Cooking the impeller! Video

Fireman431

Fireman431

Rear Admiral
Joined
Sep 17, 2007
Messages
4,292
Re: Cooking the impeller! Video

Nice. Must be his first boat.

Should this be moved to the loud thru-hull exhaust string? :D
 
A

Aviator5

Chief Petty Officer
Joined
Feb 10, 2009
Messages
431
Re: Cooking the impeller! Video

He probably was showing it to the potential buyer, who was filming.
"boat is in perfect condition - it starts and runs!"
 
D

djsmooth56

Cadet
Joined
Jul 28, 2007
Messages
7
Re: Cooking the impeller! Video

Its possible he removed the impeller before starting it (i've done this a few times when i wanted to check out the engine fix i had completed in the middle of winter). it wont harm the engine if you dont run it for any amount of time. i would be more concerned with the throttle pumping. i've always been told to keep it under 2k RPMs when on the muffs.
 
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bob johnson

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Feb 25, 2009
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Re: Cooking the impeller! Video

Ill reply, because i am not affraid of being honest , and it is real life..

until I found this forum last year, I never worried about starting my boats on the trailer before I put them in the water, or to see if the boat starts before i left home... for YEARS!!!

at least 20 years!! thats four motors!!

I never bought a new motor, all mine were used and from 2001 and earlier.

I had them tuned once in a while, when the motor didnt seem to be acting right...no maintenance, no lower unit oil!!, no winterization, !! no impeller change!!

now i cant remember, but it is possible that one or two of those tunes ups included a LU oil change or and impeller.. dont know

but everytime i got to the ramp, id start my outboard, on the trailer, BEFORE I backed her into the water!! and run for a minute maybe and shut it down

never wanted to unload and then find the boat wouldnt start!!

this was almost always winter time too!!

NOW isubscribe to the "never start with out water to the impeller" theory

only because it makes sense, and i can read about all the problems people have with motors!!


just thought Id add that...


bob
 
ovrrdrive

ovrrdrive

Petty Officer 1st Class
Joined
Apr 28, 2008
Messages
265
Re: Cooking the impeller! Video

This is a little OT, but when we launch our boat the wife gets in before I back into the water. I start backing in and pause when she can get the lower unit in the water, she lowers it in and starts the motor. When I hear it running I back in and slip her off the trailer. When I get parked and get back to the boat, she has it docked and is standing up rods. Teamwork and having a wife not afraid to run the boat pay off. ;)
 
Friscoboater

Friscoboater

Captain
Joined
Jul 3, 2009
Messages
3,095
Re: Cooking the impeller! Video

It usually melts the impeller in its housing. It says in in the owners manual all over the place not to do so. Marine shops make good money of guys like that.
 
The_Kid

The_Kid

Chief Petty Officer
Joined
Apr 18, 2008
Messages
447
Re: Cooking the impeller! Video

bob johnson said:
until I found this forum last year, I never worried about starting my boats on the trailer before I put them in the water, or to see if the boat starts before i left home... for YEARS!!!
Click to expand...

I bought my 1990 Evinrude new, and have fired it up dry, every year prior to putting it in the water for the season, and I haven't ruined any impellers. Then again I don't run it like the guy in the video. As soon as I hear it fire and I know it's going to start when it's in the water it's shut off.

We're talking about running for less than a second. Figuring maybe a 1000 RPM when it first fires, the impeller is only going to make about 16 revolutions. I change the impeller every 3 to 4 years and none of the old ones have shown any abnormal wear.
 
Friscoboater

Friscoboater

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Joined
Jul 3, 2009
Messages
3,095
Re: Cooking the impeller! Video

I wonder is O/B impellers are different. I remember my Grandfather starting his O/B motor all the time without water, but when it came the the I/O we had he was OCD about having it in the water. It says in the Merc manual to change the impeller every season for the Alpha Drive.
 
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bob johnson

Rear Admiral
Joined
Feb 25, 2009
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Re: Cooking the impeller! Video

friscoboater said:
I wonder is O/B impellers are different. I remember my Grandfather starting his O/B motor all the time without water, but when it came the the I/O we had he was OCD about having it in the water. It says in the Merc manual to change the impeller every season for the Alpha Drive.
Click to expand...

well seems to make some sense, as a lot of inboards are V8's and create a lot of heat and need good cooling.....lots more volume of water needed, there is a lot of mass in a cast iron V8 4 stroke motor!!!!

little info....

I damaged the prop shaft on my motor, but i have a similar model as a parts motor. so i took the LU off the parts motor and decided to install a new water pump..

there is an O-ring seal where the plastic housing meets the SS plate!!...means they want to seal off the water,, maybe to keep pressure up...

well i couldnt bolt my housing down enough to not be able to see air between the housing and the plate!!!!!!!!!!!!!!

told myself...ah -oh... not good.. so I applied a lot of form a gasket material and figured id watch the water pressure and if it wasnt at least what the previous LU was giving me, Id redo the job...

well when i took the bad LU off, which was giving me 30psi at WOT and 10 at idle....low and behold there was a gap under that water pumps housing!!!!!

I know it isnt supposed to be there..but it was, and it still pumped enough water.....

leading me to believe that the water pump can pump way more water than is really needed on a 2 stroke motor....maybe ha ha ha
 
Philster

Philster

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Joined
Sep 15, 2009
Messages
3,344
Re: Cooking the impeller! Video

djsmooth56 said:
Its possible he removed the impeller before starting it (i've done this a few times when i wanted to check out the engine fix i had completed in the middle of winter). it wont harm the engine if you dont run it for any amount of time. i would be more concerned with the throttle pumping. i've always been told to keep it under 2k RPMs when on the muffs.
Click to expand...

Throttle pumping doesn't matter in this case, because he doesn't have water flowing to the engine. If you hook up a hose/muffs, then you got just enough water flow for idle, give or take a couple of hundred RPM. So, you don't rev it up on the muffs, because you can cook the impeller.
 
redone4x4

redone4x4

Lieutenant Commander
Joined
Feb 28, 2009
Messages
1,548
Re: Cooking the impeller! Video

that sucks, Liberators are awesome boats too. I run mine on the muffs every time the day before we head out. I will occassionally run it up to 2k rpms and then back down. I have even held it at about 1000-1200 just to get everything moving and charged up and it has been fine. It has never, ever even reached operating temp while sitting on the trailer.
 
QC

QC

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Joined
Mar 22, 2005
Messages
22,783
Re: Cooking the impeller! Video

Who gives a ship about his impeller? That flippin' thing has a hydrofoil on it :eek: Ewwwwwwwww . . .

Maybe he packed a bunch of snow in there? Maybe . . . :rolleyes:
 
redone4x4

redone4x4

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Feb 28, 2009
Messages
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Re: Cooking the impeller! Video

QC said:
Who gives a ship about his impeller? That flippin' thing has a hydrofoil on it :eek: Ewwwwwwwww . . .

Maybe he packed a bunch of snow in there? Maybe . . . :rolleyes:
Click to expand...

haha I was wondering if maybe it was "humid" enough since it was so close to the snow on the ground:D
 
Friscoboater

Friscoboater

Captain
Joined
Jul 3, 2009
Messages
3,095
Re: Cooking the impeller! Video

Yeah, his channel is funny.

As for the impeller. it is not the heat of the engine that you worry about. It is the friction the impeller makes inside of its housing that melts it.
 
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