Bobs Nosecone....Low Water pressure..WHY??

[jimydgreek]

Just had my new Bobs nose cone installed (factory installed), and Ive noticed that the water pressure is between 3-5 psi at idle and up to about 2000 rpm. But when I am running it above that, 2000 psi and above, my water pressure is "almost disappearing to "0". However the motor is still "pissing" out the water outlet, but not full force like it is at 3-5 psi "idling". Temp remains good throughout. i really dont want to blow the motor. Im confused. Any ideas? Please help. Thanks Jimmy:confused:

[INXS]

I think it's only reading when you need flow to the block? If I recall it jumps up to something like 16 psi when I'm on plane. I can't recall as I haven't been out yet this year but I do remember asking the same question last year.

[bw1969]

The rubber hose may be collapsing when the water pump starts sucking, or you may have some debris floating around in your block. Sounds like you might be heading towards a larger problem. Are you sure you are not sucking air through the LWP once the hull is on plane?

[Narcoholic]

First what kind of motor is it???

[jimydgreek]

Its a Merc 150 hp..... all appears fine w/ motor. I "may" be sucking air but I dont know how I would be....I have a hydrodynamics jack plate and it is still all the way down. (id say at least 4" underwater----bottom of boatside). I ve checked the entire line to make sure its not kinked or whatnot. Im just lost now. Scared to death cause I dont want to blow it ya know! If the temp is good throughout, does that mean Im getting "sufficient" water flow? anyone???

[whipper]

Drop your gear case,pull your T-Stats and back flush with a hose. May as well do the impeller while your at it. Another thing you can do is get a laser heat beam gun or what ever there called and when your temps say good shoot your block with the beam and get a true reading. Your water pressure low usually meens drop the gear case and your motor not hot could be because the water temps are still cool and your not loading her up to much and even with the bit your getting still keeps things alright for now. It could be a combination blockage or impeller plus the temp guage not reading correctly. It wouldnt hurt to just drop and flush and put a new impeller in. Then atleast those bases are covered. James