XP 25 freshwater pump problem

[Terry Forshier]

I am almost there. I have the new orbendorfer Pump and have it on and in place. I am going to change out a hose or two and fire it up later today. Hopefully it will work.
For some reason I do not seem able to find these work projects on the site. Like the one where the seals were upgraded and the one where the pumps are being replaced. I search but get threads and parts of discussions. I looked under projects but did not find what I am looking for.
What am I doing wrong? I seems to me I had an email months ago that we had a new search engine mechanism to loacate these things but I am having no luck. I have the disc that was sent to me from the assiociation but have not been through that yet.
Terry

[Ken Juul]

The rebuilding the Oberdorfer pump is in the May 2002 Technotes.

The Knowledge Base is located at:
http://www.c34.org/tech-notes-index/technotes-excel.xls

[Terry Forshier]

Final report.
Nothing is easy and even the simplest job takes longet than you expect. So was this final phase. I hooked up the hoses and started the motor. Water started coming out the exhaust then quit. Shut down the motor. Looked it over from the front. Looked ok but no water coming out. Took off hoses. ??did I have them reversed.? Then a piece of impeller fell out of the hose into my hand. ??
So now I think, CR__P I ruined the impeller. So I take the face plate off. No. all looks in tact? so where did this come from. Went in and got the old pump off the workbench. Opened it up. Impeller still in tact. ?? Must be the ghosts again. (another story)
So put it all back together with hoses reversed. Started motor. Nothing pumping. ?? Opened up face plate looked at pump. looks ok. Opened up old pump again looked at impeller set and both look the same. Reasoned that the fresh water had to come from the top around and be forced into the bottom and out. Reversed hoses back to original. Started motor. Nothing.  Now really bewildered. Sat on cabin floor. Though a few minutes. Reached around head door into locker and opened the thru hull fitting I had closed when I switched hoses. Started mortor.  YES, Viloa, music, pump is pumping water. FWE pump pumping with no leaks, Raw water not leaking anywhere. All is well again in Mudville and Casey did not strike out. Ran until heat came up to normal.
The End.

[Craig Illman]

Ah! reminds me of my impeller change last weekend where it wasn't until the third time taking the stinkin' Sherwood apart that I noticed I had dislodged the shaft key and the impeller hadn't been turning.

Craig

[Ron Hill]

It's always a good idea to suck the raw water up to the pump and fill the intale line after you change out an impeller.  It's also much easier on the pump and the new impeller.  A thought

[Craig Illman]

Ron - Suck how? with a wet/dry vac?

Craig

[Ron Hill]

Craig : Suck the water up to the raw water pump with a "Par Boy" pump or attach an extra piece of hose and literally suck.  Then shut off the thru hull so the water stays in the line, put thumb over the hose and reattach to the inlet of the raw water pump.  Turn on the thru hull and you're good to go. 
This was one of my Mainsheet Tips from 12 or 15+ years ago. 

[Craig Illman]

Ron - Thanks, I think I'd rather use my 2 gal wet vac than get a mouthful of Puget Sound! I hope with my recent Globe install, I can go a couple years without tackling another change. When the seals eventually go, I'm strongly thinking Oberdorfer with a SpeedSeal.

Craig

[Stu Jackson]

1.  Oberdorfers do NOT need a Speed Seal - save unnecessary $$ spending - the screws for the faceplate are on the front of the pump housing.  Just another reason to use an O pump

2.  Don't suck, don't pump, use a funnel with some water in a glass from the galley sink into the hose and slap it back onto the barb and tighten up the hose clamp - sometimes "less is more" -- no pump, no sucking, just a simple gentle wrist action into the funnel.  I've used this to "burp" the engine on the freshwater side and have written a Tech Notes and sent it to Mike V.

[Mike Vaccaro]

Another interesting pile-on:  As the face plate on the Oberdorfer wears, it's possible for the mounting screws to actually "bottom-out" in their tapped holes and thus the plate is not pulled tight against the housing.  This is exaserbated if the pump face has been honed to ensure a flush seal.  When this happens, the pump is no longer "self-priming" and will not draw water unless it's primed (either by sucking or filling!).  The inexpensive fix is four #10 split washers under the screw heads that allow for a bit of extra bite and allow the cover to seat properly against the gasket.  Although conventional washers will achieve the same effect, split washers should be used to prevent loosening due to vibration.  If you do use a SpeedSeal, the knurled screws are the same length as the stock Oberdorfer screws and it may not make a seal either.  Washers or shortening the screws will allow for a proper seal. 

There has been some discussion on this board about raw water pumps that won't self-prime--if the system is plumbed and working correctly, these pumps should always self-prime.  Ron is correct that impellors don't benefit from being run "dry..."  If you don't have exhaust water within 30 seconds of cranking, it's time to shut down and investigate.     

We learned this the hard way after re-plumbing, double clamping, hand priming and anything else we could think of over a couple of years trying to figure out way the raw water pump wouldn't self-prime with a stock plate or a SpeedSeal...

We carry a spare freshwater pump on board (after the first failed and cost us a weekend vacation as well as a six hour upwind slog back to the dock under sail!).

Cheers,

Mike

[Stu Jackson]

Good point, Mike, and we carry a spare new faceplate, too, -plus you can always make a gasket out of paper bag material.

[Ron Hill]

Guys : Actually the Oberdoffer pump face plate has two sets of screws - 2 are longer that the other 2?  I asked Depco which went where and they couldn't answer - so buy the shorter ones!
Also any machine shop can reface the face plate on the "O" pump - that's what I do.  A few thoughts.