sre

Where is the best place to install a water pressure relief valve on a HP 500 with a crossover. Before or after the raw water pump?

Thanks

BY U BOY

After The Raw Water Pump Before The Oil Cooler.

rv

Why would you want to dump the water before a cooler. Seems like you want to take advantage of all of the water coming in to cool everything possible. As long as you can successfully relieve the pressure in the block below its maximum, put it as far down stream as possible. That way you get the most water flow helping with cooling.

Rick

klaw

I put mine right before my crossover and the ran the hose straight over the engine and out the transom

Raceangel77

Hi;
The best place to put the pressure relief valve is of the strainer before the pump. Think of the relief as a fuse. You want to relieve the pressure befor it hits the system.
The biggest damage is not done when running but when comming off plane at speed. With the impeller and engine trying to slow down the water pressure and flow is working against the impeller. This causes what we call harmonic back lash. The best case is that it damages the impeller and the worst we have seen is a collapsed pulley wheel.(not On our Pump , but to be honest we had some extreme conditions that wore the keyway badly.) Now designed out.
The trend with high performance boats is to put in big water pickups and this can make the situation worse. It does not matter whose pump you are running a pressure relief valve will save a great deal of stress to the water system and the engine.

the other advantage of putting the relief valve on the strainer is that it does have the benefit of ejecting any sand build up that may occur if you have a sand strainer.
Hope this makes sense.

PS our relief valve are designed to pass sand without damaging the seal.
Jules

rbtnt

If you put the relief valve before the pump, don't you take a chance of sucking air if the relief is stuck open by something like sand?

sre

Thanks for all the replies!