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NoMoreBeggin MC
07-11-2009, 11:03 PM
I have seen a few guys pull their boats out of the water, stop once the boat is no longer pulling water in, and rev the engine to blow any excess water out of the exhaust manifolds. Is this something I should do with my 82 stars and stripes? Are they doing it for some other reason?
thanks

justinglow
07-11-2009, 11:20 PM
I've only seen people on PWC's do that.

TMCNo1
07-11-2009, 11:35 PM
That would be the best way to destroy a raw water pump impeller, I would not recommend doing it.

Eagle Lake Rebel
07-11-2009, 11:35 PM
Very bad idea, you should never run your raw water impeller dry. As far as following the lead of what jet skiers do just watch them for a weekend and you will see that the bulk of them have no idea how to operate a vessel in or out of the water. That being said I own a Jet Ski too, but never operate it without a water supply and I never junmp the wake of other boats.

JimN
07-11-2009, 11:36 PM
I have seen a few guys pull their boats out of the water, stop once the boat is no longer pulling water in, and rev the engine to blow any excess water out of the exhaust manifolds. Is this something I should do with my 82 stars and stripes? Are they doing it for some other reason?
thanks

Does it seem like they're trying to impress people? If so, that should answer the question. It also means the raw water system is dry, which means it will take a little longer to draw water in when they start it again.

Other than maybe trying to eliminate zebra mussels so they think it's safe to take it to another body of water, I can't think of a good reason for this. Have you though of asking them about it?

Footin
07-11-2009, 11:48 PM
I've only seen people on PWC's do that.

I always wondered why they do that, I think they are trying to look cool reving up their engines. I know it impresses the heck out of me!

babymoore3
07-12-2009, 11:17 AM
Agree with all above, not to mention that you will heat soak the engine (cause high temps and then shut down). This stresses all the gasketed joints in the engine. Can be problematic if you have aluminum heads/ intake and iron block!

mtajpa
07-12-2009, 07:58 PM
That would be the best way to destroy a raw water pump impeller, I would not recommend doing it.

Actually that is the 2nd best way to destroy raw water pup impeller. 1st way was when he started it up on the trailer while backing into the water.

TX.X-30 fan
07-12-2009, 08:08 PM
That would be the best way to destroy a raw water pump impeller, I would not recommend doing it.



Up-side would be he could peruse the thousands of "how to change an impeller" threads. :D

TMCNo1
07-12-2009, 08:22 PM
Up-side would be he could peruse the thousands of "how to change an impeller" threads. :D

Is that called multi-tasking?:rolleyes:

boyd
07-12-2009, 08:49 PM
FYI. All jet ski manufacturers reccommend starting the engine out of water and running for 7-10 seconds and revving the motor 2-3 times. Something about blowing the water out of the waterbox. This should be done while the front of the jetski is higher than the back.
This is why they do it on the boat ramp.

BOYD

Proud owner of 1992 205, 1995 Kawasaki, 1999 Sea Doo.

Thrall
07-13-2009, 01:10 PM
FWIW, I usually start the engine once after it's out of the water, for all of 2-3 sec. Even that leaves a little water in the manifolds. I don't rev the engine though, it spits out the water almost instantly. Haven't fried an impeller in 6 yrs. And I wouldn't do it if the boat jsut came off a hard pull, but mine usually idles around for a while before getting loaded up.
With all the rust and scale that comes out of the manifolds each fall, I try to keep the engine as dry as possible between uses.

captain planet
07-13-2009, 01:16 PM
I think this is the equivalent to the guys with the Harley's that rev up their bikes every 4 or 5 seconds when they pull into a parking lot or are sitting at a light. :noface:

Kingsley X-1
07-13-2009, 02:54 PM
I think this is the equivalent to the guys with the Harley's that rev up their bikes every 4 or 5 seconds when they pull into a parking lot or are sitting at a light. :noface:

you took the words right off of my keyboard... :uglyhamme

JimN
07-13-2009, 02:59 PM
Are these the same guys with the "Loud pipes save lives" bumper sticker on their Honda car?

TX.X-30 fan
07-13-2009, 03:47 PM
I think this is the equivalent to the guys with the Harley's that rev up their bikes every 4 or 5 seconds when they pull into a parking lot or are sitting at a light. :noface:




Hell whats wrong with that I put my window down just for the sound and maybe a sent of burnt fuel. :D

east tx skier
07-13-2009, 03:54 PM
FWIW, I usually start the engine once after it's out of the water, for all of 2-3 sec. Even that leaves a little water in the manifolds. I don't rev the engine though, it spits out the water almost instantly. Haven't fried an impeller in 6 yrs. And I wouldn't do it if the boat jsut came off a hard pull, but mine usually idles around for a while before getting loaded up.
With all the rust and scale that comes out of the manifolds each fall, I try to keep the engine as dry as possible between uses.

