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Old 07-22-2016, 03:18 PM   #1
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Jabsco Hand Pump Hard Down Stroke

One of our relatively new (< 2 years) Jabsco hand-pump heads has developed an annoying quirk.

Set to "wet bowl" it works fine.

Set to "dry bowl" the up-stroke works fine, but pressing down offers stiff resistance like you're fighting either a vacuum or trying to compress something. Forcing it down slowly against the resistance for one or two strokes frees it up. After that, the bowl pumps dry with little resistance, as it always had (and as the other, identical pump, always does.)

I know these are simple devices, and I also know the position of one of the little flappers inside could make all the difference. Backing out four screws takes off the top of the pump, so that's not difficult.

What I'm pondering is, when I get in there, what should I be looking for?
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Old 07-22-2016, 04:14 PM   #2
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Sounds like you have problem that's very common in Jabsco manual toilets--a failed wet/dry cam. The wet/dry "valve" is actually just a little "gate" (the cam) that the lever swings to block or unblock the flow of incoming flush water. Due to either a tooling or mfr'g flaw, it hangs up...creating back pressure that feels like pumping against a clog or blocked tank vent, except it only happens in one mode--usually the wet mode but not always.

The cure: replace the wet/dry cam assembly.
Jabsco often sends out a new one for no charge...but then you have to take the pump apart to replace it, which can be a PITA and really messy because you can't flush water through the pump to clean it out before you take it apart.

So my advice: just replace the pump instead. It's prob'ly overdue for a
rebuild or at least a joker valve --and besides, modern Jabsco toilets have fairly short lifespan--they're purposely made to be "disposable" like everything else today. A service kit costs almost as much as a pump, which doesn't cost that much anyway...HopCar will give you a good price...and swapping it out only requires removing and replacing the 4 bolts that hold the pump on the base and two hoses, which beats the socks off taking the pump apart!
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Old 07-22-2016, 07:58 PM   #3
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We had a similar problem with the downstroke on our Raritan. I traced it down to a bottle cap lodged in the 90 deg elbow from the sani line into the top of the tank. Now who would have flushed a perfectly sized plastic bottle cap down there?
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Old 07-22-2016, 08:06 PM   #4
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Quote:
Originally Posted by Trawlerpeople View Post
We had a similar problem with the downstroke on our Raritan. I traced it down to a bottle cap lodged in the 90 deg elbow from the sani line into the top of the tank. Now who would have flushed a perfectly sized plastic bottle cap down there?
Someone ripping the cap off a bottle with their teeth. Bear Grylls style?
With our Mk3 Jabsco, most things are fixed with a new kit, but as Peggy says the difference in cost between a new pump and a kit is minimal, plus you get a new barrel.
Doesn`t take long to spend more on kits etc than the whole head cost initially.
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Old 07-22-2016, 08:30 PM   #5
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We were thinking of switching to an electric head someday but I know nothing about them.
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Old 07-22-2016, 09:38 PM   #6
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I have had the tough push on the downstroke occasionally. It has always responded to a resetting of the lever: first return to the other side (water in) then back to water out and away it goes.
That is only on the aft head, where I replaced the whole pump at last maintenance. On the fwd head I just put in a kit at the same time and haven't had that issue at all.
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Old 07-23-2016, 06:36 AM   #7
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Thanks for the quick reply Peggy! I do have a spare pump, since as you say it's easier and not much more expensive than a rebuild kit. And if it's a manufacturing defect, that answers my question about whether there's something I just need to go in and adjust.

My own experience sounds more like Keith's. It's not all the time, but more often than not lately. It sometimes responds to flipping the lever, sometimes not.
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Old 07-23-2016, 08:17 AM   #8
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"So my advice: just replace the pump instead."

So right , it was garbage when new.

Sadly a good marine head is not cheap, I like the Groco K , but there are one or two that compare.

The best working of the near cheapos is probably the Lavac , which can easily be up graded with a better pump.

Lavac Marine Toilets

Lavac Marine Toilets


The patented vacuum flushing system has not been equaled by any other marine toilet manufacturer. After use, close the Lavac seat and lid and then pull the ...

