8.1 Raw h2o pumps-Long
 

FYI - FOR YOU GUYS WITH THE 8.1L

pulled the boat out of storage and, as I've done a 100 times on my other boats, fired up the motors on the hose. After 90-120 seconds or so, port engine began flowing water but didn't get squat from the port tip.
Starboard engine didn't get anything, so I shut it down.

Boat was scheduled to go in for the last recall notice anyway, so I pulled one of the pumps, convinced I fried the impeller. The impeller looked fine but the face wear plate was "gawled" (sp) 1/16" deep. Dropped the boat off at the dealer and showed the tech the pump I'd removed.

Thought maybe the silt, etc. where I boat had caused the damage, and was surprised when he exclaimed "no way". I got two complete pump assemblies all covered under warranty. The tech is convinced these pumps will eventually be redesigned. After the new pumps were installed the tech informed me that he also, did not like the water flow on his hose and took the boat over to the ramp to run them up to temp. He was thinking that the 50-60 psi that we have here in potable water, is not enough to feed these motors (more volume/pressure required because of the closed cooling). These pumps are a new design and are not interchangeable with any previous merc. units.

ps. The labbed Yorks are the ticket. I picked-up 200 rpm w/130 gallons onboard and 3 people.

I had the exact same problem (brand new boat, maybe 7 hours) w/ my pumps too. Had the tech look at them, and he thought it was odd that BOTH pumps died. So he hooked up a hose, started the motors, and instead of leting them run at idle, he gave it some gas to about 2K. Water started flowing just fine. Tech "thought" the pump lost suction due to the boat having sea strainers.
Now everytime I start the boat, I slowly increase throttle (after oil preas. builds) for about 5 to 10 seconds. Never had a problem since.

York props gave me about 250 RPM. Best GPS speed is 79 almost 80 MPH. Can't break out to tenths due to analog speedo dial. But those edges are SHARP!!!! I touched one VERY lightly and sliced my finger!!!! There is NO WAY I'll board the boat from the ladder with those props mounted.

Kentz:
What is your best speed??????
At what amount of trim?

Throttling it up makes a lot of sense. I typically would not do it in the driveway. What's the moral to the story? don't start-em out of the water:eek:

Bill, there is a ton of debris (heard two distress calls of hitting submerged object, taking on water) here, so I was only on it for about 90 seconds, saw 4900 in no time. Did not have my Garmin with me, but my pitot tube Gaffrig (which is amazingly always within 2-3 mph) pulled right to 80. I'll check it next week for sure, that was my first outing and I had just filled it earlier to get rid of the STABIL I had in it. Water was relatively flat and I'm sure I was at 5/6 on trim.

I would think ALL labbed blades are sharp. Did have a little more blow-out coming on plane than the stockers.

I start mine on the hose all the time, I just use the starting procedure above.

I get my best speed (so far) at trim level at 3.75 to 4.

Bill

I am the same with the hose start-up procedure and have had no problems yet...

At 4950 RPM and no labbed props (standard 28P Bravo's) I got 80.5 MPH with my 496 HO set-up. I would like to get them labbed so that I can pick up and extra 200 RPM and hopefully a mile or two on the speed.

I too have had no problems with running on the hose. However, the water will run out of the low water pick up until the rpm's are increased above 1000. Then the flow down and out will stop and water starts flowing up into the engine. Kentz, do your drives have a low water pick up?

Bill, how will you get back into your boat after swimming if you are not going to use the swim ladder? ;)

Macklin

Mac, I'm glad you asked. . . . . I'll use YOUR ladder?!
or Jr's.

for now.

wms - I have both the standard and low (tape low closed). I only let it run at idle 650rpm. I think Bill is right, getting it above 1200-1500 should do the trick.

vyper - don't forget salt h20 adds 2-3mph!;) rev limiter is 5050:eek:

Isn't that the truth. We ran up the James River on Saturday and you could actually watch the speedo go down by 2 - 3 mph when we started getting into fresh water. Felt like the boat was getting sucked down onto the water. The only advantage of salt water.

Kentz, let us know if the idling up while flushing does the trick for you.