Is a boat more likely to corrode with less water in the manifolds? Short of flushing with rv antifreeze every time, I can't imagine it would make too much of a difference on a fresh water boat. Air and moisture strike me as being a worse combination than leaving the manifolds full of water.

I'll profess that I am no expert on the subject. Just expressing my curiosity.

TMCNo1
07-13-2009, 04:09 PM
I've been known to be walking up the ramp to get the van and about half way up, cut wind and burped at the same time and people will look to see what kind of jet ski it was, does that count?:rolleyes::D

aremsing
07-13-2009, 04:38 PM
Now that's funny

JimN
07-13-2009, 07:54 PM
I've been known to be walking up the ramp to get the van and about half way up, cut wind and burped at the same time and people will look to see what kind of jet ski it was, does that count?:rolleyes::D

Depends- does it sound like a jet ski that hit the rev limiter?

TMCNo1
07-13-2009, 07:58 PM
Depends- does it sound like a jet ski that hit the rev limiter?

That made my day!
I can hear it now, no wait, I mean mentally!:rolleyes::D

Thrall
07-13-2009, 08:15 PM
Is a boat more likely to corrode with less water in the manifolds? Short of flushing with rv antifreeze every time, I can't imagine it would make too much of a difference on a fresh water boat. Air and moisture strike me as being a worse combination than leaving the manifolds full of water.

I'll profess that I am no expert on the subject. Just expressing my curiosity.

Yeah, you're probably right, no exposure to air = no corrosion.....I dunno it probably doesn't matter, but it hasn't burned up my impeller doing it either.

Trent 197
07-13-2009, 09:30 PM
I agree that this is probably not a good idea...but I'm not sure how running the raw water pump dry could ruin the impeller? Cavitation? The impeller is rubber (or plastic) and probably cavitates every time you suck new water. Temperature? It's shaft driven.

Can anyone elaborate??

JimN
07-13-2009, 09:36 PM
I agree that this is probably not a good idea...but I'm not sure how running the raw water pump dry could ruin the impeller? Cavitation? The impeller is rubber (or plastic) and probably cavitates every time you suck new water. Temperature? It's shaft driven.

Can anyone elaborate??

Friction. When the raw water pump runs dry, the rubber against the brass generates a helluva lot of heat, which takes out the gasket and vanes. In some cases, the rubber lets go of the hub abd the next time it runs, the hub spins but the rest of the impeller just sits there. I melted the fingerprint on my index finger when I accidentally touched a pump housing that had run dry. I don't recommend that.

Ubugme2
07-13-2009, 09:37 PM
The impeller spins vary fast inside that housing and the impeller is Lubercated in a way when the water is pumping from the lake. When there is no water it will eat the tips of the impeller right off in a matter of seconds if it is dry and spit them into your cooling system, and that makes it a little hard to find all the little rubber chuncks. I have seen them all the way up at the thermostat in my friends boat.

H20BOY
07-13-2009, 09:40 PM
In regards to running a PWC out of the water, I was told it was to burn the fuel out of the carb after you sut off the fuel. I was younger when I had a Jet Ski and the real reason was just to rev up the engine.

mbpd312
07-13-2009, 09:47 PM
jet skier do it to empty their waterboxes. Its done so water does just sit there while the jet ski is stored until next use. Settle down fellas, its not just these guys showing off, its for a purpose.

TX.X-30 fan
07-14-2009, 10:34 AM
But a couple of revs does it. I never did that at the lake waited till I flushed at home and did it.

hkallestad
07-14-2009, 11:00 AM
I would say that it takes a little more than seconds before the impeller melts, maybee if its completely dry it would melt right away.

When I ran my boat for the first time this season the pump didnt suck any water, and after a while engine temp went high and the impeller was squeeking, but impeller looked fine afterwards. So engine temp would be more of an issue than the impeller itself since the tiny water amount in the impeller would probably lubricate it for a short while.

Trent 197
07-14-2009, 02:09 PM
Friction. When the raw water pump runs dry, the rubber against the brass generates a helluva lot of heat, which takes out the gasket and vanes. In some cases, the rubber lets go of the hub abd the next time it runs, the hub spins but the rest of the impeller just sits there. I melted the fingerprint on my index finger when I accidentally touched a pump housing that had run dry. I don't recommend that.


OK, heat removal makes sense. Thanks.

ROB
07-14-2009, 06:29 PM
It doesn't take much to mess up your impeller. I like to flush at home on the fake a lake. My brother has a SeaRay and does the old five second engine rev when he pulls off the lake. Doesn't make sense to me.