For a new boat , just have it out with the interior designer and use an RV style Sealand , waste leaves with 1/10 the water , so the holding tank is "larger" .

Personally I try to avoid any/every item from Jabsco..
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Old 07-23-2016, 10:11 AM   #9
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My own experience sounds more like Keith's. It's not all the time, but more often than not lately. It sometimes responds to flipping the lever, sometimes not.

He's actually having exactly the same problem you're having and sooner or later flipping the lever will cease to work.

This would actually be an excellent time to upgrade to a good toilet. Raritan's new PH SuperFlush uses the tried and true PH II pump and has a base designed to be an identical match for the Jabsco mounting bolt pattern. Defender is the only retailer who has it in stock yet...Hop-Car can get it, but I don't know if he can match their introductory price Raritan PH SuperFlush Manual Toilet at Defender

Or if you want to stick with a manual toilet, but would LOVE to be able to flush with pressurized fresh water, the Raritan Fresh HEAD is the only manual toilet on the planet that's designed to use pressurized fresh water. Available as either a full toilet or a "conversion" that also has a mounting bolt pattern that's identical to Jabsco. Raritan Fresh Head at Defender It's been on the market for 2 years now, so get a quote from Hop-Car for it.

Or...If you think this would be as good a time as any to upgrade to electric, we can talk about the best options for your boat.
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Old 07-23-2016, 11:26 AM   #10
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Thanks for all the advice Peggy! I have a Raritan PHII that does this (hard to push on downstroke dry). Is it a cam you say? If I remember right there were'nt any cams but a barrel with o-rings that turned. I recently resealed the pump and it was working very well until yesterday. Is this common? (Edit) OOps I see you were talking about Jabsco. sorry.

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Old 07-23-2016, 12:41 PM   #11
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When you push the piston down, something has to come in on top of it or a vacuum will form making it hard to push down.

When set to wet bowl, water comes in through the inlet hose to fill the space above the piston. If it is difficult to push down when set to wet bowl, look for a blockage in the clean water intake line.

When set to dry bowl, air comes in through the toilet bowl rim to fill the space above the piston. If it is difficult to push down when set to dry bowl, look for a problem with the wet/dry selector mechanism.

If the piston is hard to push down in both wet or dry bowl, you have a blockage in the black water discharge line.
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Old 07-23-2016, 12:45 PM   #12
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Peggie, thanks for the referrals! As always I recommend that anyone who owns a boat should own Peggie's book as well. I thought I knew a lot about marine toilets before I read her book. I was wrong. Read the book.
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Old 07-23-2016, 02:06 PM   #13
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I have a Raritan PHII that does this (hard to push on downstroke dry)....

I don't think so, Parks...his symptoms exactly fit an air valve problem.

The air valve is part #1203W...the little square plug on the front of the pump. It has has a check valve inside that opens on the downstroke of the piston to allow a little air to come into the (unused) top half of the pump cylinder to stop the "vacuum kick." If this check valve doesn't open to allow air into the top half of the pump cylinder, the handle becomes very difficult to pump in the dry mode and wants to jump back and smack you in the face. This ONLY happens in the "dry" mode. The problem, that little check valve is stuck.

The cure: Straighten a paper clip and poke the wire into the hole in that little plug to push it loose...it's spring-loaded and you should feel it move in and out when he presses the wire in there. If that doesn't fix it, remove the square plug (it threads into the pump) and clean it. Wrap some teflon tape around the threads to seal it when you put it back. If THAT doesn't fix it, replace the air valve.
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Old 07-23-2016, 03:15 PM   #14
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I agree Peggie. Air has to get in on the dry down stroke. The PH uses a little air inlet valve and I'm pretty sure the Jabsco uses a cam to hold open the valve between the bowl and pump to let the air in. I know that's how the old ones worked. I don't think I've ever taken a new Jabsco apart. I should look at the exploded drawing to be sure.
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Old 07-23-2016, 04:26 PM   #15
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Thank you so much Peggy & HopCar! I will try this soon as I get back down to the boat.

Kevin
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