Merc Water Pressure
 

What is max pressure that could be seen for or a standard Merc belt driven pump for open cooled system, and measured at the block?

When I installed a imco lower unit mine went to 35lbs. Had to install a pressure regulator. Cruse it now runs about 14 and wide open about 22lbs.

PCM and ECM 555 STOCK rating is 30 psi MAX. And one has to use the correct sensor and the newest rated sensor plus all adapted has to be completely grounded that the sensor mounts into.

Thanks was looking at a VDO 30 and 40 PSI gauge

Will be installing mechanical gauge from block to helm

Merc is 50 psi not the 100 psi anymore that they recommended. It caused issues. Look for the post I did up here about RFI and the water pressure sensor. I think it was from the guy doing an aftermarket combo oil cooler.

Merc 40 psi sensor or an aftermarket 40 psi caused issues - Just had that discussion in Person last week.

All great info as always but my ECM doesn't have any connection to a water pressure sensor, Just wondering which gauge to use for see how the impeller in the pump is doing

I just switched over to imcos and was concerned about this because of what I Hurd. But some friends told me I would be ok. I was running the dull water pickup lowers befor. What speeds where you running that was giving you the problems? We talking 55 to 80 or over 80. Thanks

50 to over 80

Was it actually the standard Merc single stage pump?

I swapped sportmaster for imco lowers on a 39 o/l. Pressure went from just touching 30 to wrapping the gauge back around to 0. Got it down to 38 for the key west run. This was a 525 boat. The 41 with 700's had a cooling issue and merc service manual said min 30psi @ wot

I have an Imco shorty and a Mercury pressure regulator.

It dumps water at idle and runs around 30-32 PSI running.

I would love to drop the pressure to about 20 or less.

Ken

i have the same on my Playboy boat. Valves that keep it while running at below 30. I only idle around 10. Merc 500 EFIs that make 625+HP

It is a Jabsco brass single stage pump.

Thanks

I first tried one of those regulators and had the same problem .Then I got a weaker spring and the pressure fluctuated real bad. So I ordered a regulator from CP that is adjustable problem solved.

My info was from OEM stock black side ecm 555 and pcm 555 as really thinking the op set up but was not sure what he has nor a stock set up nor what ECM / PCM

Water pressure psi ------- Correct the 700 Sci as Merc spec is 30 psi min at 5200 and MAX 50 psi at 5200 and will add this info the 600 SCi early engine serial numbers were that same as the 700 SCi but later engine serial numbers for the 600 SCi was 30 psi min at 5200 and MAX 42 psi at 5200 --- Merc Spec

Thanks

Ken