Poppit opening or not??

[andy6374]

Temp gauge reads normal and alarm isn't going off.

Water pressure is 5-7psi at idle and at WOT it is about 18-20 psi. Is the 18-20psi to high? I just read a post by gss036 and he said his manual (1989 200hp) states that the water pressure is around 12 psi at WOT. Mine is an 1988 I doubt it would be different. The hose that runs from the gauge is "T" into the hose that comes from the top of the block (behind the flywheel) and runs the side of the poppit valve housing cover. This I beleive is to rid the system of air bubbles.

Water is pouring out of the relief ports in the rear of the motor (just below the cowling) at higher RPMs? Is this normal? Every component of the poppit assembly is new,, the only reason the poppit wouldn't open (i not saying it isn't opening either) is if the spring was too stiff. But I'd figure that 20 psi would push it right open.

 

[andy6374]

Re: Poppit opening or not??

^bump

 

[Laddies]

Re: Poppit opening or not??

Andy, thats a little high, your right 12# is about right. I guess you might change the spring and diaphram on the valve but as long as the engine is cooling what does it hurt--Bob

 

[gss036]

Re: Poppit opening or not??

Andy, I think there is a high pressure pump available, but don't have any idea which motor applications take. I have read several post where engines are showing pressures such as yours.
The info your read is exacly what is in my OEM manual for my 1989 200 hp motor. It lists water pressure @ 12psi minimum 5500 RPM , it does say minimum, higher pressure may very well be acceptable. My manual covers 1989-1990 Models 200/200XRi w/sr# 0C100861-0C291519. It also covers 1989 135-175 hp motors.
The exhaust ports at the top rear of the leg are designed to exhaust excess water/exhaust.

 

[andy6374]

Re: Poppit opening or not??

My merc factory manual makes no mention of minimum water psi. Perhaps they give the minimum so you know when the waterpump needs replacement. I don't think I have the high pressure waterpump kit as I bought the kit for my motor via the serial number.

WHen the poppit opens I know it dumps excess water out the exhaust...but does the routing go to the exhaust thru the prop or thru the relief ports? If it's thru the relief ports, then I am not worried at all because that's what I am seeing.

I can tell when the tstats open at idle speeds because you can watch the psi's go up and down with weaker and stronger tell-tales (ie closing and opening of tstats). What I need to do is slowly increase the RPMs...watch the psi's increase and look for a sudden decrease in water psi's which would tell me that the poppit is opening. I doubt there is anything wrong because all the components are new and the temp gauge reads fine and no overheat alarms...but just making sure. here

 

[gss036]

Re: Poppit opening or not??

Andy, I think you are ok w/what you have. In your Mercury manual, look under sec 1, page 2, General Specs, very bottom will maybe list the water pressure.

 

[andy6374]

Re: Poppit opening or not??

Wanted to post an update:

Now that the I've put 30+ hours on the new impeller, the water pressure values are closer to spec. At 5500 RPMs I'm getting 15 psi and at cruising speeds it's 10-13 psi. So my guess is that the new impeller just needed to get broken in a bit.