Is there a way to test if water pump is pumping?

[Jimmyvonviggle]

I thought I had solved my overheating issues by replacing an otterstat and a relay, but no such luck. My fans do not want to turn on consistently. So today I took an extra unused otterstat and plugged it in and left it dangling. I then started my car and took a torch and heated the otterstat and the fans kicked on.

So the conclusions I am drawing is there is no flow in the pipe that holds the otterstat, therefore it cannot properly open the fans at the correct time. This would also answer why my engine seems much hotter than normal.

So how do I test if my water pump is doing its thing? It was replaced in 2015 by DMCMW. Or could there be a blockage in a pipe somewhere.

[MrChocky]

At the risk of saying something simplistic, when the engine is cold you can open the overflow tank and watch the coolant being pumped in.

[Jimmyvonviggle]

At the risk of saying something simplistic, when the engine is cold you can open the overflow tank and watch the coolant being pumped in.

If that is a way to do it I will try that.

[Bitsyncmaster]

The otterstat pipe and hose feeding it will get hot quickly when the thermostat opens. That would confirm there is some flow from the pump but not verify normal flow.

[Rich]

At the risk of saying something simplistic, when the engine is cold you can open the overflow tank and watch the coolant being pumped in.

+1 on this tip.

Just pop the rad cap off of the header bottle with the engine cold or at least not very warm. Run the engine and look into the front of the bottle for thin stream of coolant shooting toward the rear of the bottle. That coolant is fed via the small diameter hose connected to the bleeder tee by the heater control valve.

That bleed stream shows the water pump is moving coolant. It does not show you how much flow there is in the main circuit.

As you suspect, if your otterstat isn't always getting hot then the fans won't kick on when they should which leads to

Tip #2:
Be sure the otterstat pipe is oriented with its tee section - and the otterstat - facing DOWN. If it's facing up then the otterstat may not always be in contact with the coolant due to air trapped in the tee. That may create the symptoms you mention.