Vanguard 16hp Low RPM's

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  #1  
Old 12-27-05, 08:30 AM
PaulUK
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Question Vanguard 16hp Low RPM's

Hi,

I have a twin Vanguard 16hp 303447 running a carpet cleaning machine.
Just recently I have not been able to reach top RPM's. I can only
reach 2k rpm. It runs on both cylinders.

I have been told that it could be a coil problem and I have others
telling me its a carb problem.

Has anyone ever come across this before?

Many thanks

Paul.
 
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  #2  
Old 12-27-05, 11:26 PM
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Does it run well when it's at the highest speed you can attain? It could easily be a problem in the machine it's bolted to. What's it bolted to? A vacuum pump? Look at the throttle on the carb. See if it's all the way open when it's running. If not, try moving it manually and see if you get more rpm. If it is all the way open, but rpm is still low, then I'd suspect the pump or whatever it's bolted to has problems....possibly bad bearings, airflow restriction, or galled vane or gear housing in the pump.
 
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Old 12-28-05, 12:30 AM
PaulUK
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Thanks for the reply.

I am going to check for back pressure today. I will let you know the outcome.

Paul.
 
  #4  
Old 12-28-05, 06:51 AM
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You won't necessarily be looking for a backpressure issue but a parasitical load issue as a possibility. In other words, is the unit the engine is attached to (by way of the crankshaft PTO) causing the trouble? You will likely have difficulty isolating this though so it may be more practical to get a professional opinion. Most repair shops will have no trouble in helping you out in this area, by simply listening to the unit.
 
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Old 12-28-05, 07:21 AM
PaulUK
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I have disconnected the blower/heat exchanger from the engine so it is running on its own. I still have this problem.

I have fuel blowing out of the carb chamber instead off being sucked down. I have checked the float/needle and it is operating correctly.

Is there any other reason why it would be doing this?

Many thanks.

Paul.
 
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Old 12-28-05, 08:32 PM
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Aha! The fuel blowing out is caused by a valve problem. Most likely, the valve is burned. (These engines run at full throttle under a good load continuously, which is a prime cause of burned valves). You can pull the valve covers off and see if everything is in place there just in case, but I'm betting an intake valve has burned on at least one cylinder. I'd have a valve job done on both heads.
 
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Old 12-29-05, 01:28 AM
PaulUK
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Thumbs up

Thanks! I will take a look later today and let you know.

Paul.
 
  #8  
Old 12-29-05, 05:49 AM
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To help reduce the chances of valve train trouble in the future, I suggest using full synthetic oil (SAE5W30) year-round as well as be sure to keep the doors open on the van so as to maximize cool air flow.
 
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Old 12-30-05, 12:06 AM
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Also, it would help if you could take the load off the engine and let it run noload for a few minutes to cool down after an extended period of running that pump. Unfortunately, most carpet cleaning setups I've seen have no way to uncouple the pump from the engine conveniently.
 
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