Holding tank pumpout

[Phil P]

Relatively new to boat, I have a '91 Hunter 375. It has the original aluminum holding tank and a Jabsco head with the new locking pump handle.
1. For pumpout I've opened the seacock, kept the "switch" to wet flush, and pumped the handle as the vacuum from the pumpout station operated pumping fresh water into tank at same time as I am sucking out waste. Is this correct?
2. My through-hull vent was clogged and I removed it and cleaned it out but still, when I pump out the tank I can hear the tank walls getting sucked in and releasing with a bang when suction stops. This cannot be good. Is there another vent or is the vent hose clogged at the tank? How does one get to where the vent hose connects to the tank? It doesn't seem to be accessible.

 

[Ron20324]

Peggy would have said, "told ya so!", so put in a larger vent line and fittings. The larger, the better. Otherwise the pumpout is sucking out your head pump parts.

 

[Steve Dion]

When we pump out we remove the deck fitting and place the pump-out fitting over the fitting and pump out the tank. If you have a different setup you may need to change valve settings.

Our tank is set up so everything goes directly to the tank and anything in the tank can only be discharged either through the deck fitting or through the macerator.

Putting in a larger vent line is often not an option. I would suggest that you eliminate any clam shell vent with a straight through mushroom through hull fitting. This will allow you to flush the vent line every time you pump out.

I would suggest that you clear that vent line before you do much more pumping.

 

[Steve_Catalina]

Phil.

Keep your thru hull to the head closed.
If when pumping out your tank walls are collapsing only one thing can be wrong, your vent is still plugged. There is no other possibility.

Additionally, not to be the bearer of baaaaad news, but if your aluminum or stainless tank is original you are are borrowed time, 21 years is a long time for a metal holding tank to survive.

Search on this site, there are 100s of pages on holding tank vents, metal tanks and how to resolve and fix any and all HEAD issues.

Peggy Hall the retired "Head Mistress" did us all a great service for many years and all of her positive information remains on this great site.

Steve

 

[McZube]

When my vent tube was clogged I replaced the tube. I wasn't willing to bother with trying to clean it out to save a few dollars.