Adjusting vaccum relief valve

Light351

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We recently purchased a prochem 405 clean and runs like a dream(very happy we shall mention) but we can only get 9hg of vacuum out of it.. I know it should be more, with 50 feet vacuum hose run, I hear lots of vacuum bleeding from the relief valve..


I tightened the spring nut, and the bolt started spinning.. Bad valve? Or just needs adjusting more? Help vacuum gurus
 

Light351

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One more thing.. At stock RPM's how much hg should we be having?
 

seagrtj

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There is nothing more than a washer and a rubber gasket inside the vac break on that blower, the bolt will spin. I would start with checking the waste tank lid gasket and make sure it is intact. then also check your waste tank filters and basket. Then check all your vacuum lines (panel to waste tank, waste tank to blower, waste tank dump hose) make sure none of those are sucking air in. The last step would be to adjust your vac relief stem spring. just crank it down a few turns and check it. under full vac load, max RPM's you should set it to 14Hg.
 

JD5150

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Prochem sets the 405 at 12 HG when new and the regular Performer at 14 HG new. 405 has two blower filters in the waste tank and the regular Performer had one. I use to own the 405 and set it at 14 HG . Ran great But do as Todd suggested
 

Scott W

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How are you measuring the lift? If you are using the gauge on the truckmount, be sure to measure with no hose attached. That is how to know where your relief is set.

The real key to how much lift you have available is to setup with hoses and wand. Check the reading. Then seal the wand and check the reading. The difference is how much lift is available to clean after subtracting for loss in your lines and plumbing.
 
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matt30577

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There's 2 hex nuts on that bolt. Are you unlocking the first one before you turn it
 

Light351

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There's 2 hex nuts on that bolt. Are you unlocking the first one before you turn it
Yes, I know the first is the adjustment nut and the second one is the lock nut..

I'm gonna try to tighten it more.. Its at 11hg no vac hoses, just sealing with my hand.. The tank seals are good! We just put new ones it and and ive triple checked them..
 

seagrtj

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I would also check the rpms of the engine as well.
 

gtech12v

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Make sure the Truckmount gauge is working properly
install a Bayco or kunkle valve
Spring valves leak before they get to a set point
 

JD5150

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I have a free flow valve that I set where I want it. I have control of the HG's to the tee but that does have repercussion's.
Example home has different carpet in each room. Has to be set accordingly. I use a Devastator filter As the job goes on the filter becomes fuller of crap so either needs to be cleaned or changed to a new/clean one. As the filter collects crap the HG's climb
 

matt30577

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It's a very high possibility that the rubber cover behind the bolt, that covers up the holes is dry rotted and can't cover up a seal anymore. I had to cut my own cover out of some rubber that I found somewhere.

The jondon mechanic told me that wd40 will, overtime, eat the rubber and make it weak. All those years of spraying it in our blowers can cause it.

Before you tighten that nut any more, I"d pull it off and see how the rubber looks on the inside
 

seagrtj

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It's a very high possibility that the rubber cover behind the bolt, that covers up the holes is dry rotted and can't cover up a seal anymore. I had to cut my own cover out of some rubber that I found somewhere.

The jondon mechanic told me that wd40 will, overtime, eat the rubber and make it weak. All those years of spraying it in our blowers can cause it.

Before you tighten that nut any more, I"d pull it off and see how the rubber looks on the inside
If you attempt to pull the relief stem out, please remove the entire vac relief from the blower so you don't drop anything in the blower. It is easy to take off.
 
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Where can one look uo what the proper vac relief is on a blower. I cant seem to find it on my 36 manual. Thanks
 

smart n kleen

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Run 150' of vac hose...run tm at operating rpm...cap it vac hose and adjust valve up or down to 14.

Sound right to you?

Thanks Brotha
I switched my to this one. It's a little more accurate.