Hope you guys don't mind some passing thoughts as I look at this.


Reference: Wiring diagram other thread mentioned above.

Fusable link should be added at power block under battery. What size? How much current do these things take at: normal running / inrush?

Relay size. Because of inductive load of electric motor this should be sized at about 50% over inrush current or it will be short lived indeed.

Relay quality: Should be a sealed automotive or marine unit, connectorized for easy replacement in the field. Should be rated for inductive loads.

Idiot light could be installed between any ingnition source and the fan positive wire to provide indication of relay failure or fusable link fairure. Simple transistor ciruit would do nicely or direct conection with the right bulb isolated with a diode.

 

Well you bring up some good points. But most of that is already covered, in my setup anyway. The most current the water pump is ever supposed to draw is like 8 amps. My relay is rated at 30. The water pump itself has a fuse on it's + side so that should take care of it. I've never known anybody personally to blow this fuse. I've also got my gauges and radar detector powered off of the same relay. The current draw on these is next to none, but I know it's a reliable hot when on source without having to slice the factory wiring anywhere. Thus if my gauges and radar detector go dead, I know my relay quit.

So thus I know if my relay is working without having to add any more lights to the car, and the water pump SHOULD work unless the relay quits. Should the water pump blow it's own fuse I know there is a serious problem with the water pump.

I have thought about rewiring my setup. I will do it the same as I have it now, but I will use something like an additional fuel pump relay wiring harness, most of these come with a base that a relay could easily plug into and I wouldn't have to wire directly to the terminals on the relay.

The really nice part about my setup is that with my water pump, gauges, and radar detector I've only had to tap the factory wiring in 2 places. One picks up my relay, the other lights my gauges, AND that one is even controlled by the dimmer on the dash.

 

I think your setup is good! No disrespect intended at all.

I do think a fuse (or fusable link) should be added at the battery end of the red wire to protect this wire from shorts, otherwise this unfused connection would be a problem (think accident or rubbing or something).

Do you remember what the fuse is that is supplied with the pump? This would probably be a good indication of the fusable link size. Is it a normal or slow-blow type fuse? Also do you know what wire guage they choose for the pump and how long the provided leads are?

30A relay seems like a good choice, but good to get one rated for inductive loads regardless. These have a different contact setup and design to allow for the high inrush currents involved with a motor. Really more of a long life issue, but important for something as critical as a water pump.

In your personal setup you will know if the pump looses power, but for those that don't have the same things hooked up I just thought an idiot light would be cheap and easy. Don't want to loose that pump!

 

None taken. I've lost the relay before and my car overheated very quickly. Thing is at the time I didn't have the gauges so I didn't know until I happened to see my temp gauge climbing out of range. Thus when I was wiring my gauges and needed a hot when on source I thought that would be the perfect solution.

I know the relay will fail again, it's only a matter of time. This relay is the same as my first one. This one has lasted close to a year while the first one only lasted a month. Regardless it is located where it does get wet, not to mention that it's ugly. There is a better solution out there, it's just not something I think of unless I've got the hood raised.

It wouldn't be hard at all to put an inline fuse into the hot wire, just again something I hadn't really thought about. It shouldn't be an issue unless the relay somehow shorts out internally. I'll install a fuse anyday before I install a fuseable link. The cool part about a fuse is that it would allow an easy place to disconnect power to ALL of my aftermarket wiring very easily.

Another thing that would be very easy to do is to put in a relay bypass switch. That way if the relay quits, just flip a switch and you're good to go again, no mess. Also if you couple this with a manual fan switch you can get some really fast cooldowns at the track. I'll do it someday. I am going to tear down the car again for an oil leak very shortly, maybe I'll do it then.

Know of any good sources for some waterproof relays and switches? Preferably switches that have a safety lockout so they can't be knocked into the on position.

 

Good Info :cheers: