Delaval 76 issues

[PerryFamily]

Having issues with a gas powered 76

This pump had a big drink of sap due to a releaser failing to dump

All of the sap was cleaned out of everything including the reclaimer

I rebuilt the pump with new vanes, bearings and seal

Now I'm getting oil in my moisture trap??
How can that be, it's on the suction side?
It doesn't make any sense to me
It was suggested that a new check valve vs swing check will fix this?

It also built terrible vacuum towards the end of the season, very erratic and rough running
Any suggestions?

[BreezyHill]

Why did she need new vanes?

Sounds like the rotor is rusting or it has a sugar coating on the rotor. This will cause the vanes to stick and give poor vacuum and variable vacuum depending on temperature of the pump.

Oil to the trap is occurring due to variable vacuum from when the releaser cycles. a swing check will help with this only slightly if at all. The issue is when the releaser is filling your vac level will be high until the releaser opens the empty chamber to be evacuated of air. At this moment the air rushes to the pump and will be sucked thru the center of the pipe the fastest. Oil that is sitting on the bottom can easily flow toward the trap past the check valve. To eliminate this from happening an over size vac line can be used to trap the oil in a low point and a petcock can be installed as a drain.

This is one of the safety affects of a moisture trap...protects the sap an releaser from oil contamination.

The new vanes are likely Kevlar and may have scores on them from the sugar residue. Not a problem just clean the rotor and the housing and spray down with WD 40 to keep the surfaces clean an rust free.

What was the clearance of the at top dead center an PE?

Ben

[PerryFamily]

the vanes were put in when I put new bearings and seals in it

the rushing air when dumping makes sense, the other 76 I had was on a double vertical releaser so there was very little loss of vac when dumping therefore no oil in that trap

No idea what the clearences were. I cleaned it out with brake clean and made sure the vanes moved freely. The housing is scored some maybe it needs a honing?

[BreezyHill]

Scored housing is a killer of vac since the vanes can not compress the air. The scores allow the air to go to the preceding chamber or to the tailing chamber. I would hone the housing and flip the vanes since the scoring will mark the vein's frictional edge.

Honeing is very simple and takes very little time to do a perfect job.

Ben

[ennismaple]

If your check valve isn't working properly the vacuum in the moisture trap/releaser/tubing can suck oil back into the trap when you turn the pump off at the end of the day. I've been told you need to maintain the check valve - but have never done it myself. If you sucked sap back into the pump it's probably stuck partly open.

[PerryFamily]

Makes total sense ennis about the check valve

Breezy I think the housing may be beyond honing but I can't remember. If it is maybe I can take it to a machine shop and they can fixer it.

Thinking of replacing this all together, maybe for s guzzler or something like a small gast pump off of a generator

[BreezyHill]

I have never seen a pump that was past honing with a Kevlar vein...unless you dropped part of the race into the pump but that usually blows a breaker or smokes a belt before massive damage is done.

Brass checks are the best for our use.

[BAP]

Check to make sure the shaft is not spinning inside the rotor. The shaft is a press fit into the rotor and may or may not have a pin helping to hold it in place. I have seen the shafts break free and spin in the rotor causing low or erratic vacuum. If that has happened a machine shop can make a new one that has a press in fit. I have done that a couple of times. Also, when you put the new vanes in, did you soak them in vacuum pump oil for a while before installing them? They should be soak first so they absorb a good amount of oil so they are well lubricated.

[PerryFamily]

BAP this pump did have the rotor spin on the shaft 2 seasons ago. I chamfered the drum, warmed it up , welded it, insulated it to cool slowly. It seemed to work but possibly it cracked I'll have to check. I didn't soak the vanes but did give them a healthy dose of oil and everything moved freely. I'll have to pull it out and check it