Dino at Teague Marine told me today that if I wanted to address excessive water pressure I should not plumb into the intake manifold. At this point the entire engine is pressurized and it is much better to relieve the pressure before it enters the engine. Teague sells a tee fitting for the 1 1/2" raw water line with a 1/2" bung fitting and a variety of spring tensions for the relief valve. He stated the same target pressures as have already been cited by Grimes. The reason I didn't pursue this further is because he told me typically water pressure doesn't become a problem until the boat is traveling above 95 mph. I don't go nearly that fast! I'll measure my water pressure this summer before I know if I've got anything to worry about. I didn't ask the price of the Teague unit. Their number is 661-295-7000.

Where are you guys checking the water pressure? I checked mine in the cross over tube, before it goes into the engine, and I am seeing 29 lbs at Wot. I would think if I checked it in the heads or before the thermostat, it would be a little lower. I have the mercruiser "T" on the cross over tube feeding my Gil manifolds. I am running the "T" without the plastic balls, And seeing 28-29 lbs at the cross over. I was thinking the pressure is high there because of the water trying to fit into the 2 water hole's in the block. but after entering there, wouldn't the pressure drop a few pounds because of all the area it has to fill, or keep full?. Should I be checking the pressure somewhere else? I'm hearing that 22 -25 lbs is perfect, but is 29 lbs to much? I usually wouldn't worry to much, but I am running 5-6 lbs of boost.

Kanookstr,
I check the pressure off of the side of the block with a mechanical gauge. 18-24 is the target pressure at wot. The block pressure is what we need to worry about. The coolers and exhaust can take the extra pressure.
Dan

Thanks Dan, I kinda had a feeling I should check it in the block. I will try and relocate the fitting somewhere in the block. I would like to check it in the head. But the Gil manifolds seem to be in the way if the plug that's in the head.

Rex marine sells a nice setup, they recomend putting it on the water line from your outdrive to the pump

Well I moved the gauge into the block, and I see the same 29 lbs of pressure. I'm going to feed my intercooler from the cross over tube like it was. That should drop it down 3-5 lbs, and put me in the low to mid 20's. We'll see this weekend

Ok I finally got the boat in the water. I have over 35 lbs with the stainless marine cross overs with the thermostats in and by-passes. Could only get 130deg.
Took out the thermostats and the pressure drops to 20lbs max. but obviously only about 100deg temp.
I guess i need to reduce the water flow which will reduce the pressure because it cat get out of the the motor because the thermostat never opens.

Mark

Help guys!? I have brand-new rebuild with 30 min of hose time with zero issues and when tested on trailer on ramp pulling its own water up I have llwater in oil alot. Brand-new seaward series manifolds and tails. All new rebuild .Was suspected intake manifold leak and indeed it is I believe I have high water pressure and wasn't seeing it while running on water hose but now on its own it blew intake gaskets. Stock magmpi 502 help me plumb up a relief for pressure ?? ?