V4 Water Pump Q&A w/Dave Sage

Date: Dec 19, 2014
Re: magnetic drive water pump:

I have a question for those who have built the magnetic drive water pump.
Have you checked the operation of your water pump and confirmed it is moving water? Perhaps did you happen to check it off the engine.

 I built the pump for my V8 version of the V4 several years ago and I'm pretty sure I saw it moving water - at least a few bubbles went by in my clear hose. Now I'm not so sure it's working - or ever worked properly.

 I took it off the engine and cleaned it up and tested it off the engine and sure enough it doesn't pump. The magnetic coupling is not the issue the impeller is moving and you can tell when the magnets "cog" when they slip.

 I recently needed another pump for a new engine so I built a slightly larger version with a direct drive shaft and made (what I think) is a better impeller. But still no pumping action.

 I looked at pictures of some others that people have built and best I can tell they look like mine and appear to be what's in the drawings so I don't think I interpreted anything wrong. I'm not sure why it doesn't pump.

 I'm very interested to know if there might be something wrong with the design although if Jerry made it probably worked. So it's probably something I've done wrong (twice).

 Has anyone else made one of the pumps and actually confirmed operation.

Thanks

Sage

--------------------------------------- Dec 22, 2014

I think I figured out my problem. Off the engine I'm turning the pump too slow. I was using my battery drill which only turns 580rpm. I put it on my AC drill and at 2800 rpm it pumps fine. I think on the engine it probably turns at least 1000rpm. All I have to do is get it primed properly on the engine.

Sage

-------------------------------------- Jan 7, 2015

I found that as the pump is designed does not provide adequate magnetic coupling for the torque required and looses magnetic lock at normal operating speed when pumping 50/50 ethylene glycol coolant.  The torque requirement of a centrifugal pump increases with RPM.  This being said, I found a solution that worked well for me that did not require remaking the pump. I added another set of magnets to the drive, placed between the original set of magnets. The second set of magnets were placed with their magnet polarity opposite that of the first set.  This provided far greater magnetic coupling and holds thru out the operating RPM.  Also it should be noted that once magnetic lock is broken no torque is transferred and the pump comes to a stop and no coolant is pumped. Magnetic coupling can not then be restored without coming to a complete stop and restarted.    thank you,  Wayne Dellinger  717-244-8886

V2 crankshaft and tailshaft bearing placement confusion resolved

Q&A e-mails with Ernie (Q) from South Florida and me (A):

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Q: Sheet #22, Crankshaft – The bearing diameter portions of the shaft as noted on the drawing are .500” & .437”.  However, the bearing used on the shaft have inside diameters of .500 which is OK, but the other is (supplied by you) 12mm. However, 12mm = .472”, therefore, the .437” shown on the drawing must be wrong; it should be .472” or 12mm.  The bearing supplied is 12mm ID x 21mm OD x 5mm thick.

A: The crankshaft in the V2 is not like a traditional one-piece crankshaft where you have two ends with the connecting rod throw in the middle.   Basically, this shaft has just ONE end.  On the other side of the crankdisk is the tailshaft.  Both crankshaft bearings are mounted to the crankshaft, but on the SAME side of the crankdisk.  See the crankshaft housing on page 13.  Both crankshaft bearings fit in the housing, and the crankshaft slides into BOTH bearings.

The other side of the crankdisk is the tailshaft (Pg 10), supported by two bearings, with the inner tailshaft receiving the 12mm x 21mm x 5mm bearing, and the outer tailshaft will receive the .250 ID x .500 OD x .187 bearing.

Q: Look on page #18, the figure in the upper left. Note the tailshaft (it is .375” dia.) The ball bearing is 12mm ID x 21mm OD x 5mm thick.  12mm is .472”.  How does a .472 dia. bearing fit a .375 dia. shaft?

A: Both crankshaft bearings are .500 ID, and they BOTH slide onto the .500 diameter section of the crankshaft as illustrated at the top of page 22.

The 12mm ID x 21mm OD by 5mm bearing is NOT mounted on the tailshaft, but rather, it is mounted on the Tailshaft Crankdisk, bottom right on Pg 22 (thus the .472), and the tailshaft is inserted into the crankdisk (thus the .375 ream).