vacuum line broken off

[dwcphoto 7]

Good day folks, I have a 518-H. It would not start yesterday, turning over without issue. I suspected the vacuum line and sure enough it was hanging free on the dash end. I noticed the fitting has broken off and is in the tube. I can't seem to find where it goes. I want to either replace the part or try to repair it. Any ideas? Thank you, David

 

[gwest_ca-(File Mod) 11,050]

Item #37 in the top right corner

https://www.partstree.com/models/31-18oe01-518-h-toro-garden-tractor-1988/electrical-system-12/

[dwcphoto 7]

Thank you! Now I know where to look. I'll see if I can pull it out and inspect. Much appreciated! dwc

[ri702bill 8,350]

DWC

You can plug the vacuum line  - a golf tee works great for this. That will get you going until you can do a proper fix .....

Bill

[Ed Kennell 38,240]

What is the purpose of a vacuum gage?       Is there a "safe " range?

[squonk 41,161]

17 minutes ago, Ed Kennell said:

What is the purpose of a vacuum gage?       Is there a "safe " range?

You get to watch that needle go back and forth when that Onan is hunting at idle. Kinda hypnotizing! 

[dwcphoto 7]

My 518-H does not have a vacuum gauge. It looks like the hose might have gone to a small, black box that says World Magnetics on it. That sound familiar? dwc

[cleat 6,078]

That is the sensor for a plugged air filter.

 

I don't have that hooked up on any of my 520's as I regularly check the air filters.

 

 

[dwcphoto 7]

Ok. So should I replace the sensor or plug the line? I know that years ago I had trouble starting the tractor and when I replaced the old, deteriorated line, it fired right up. Thank you, dwc

 

[dwcphoto 7]

Also, there's only one hose, but it looks like it has an open port in the back. They all look like they have two places to hook up a hose when I search DesignFlex PSF102 SERIES online. Thank you! dwc

[lynnmor 7,309]

1 hour ago, Ed Kennell said:

What is the purpose of a vacuum gage?       Is there a "safe " range?

 

Wheel Horse calls it a percentage of horsepower gauge.  When running with the governor holding the throttle wide open, it will read 100%.  The only practical use is informing the operator of how hard they are working the engine, and then they can decide if it should be working that hard, especially in hot weather.  If one wants to keep the valve seats in place in a 20 HP Onan then knowing how hard it is working can help you determine how it should be operated.  Only the 20 HP engine has significant valve seat issues, probably because of the more aggressive cam and more heat generated at wide open throttle.    Running the engine slower than maximum speed will cause more throttle opening and less cooling air, so that is not a good option.  Keep in mind that the lever on the dash labeled "throttle" is actually an engine speed control, the governor operates the throttle in the carburetor.

[lynnmor 7,309]

57 minutes ago, dwcphoto said:

My 518-H does not have a vacuum gauge. It looks like the hose might have gone to a small, black box that says World Magnetics on it. That sound familiar? dwc

 

 

The line from inside the air filter box goes to that switch to sense the pressure difference across the air filter media.  If the difference is too great, a lamp will come on to inform the operator that the filter is dirty.  I have only had that lamp come on one time and that was with a filter that appeared clean enough.  Holding a lamp inside showed that it was loaded with fine dust.  Those pre-filters keep the paper filter looking OK but a closer inspection is needed.

 

There is another thread discussing the sensor if you want more information.

[dwcphoto 7]

Sure, can you direct me to that? Thank you, dwc

 

[lynnmor 7,309]

22 minutes ago, dwcphoto said:

Sure, can you direct me to that? Thank you, dwc

 

Link

 

There are others as well if you search.

[Handy Don 12,237]

1 hour ago, lynnmor said:

 

 

The line from inside the air filter box goes to that switch to sense the pressure difference across the air filter media.  If the difference is too great, a lamp will come on to inform the operator that the filter is dirty.  I have only had that lamp come on one time and that was with a filter that appeared clean enough.  Holding a lamp inside showed that it was loaded with fine dust.  Those pre-filters keep the paper filter looking OK but a closer inspection is needed.

 

There is another thread discussing the sensor if you want more information.

 

Only three things I'll add:

1. if it wasn't already clear, keep that tube plugged it if isn't connected to the sensor so it doesn't let unfiltered air enter the carb

2. unless the disconnected tube is letting air bypass a really clogged filter, having it disconnected should make no difference in how the engine runs

3. the nipple on the other side of the little box is a pressure sensor; clever use of a single diaphragm--push from one side (pressure) or pull from the other (vacuum) to close a circuit

 

[Ed Kennell 38,240]

2 hours ago, lynnmor said:

 

Wheel Horse calls it a percentage of horsepower gauge.  When running with the governor holding the throttle wide open, it will read 100%.  The only practical use is informing the operator of how hard they are working the engine, and then they can decide if it should be working that hard, especially in hot weather.  If one wants to keep the valve seats in place in a 20 HP Onan then knowing how hard it is working can help you determine how it should be operated.  Only the 20 HP engine has significant valve seat issues, probably because of the more aggressive cam and more heat generated at wide open throttle.    Running the engine slower than maximum speed will cause more throttle opening and less cooling air, so that is not a good option.  Keep in mind that the lever on the dash labeled "throttle" is actually an engine speed control, the governor operates the throttle in the carburetor.

I'll check my vacuum next time I use my 520.   It has always been a winter machine used for snow removal and wood hauling.   When I had a SS tall chute on it, I always ran the Onan @ 3200 only because it sounded much better than at 3600.   I even installed a smaller drive pulley on the blower to keep the blower revs at or above design.   It always worked fine.

Due to lack of snow, I have switched to a 54" blade.      

[Ed Kennell 38,240]

4 hours ago, squonk said:

You get to watch that needle go back and forth when that Onan is hunting at idle. Kinda hypnotizing! 

And I thought it was a   CLEAN MY CARB indicator for the hearing challenged operators.

[lynnmor 7,309]

9 minutes ago, Ed Kennell said:

I'll check my vacuum next time I use my 520.   It has always been a winter machine used for snow removal and wood hauling.   When I had a SS tall chute on it, I always ran the Onan @ 3200 only because it sounded much better than at 3600.   I even installed a smaller drive pulley on the blower to keep the blower revs at or above design.   It always worked fine.

Due to lack of snow, I have switched to a 54" blade.      

You will find that the horsepower will be at or near 100% most of the time while chucking snow or mowing high grass.  We don’t realize how hard they work until a gauge shows the evidence.  When an engine maintains its speed, we aren’t aware that it is maxed out, only when it bogs down do we know that it is overloaded.