Tying water pressure relief into bilge pump
 

Tried searching to no avail. I am going to add a pressure relief valve. I plan to tee into the 1 1/4" pump out line before the coolers and crossover. Was planning on doing this after the coolers but if I relief at 20-25psi that still should be plenty going thru the coolers as I only see 140-155 oil temps as it is. Anyway, to keep simple and holes to a minimum, I plan to Y into the 3/4 bilge pump outlet hose in leiu of a new dump location. I will install a one way check valve on the relief line before the Y and also the bilge line before the Y. Anybody see any problem here? Only problem I see is obviously if I were to run the bilge pump at 80 plus mph while the relief may be open. Also, when typically do you need to use the 3/4 relief valve over the 1/2? Oh, and reason for this is I am running a crossover, water stat, and now an imco shorty and want the safety to relieve pressure. I appreciate your help.

You are making this way to complicated. Mine dump when the boat is at idle. It would be a little hard to run the bilge and relief at the same time. I have mine as close to the engine intake as possible.
Yes this topic has been covered in the past.

I may be over thinking yet if someone has done this and its proven to work it would literally be a 5 min install. I have a coupler on the 1 1/4" line right behind the motor 6" away from my bilge discharge line. Take off coupler, install tee, install y and 2 check valves, tighten clamps. No holes, no 6' of tubing to dump, ect....as long as I am not running 20 plus psi at idle as bigjim is seeing it almost seems to simple.....just figured I'd run it by and see if it was literally a no brainer to try or a definite no no. Thanks

If I were going to do what you are talking about I would put in two checks. One on each side of the "T" you use to cut in your line. Basically you are looking to prevent water passage from one device (ie cooler or bilge pump) to the other.
Installing a dump would be the preferred method though.

I just put a water pressure guage in and took the boat out today. Running about 35 PSI, so need to bleed off about 10 PSI. I plan on running a relieve valve off of the intake manifold and tapping into the bilge hose for discharge. Got to figure out some check valves as well.

Correct, thats exactly how I had figured. One on each side of the Y (one from bilge pump, one from relief) before the Y enters the discharge line.

Now, what is the rule on 1/2" or 3/4" relief? I'm guessing I can just install the 3/4" relief valve due to the fact I already have a 3/4" line I will be discharging thru, correct? I'm guessing guys bump up from 1/2" to 3/4" when they are not seeing enough drop in pressure. Just wondering what size most of you are using and what pressure drops you noticed. Thanks
Chris

I'm wondering if a bilge pump makes enough pressure to open a check valve. It seems easier to me to just drill another hole in the boat and install a dedicated fitting.

Just my .02 here, I have been down this road and have sucessfully made this work. Scratch all your ideas and add a bypass with a new dump in the side of the boat and be done.... trust me. I ordered lighter springs from Mcmaster Carr at another members recemendation and they aslo dump just off idle. Spring p/n or ID Code as package says :
P6-C080S60SQ128 http://www.mcmaster.com/# .
Mine now run at about 20psi near 100mph with -2 Imcos on a Scarab flat bottom. Good Luck

I was planning on running a 1/2" hose from my intake manifold to my adjustable relief valve, then run 3/4" hose out. After every ones suggestions, I am going to just put in a new dump.

Like Elimated 572, I am wondering if the 1/2" line is going to be too restrictive? What are everyones thoughts on this?