HOME      Email

HyVac 1 Vacuum Pump Not Working

HyVac 1 Technical Support

Please read complete once, before starting.
Because of some of the end applications, we get a lot of calls about this same problem.  It seems to go like this, “I have a HyVac 1 and it doesn’t make enough vacuum anymore.” Or “I have a HyVac 1 and it is locked up.”  The main culprit is water contamination.  The main applications seem to be asphalt-testing labs, soil testing and vacuum distillation.  This is a good choice in a pump for the application, but more care needs to take place regarding replacement of the contaminated oil.  This is especially so when the pump is going to be put on the shelf for a while.

When the pump is used to de-gas / de-aerate the asphalt mix or soil mix or distill product often times the water covering the mix is turned into a gas phase and pumped by the vacuum pressure and ends up in the oil sump.  You are not doing anything wrong, it is just what happens (This is physical chemistry).  Using traps like desiccant traps are a waste of time to implement in our opinion.  Desiccants do not stop water under vacuum.  Better solutions include more frequent changing of the oil.  Leave the pump run 24/7, no problem with our pumps, they are for continuous duty.  It is more difficult for rust to form with the pump running, if the surface that rust would form on is in constant motion then there is less opportunity for scale buildup.  The most costly solution and best, is by purchasing and installing a “cold trap”.  These traps freeze the water before it gets into the pump.  They turn it from a gas phase back into a crystal state (frost).  This process technically is called “sublimation”.  The traps do cost some money, sometimes even more than the pump but do protect the pump.

Ok the problem is already here and our pump is misbehaving.

Not enough vacuum but pump is running.
Unplug the pump from the electrical source.
Drain the oil.
Rotate manually the pump pulley and drain oil again.  Do it again.

We do this because oil gets caught in the trap of the pump.  This is the design of the pump and we need to get “most” of the oil out so humor us.

 Chances are that one of the vanes in the pump, usually the exhaust vane, is stuck in the up position.  To review this, you need to remove the 4 screws on the very top of the pump and remove the top cover.  Remove the cover gasket if it is not adhered on. 

There will also be a sheet metal baffle plate that is a little piece of sheet metal with 2 screws in it.  Remove this animal also.  If you drop the screw in the pump, don’t have a heart attack, but upend the pump later and make sure it falls out.  Once the plate is out you should be able to see the top working part of the pump.

Manually rotate the pulley while looking in the top of the pump.  You will see 2 springs attached to 2 lever arms.  These lever arms go up and down as the pulley rotates.  If one is stuck, it doesn’t move up and down with the action of the pump.  Probably this is because of rust formation in the slot the vane travels in.  When we make these the vanes are made to a thickness tolerance of -.0005” so a little rust can stop the function of the vane going up and down.  Don’t worry we have a relatively simple fix.

Remove the springs from the lever arm and spring post.  Put aside.  If the spring is not there or broken, you may need a new spring/springs.  Sometimes if the springs aren’t there it is may be in the bottom of the pump oil case.  Remove by upending the pump so the oil drains out and check for spring/s.

Move the lever arms out of the way so you can see the 2 vanes.  These are the thin piece of metal that generally go up and down in a slot.  Care should be taken as one of the vanes goes in a special way, the one with the bevel cut on it.  If the vane comes out of the pump please immediately, before you let go of the pliers, mark which end of the vane is into the pump and which way it faces on the pump.  The perpendicular specification is important and if put in backwards the vane may not make good vacuum.

Using a pair of blunt nose pliers it is possible to pull the vane up not out of the slot but we really just want to manually actuate it up and down so that it rides freely in the slot as it would if just the spring pressure was applied.  The pump can be manually actuated to allow for the maximum penetration of the vane down into the slot.  Do both vanes, there are two.  This is a gentle but firm effort, not a gorilla thing.  If the vanes will not actuate to full extension into the pump try using some solvent or degreaser, whatever so you can get the vane actuating down into the slot.

With the vanes running smooth re-hook up the springs to the lever arm and spring post.  Manually actuate the pump using the pulley to see if vanes are now going up and down with spring tension only.  If doing good, replace the baffle plate. Fill the pump with oil.  Replace the top cover and gasket.  Plug it in and check it out. This generally fixes the pump. 

On conclusion please review oil change interval for the pump and increase frequency of changes.  When the pump is put away change the oil fully, like you did in this exercise.

If the pump is totally locked up the vane may be stuck in the down position not allowing the rotor to move around.  In this case the pliers need to remove the vane so we can use a little scotch brite on it to clean it up. Remember to fully document the vane removal which side is what facing what. 

If after vane removal the pump still is locked up tighter than a tick chances are you have to send it to us for a rebuild / cleaning.  Call us for a Return Goods Authorization (RGA).


11/27/2005 ©Copyright HyVac Products, Inc. All Right Reserved
Toll Free 1-800-628-0850