I've a good used WP in the shop...............be right back.

Interesting results............everything measured zero ohms; impeller to body, pulley to body, shaft to body.

 

I'll try it out, just made a 200 mile trip w/porkensioner, ran great, but had lots of thoughts about no warning light /system. Porsche rebuilt pump/plastic impeller. Think squelling sound/warning light / completed circuit on existing light would not be to complicated.

Jon (water pump failure survivor)

 

After reading this thread yesterday, I had a similar idea to PorKen and I made a few sketches, however, to get the sensitivity I though of fitting a small outside diameter brass insert into the end of the impeller shaft and a small outside diameter spring loaded carbon brush.

I was looking at the bearing failure and the pully moving off axial alignment and the brush loosing contact and open circuiting. PorKen idea of fitting a variable resistance and linking it into the existing timing belt failure circuit is great for existing tensionors and PorKen tensioner. Malcolm's resistance measurements to earth at zero was also just what we needed, so this idea is taking shape.

I have a spare water pump which I will work on when I get back home into my garage in November.

Tails 1990 928S4 Auto

 

Just let me know if you want help with parts or anything.
We need this for the community.
I have plenty of old water pumps and new ones if need be.
Roger

 

I was also wondering if a hole could be made so to measure the depth of the pulley shaft to a flush portion of the top of the water pump, once the pump/belt was installed.
Then the pump could be measured at installation and then checked similarly to a flex plate check but would only require the depth gauge to be inserted into the timing cover or on top of the WP.
This would also be an easy check to do.
I think that Ken might be on a better track by trying to incorporate the belt warning system into reading another part of the pump area, with carbon brush. I still think that a precision measurement should be made prior to putting the pump into service

 

It's not clear to me. Is this an open or closed circuit?

My hope was the impeller/pulley were isolated from ground. If the impeller or pulley touched the body, it would go to ground.

For a warning which grounds when there is a problem, then I would use the coolant temp light as a warning. The nice thing about this circuit is that all years have the light, and it can piggy back the coolant sensor function.

For a warning which breaks ground when there is a problem, then the tension light could be used (with a PKsn'r). (The tension light comes on when ground is lost.)

 

I got no continuity on my old pump. That was Pump housing to pulley,shaft,impeller

I wonder if this would change with the addition of coolant or if the pump spinning would do something, anyone have a bearing that they could take apart?

 

Closed.........measuring from one of the WP housing bolt holes to various points; pulley, impeller, shaft.

Its not, at least not with the used WP I took off my engine this spring. I believe its a Porsche WP with a metal impeller.