounds right for labor on head gasket. Like Roy I would be curious what the leak down compression tester come up with
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bubba964
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Re: Briggs 20HP Intek OHV smokes after warmup and then shuts down
2018/06/05 08:17:10
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I guess my only gripe was that I was charged to replace the head gasket when I asked him to fix a problem that isn't fixed. Water under the bridge as far as cost goes at this point.
I truly doubt he would remember the leak down test results. I simply remember him stating that he did a leak down and it wasn't a problem. I didn't know enough about the issue at the time to even ask for specific numbers. The more I look into this the more I learn about how these small engines work so if there's one positive thing that has come from this it's improved knowledge.
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Mikel1
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Re: Briggs 20HP Intek OHV smokes after warmup and then shuts down
2018/06/05 11:29:32
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Your exactly right it should have been fixed.
So how is the oil level and does it smell like gas?
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bubba964
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Re: Briggs 20HP Intek OHV smokes after warmup and then shuts down
2018/06/05 12:26:45
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The oil level hasn't changed but I also have an inline fuel shut off and I shut it off fuel line any time it's not running.
The oil smells slightly different than clean oil but I wouldn't say it smells like gas. I changed the oil before this last try so the oil only has 10 or 15 minutes on it. The level is near full and not watery.
Could excess gas be getting in combustion chamber and the smoke I'm seeing be that unburned fuel? Maybe the carb bowl is filling with fuel causing it to shut off pointing to a carb issue?
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Mikel1
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Re: Briggs 20HP Intek OHV smokes after warmup and then shuts down
2018/06/05 18:45:20
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I notice you said bluish smoke earlier. Is that still correct? After it shuts off, can you start it right back up?
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bubba964
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Re: Briggs 20HP Intek OHV smokes after warmup and then shuts down
2018/06/05 20:08:17
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I would say blueish-blackish after warm-up and when it shut off I couldn't get it started after that. I haven't tried to start it since but I will try tomorrow and reply with results.
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bubba964
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Re: Briggs 20HP Intek OHV smokes after warmup and then shuts down
2018/06/06 13:15:36
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Last attempt a day or two ago at running the tractor, it ran for 5 or 10 minutes and started smoking and within 10 more minutes it shut down and would not restart.
I attempted to start it this morning and it started right up. Same MO, 5 or 10 minutes and it started smoking light blueish smoke. I did not run it until it shut off but I wouldn't expect anything different. The smoke is leaving a black haze on the area around the muffler and hood.
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Mikel1
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Re: Briggs 20HP Intek OHV smokes after warmup and then shuts down
2018/06/06 17:21:56
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Yeah your burning oil. Are you spitting oil out of crankcase breather hose when running where it connects to the air filter housing?
Spark plug most likely fouling out causing it to shutdown.
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AVB
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Re: Briggs 20HP Intek OHV smokes after warmup and then shuts down
2018/06/06 17:31:33
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Even a bad intake valve stem seal can cause one to smoke. Also can be problem with the main jet o-ring if it is a Nikki carburetor though the smoke is usually a little darker. Excessive blow-by usually shows in the intake as excess oil.
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bubba964
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Re: Briggs 20HP Intek OHV smokes after warmup and then shuts down
2018/06/06 18:28:37
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It is a nikki carb and that was going to be my next step. Carb replacement. It's like $20 so not a terrible expense. As it runs it does start smoking heavier.
I replaced the head and pushrods so valves should be ok.
I did remove the PCV tube and held a white paper towel in front of it and didn't get anything on it.
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Mikel1
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Re: Briggs 20HP Intek OHV smokes after warmup and then shuts down
2018/06/06 19:55:16
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That's what I keep thinking, it is blowby. I would have liked to know the leak down tester numbers. Has the crankcase breather been tested? Where are these $20 Nikki carbs at?
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AVB
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Re: Briggs 20HP Intek OHV smokes after warmup and then shuts down
2018/06/06 20:43:02
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Mikel1
Where are these $20 Nikki carbs at? They are Chinese aftermarket clones. Personally I rather stick with the Japanese Nikki carburetor. At least I know I can get gaskets and other parts for them. Plus I had bad result trying the clones here that customers had brought and wanted me to install. The OP need to make he get the right version too as there gravity fed and pump fed versions.
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bubba964
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Re: Briggs 20HP Intek OHV smokes after warmup and then shuts down
2018/06/07 17:56:38
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I'm sure AVB is right regarding it being a clone for that price. I'll give it a shot though. I was going to look at the breather itself too. I know breather tube is OK. Outside of breather and possibly carb, it seems like rings might be next step. I have another Encore 32 walk behind with a sulky so I'm not desperate to get it fixed but with everything else I have to do around my place pulling the engine and pulling out that piston may become a pet project for a rainy day.
I'll try the carb and look at that breather and let everyone know how things turn out next week some time. Thanks for everyone's ideas and help.
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Mikel1
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Re: Briggs 20HP Intek OHV smokes after warmup and then shuts down
2018/06/08 20:36:19
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Sounds like a plan, let us know
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bubba964
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Re: Briggs 20HP Intek OHV smokes after warmup and then shuts down
2018/06/12 17:44:31
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OK, so I replaced the carb. Still smoking after warmup. It didn't shutdown on me this time and I think I ran it longer than I ran it last time when it did shut down. The smoke was getting pretty heavy so I didn't want to run it too long. I would say smoke was definitely white indicating oil burning. I took air filter out and had smoke coming from intake side of carb and I also took out dipstick and had smoke coming from oil fill tube. I smelled the oil and I wouldn't say it smelled like gas. The oil level was definitely lower than when I started. I probably ran it for ten minutes and started with oil level in between lower and upper limit of the hash marks on dipstick. When I stopped oil level was at bottom limit on hash marks.
I did not remove breather because it looks like I have to remove flywheel to get it off. I can see one bolt for breather cover but the other section of the cover goes under flywheel. Is it time to pull that flywheel and look at that breather?
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Mikel1
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Re: Briggs 20HP Intek OHV smokes after warmup and then shuts down
2018/06/14 20:42:30
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You don't have to take breather off. If you have a small party balloon, you can attach it to the hose. While running it will blowup some or if you have alot of blowby then alot. Kinda cool or you can suck and blow thru the hose. Hopefully your not allergic to the hose, I'm not sucking on oily hoses,lol. Doesn't take but a minute to check, if that's good then most likely a ring problem
post edited by Mikel1 - 2018/06/14 20:53:53
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bubba964
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Re: Briggs 20HP Intek OHV smokes after warmup and then shuts down
2018/06/16 11:38:02
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I think I'll do the balloon trick today. I'm not keen on getting my lips anywhere near that oily engine.
What would be the expectation for a positive result? I plan to do it at startup with cold engine and also do it once it heats up since that's when the smoke starts spewing.
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