Wilcox Crittenden Head Mate dry mode inoperable after rebuild

[Saqqara]

I have emailed Thetford which is the current supplier of the rebuild kit for Wilcox Crittenden Headmate heads, and they have been no help.

I must be reassembling the pump improperly, either the cam assembly, or the valve assembly. It flushes just fine in normal mode, but in dry mode it pumps super hard like pumping against a captive chamber of air, and water continues to flow. I loosen the packing nut completely on the handle, it's not friction that is the problem.

Does anyone have photos or better instructions for assembly of this pump? Kit came with an exploded diagram lacking detail.

The first thing I have noted is that the inlet valve flapper assembly as shown in the picture is installed differently than the old one (unfortunately I didn't take pictures during dis-assembly with my messy hands, but this is evident from marks in the rubber from the housing). Looking at the cam and vacuum breaker finger I can't imagine it going back as the diagram indicates as this would provide rough/uneven surfaces for those parts to contact. However I've tried a couple different orientations with no success, including putting back the old valve assembly.

Also I suspect the cam/vacuum breaker finger parts could have been put back wrong, but the way they are in there, and how they mate together seem the only way logical. It would seem the finger, and the cam lobe should both be pushing forward on the two valve concurrently, since that would serve to open one and shut the other.

Greg
Laguna 33 "Star of the Orient"
Slidell, LA USA

[Saqqara]

Well, I have it working with the old inlet valve flapper assembly. The issue seems to be that the cam was blocking the dry mode lever from moving completely forward (completely horizontal). I suspect the new valve flapper is too thick to allow the cam to move down, or that I had torqued the housing on too tight. Also, I put the old part in as it had been before, which conflicts with the diagram.

I have seen a rant on another forum where a guy claimed that Thetford knowlingly had the wrong valve flapper in this kit for older HeadMates and it could cause the housing to crack. I'm not finding it at the moment, but I don't see the two washers vs one problem he described when I compare my old flapper.

[HopCar]

"It would seem the finger, and the cam lobe should both be pushing forward on the two valve concurrently, since that would serve to open one and shut the other."

That's correct. It sounds like the finger isn't opening the discharge valve to let air in on top of the piston and a vacuum is being created making it hard to push the piston down. It's the vacuum you feel not a "chamber of air".

Since it works fine in the wet flush setting, it must be a problem with the cam / finger assembly. Check the set screw that prevents the handle shaft from rotating inside the cam / finger assembly. If that's loose, the cam and finger won't work.

Another problem is that the discharge valve sometimes sticks to it's seat and it takes some force on the finger to break it loose. The handle should rotate a little below horizontal to be sure the discharge valve is open. This is not a likely problem in a new rebuild.

[Saqqara]

Yes, it would have been a vacuum. I could let go of the handle and it would rise on its own. I didn't know how far the lever was supposed to move forward in dry position, it was stopping way too soon. The set screws are threaded into the lever shaft on my unit so no slippage possible.

Not sure why the cam wouldn't rotate all the way forward, can't say for sure it is the new valve flapper that is the problem since once I got it working with the old one I quit. I was a bit surprised how far forward it went, and it felt and sounded better (could hear the finger engage the valve). If I get curious as my list of chores grows shorter I'll try to figure it out. In the meantime I'm back in business.

Thank you for your response.