trouble with vanguard 18hp engine

P

P&J

Member
I have been having trouble with my engine on my skid set-up for a few monthes now and am hoping for some help. I only wash on weekends, so after it sits for the week and I start it up Saturday morning it runs fine for 1-3 hours and then it will suddenly loss some power (it is probably running at 75%) and it will stay like that the rest of the day and then Sunday morning it starts out fine and then will do the same but in less time. It sounds like it is trying to return to full power and sometimes it will while it is running but then goes back. When this first started, I found that the gas line that goes into the carb had a small leak, so I replaced it and it ran good for a few weeks and then it started acting up again. I replaced the rest of the hoses and filter and that didn't help. I brought it to a small engine shop one weekend and they listened to it and thought it was a fuel problem but they are like 2 weeks out before someone can look at it. They recommended running 91 octane unleaded (non ethenal), so I have tried that the last 2 weekends and no difference. Before I bring it back, I thought I would see if someone could help me. Also, the breather in the air cleaner seams to be blowing a fair amount of oil into it, so I am going through air cleaners about once a month.

Thanks,
Pat
 
High octane gas will do nothing but cost you extra...if it's blowing oil through the breather, it could be a couple of things. Check your oil and see if it's too full. If so, sniff it and see if it smells like gas. The gas smell will be coming from the carburetor's float valve leaking and the gas washing past the rings and into the crankcase. If the oil is at proper level and doesn't smell gassy, the breather may be bad, or you may have a bad gasket / seal somewhere on the engine. The oil cap gasket is the first one to check. Are there any oil leaks anywhere? I had a 20 hp Vanguard blowing oil out the breather because the customer lost the oil fill cap gasket. The crankcase must be sealed tightly except for the breather or it will blow out the breather.Loss of power could be due to the oil in the air filter making it run rich, need for a tune up, improper gap on the coils, improperly adjusted valves, a finnicky oil pressure switch (gassy oil isn't as thick as oil so the switch may think it's out of oil), a ground wire rubbing intermittently causing loss of spark, etc, etc, etc...


Check the oil out first, then the gaskets, put a fresh filter and set of plugs in, and let me know what you find.
 
I "think" the loss of power is coming from the air filter being clogged, But the oil that leaks up to your filter is a whole other game that does not make any sence except what Russ had to say.
 
Thanks for the suggestions, I replaced the plugs, changed the oil and filter and the fuel filter about a month ago and the air filter and fuel pump a week ago. I'll go through the other items you mentioned and let you know what I find.

Pat
 
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