I thought this was a bad Idea...

[seabob4]

Re: I thought this was a bad Idea...

The last impeller replacement I did was on a customers mid-90s Merc 225 ProMax, god knows when it was last changed. I had to chisel the damn thing off...

 

[superbenk]

Re: I thought this was a bad Idea...

They do make a higher silicone content impeller which the manufacturer says it OK to run for up to 15 minutes out of water. I'm sure these guys are not all equpiied with them, just an FYI.

http://www.globecomposite.com/pages/products_impeller

This is kind of interesting. I looked at their site, but didn't really see if they offer one for the old Stringer 400's?

 

['78 Crusader]

Re: I thought this was a bad Idea...

I replace mine every 100 hours, without fail. It's strange, though. I have pulled out impellers with 100 hours on them and they look great (they become emergency spares) and I have pulled ones out with 100 hours and they look like crap, with vanes about to fall off. Same water, strainers working and clean, same temps. I guess there's no common denominator. To me, it's cheap insurance.

Same here, can't explain why. I do the same thing each weekend on the same lake for the past several years....

I guess the impellors that crap out early are the one's made in China and the ones that last are made here in the Good 'ole USA....

 

[Daver29]

Re: I thought this was a bad Idea...

OK, Not to keep this thread alive for ever!!! but it does beg the question. Why don't they build a better impeller, or a better pump all together so that its not such a maintenance issue. The rest of the I/O is basically like the rear end or transfer case in the car... change out the fluids regularly and you should never have to open it! So why not make the pump/impeller more durable or easier to maintain!?

Does the water do any cooling/lubricating (other than the impeller) in the I/O itself?

 

[superbenk]

Re: I thought this was a bad Idea...

OK, Not to keep this thread alive for ever!!! but it does beg the question. Why don't they build a better impeller, or a better pump all together so that its not such a maintenance issue. The rest of the I/O is basically like the rear end or transfer case in the car... change out the fluids regularly and you should never have to open it! So why not make the pump/impeller more durable or easier to maintain!?

Does the water do any cooling/lubricating (other than the impeller) in the I/O itself?

Seems like that's what Volvo does by putting the pump on the alternator belt off the engine itself. Not sure why that's not more common. I know for sure changing it in a Stringer is a major PITA.

 

[Knot Waiting]

Re: I thought this was a bad Idea...

They do make a higher silicone content impeller which the manufacturer says it OK to run for up to 15 minutes out of water. I'm sure these guys are not all equpiied with them, just an FYI.

http://www.globecomposite.com/pages/products_impeller

Very interesting find. Although what sort of market exists for this type of product in the marine envrionment? I mean, who has the desire to run dry in the first place... much less for up to 15 minutes (can you say overheating?).

 

[superbenk]

Re: I thought this was a bad Idea...

Very interesting find. Although what sort of market exists for this type of product in the marine envrionment? I mean, who has the desire to run dry in the first place... much less for up to 15 minutes (can you say overheating?).

I'd love to be able to start up without hooking up a hose for short periods occasionally. For instance, I tend to start the boat at home prior to going to the lake just to make sure everything is in working condition. It's a pain to hook up the hose & then unhook it.

 

[Home Cookin']

Re: I thought this was a bad Idea...

Very interesting find. Although what sort of market exists for this type of product in the marine envrionment? I mean, who has the desire to run dry in the first place... much less for up to 15 minutes (can you say overheating?).

it would be nice to know you can start in any conditions and not worry about it (after all, it's dry until it pumps water in, right? Or are they all below the waterline?) and it stands to reason it will last longer.

 

[seabob4]

Re: I thought this was a bad Idea...

FWIW, my Suzuki guy, Eastern US Field Applications Engineer, has told me that you can start up a Suzuki for a very brief period, say 30 seconds or so, without damage to the impeller. And I have seen him do it many, many times. He has never told me whether Zuke uses a different type of material for their impellers (I'm sure they buy them from somebody), but I would think they are no different than any other modern O/B...

 

[superbenk]

Re: I thought this was a bad Idea...

it would be nice to know you can start in any conditions and not worry about it (after all, it's dry until it pumps water in, right? Or are they all below the waterline?) and it stands to reason it will last longer.

If they're on a hose, there's water pressure involved pushing water up into the impeller housing before you start up. If they're below the waterline, then they're already wet.

 

[Knot Waiting]

Re: I thought this was a bad Idea...

Ok, I can see the added peace of mind just knowing you're not gonna smoke the impeller in 15 seconds.

 

[2000fourwinns]

Re: I thought this was a bad Idea...

I know people who "bump" their engines either at home or the staging area to be sure the starter hits. I have though about doing that, but there is a good point about bumping the engine with the outdrive all the way up. Even a few degrees rotation on the u-joints in that kind of angle can't be good. Am I wrong?

 

[mgmidget72]

Re: I thought this was a bad Idea...

I know people who "bump" their engines either at home or the staging area to be sure the starter hits. I have though about doing that, but there is a good point about bumping the engine with the outdrive all the way up. Even a few degrees rotation on the u-joints in that kind of angle can't be good. Am I wrong?

Wouldn't you be in neutral when you bump the starter?

 

[superbenk]

Re: I thought this was a bad Idea...

Wouldn't you be in neutral when you bump the starter?

Doesn't matter. Shifting happens inside the leg, not before the U-joints. When the motors turning, the U-joints are turning - always.

 

[mgmidget72]

Re: I thought this was a bad Idea...

Whoops, thanks for clearing that up.

 

[Hashi]

Re: I thought this was a bad Idea...

Just wondering, I'm fairly new to boating and only have about 40 hours on my boat. I know you have to replace the impeller regularly but how difficult is it to replace them? Can this be done as a DIY project?

 

[sw33ttooth]

Re: I thought this was a bad Idea...

Doesn't matter. Shifting happens inside the leg, not before the U-joints. When the motors turning, the U-joints are turning - always.

well thanks for that little piece of info, i figured as long as it was in nuetral and idleing i was good.

as for impellor, i must say i am bad i have started my motor a few times without water on it and for longer then just 2 seconds. i winterized my boat by taking the hose off the engine and pouring antifreeze in it running impellor dry for 5 minuites or so. i just replaced the impellor about 2 weeks ago, and it looked perfect i probably had 20 minuites tottal run time with out a water hose on it and 30 hours. i did notice that water came out of the impellor housing when i took off the 3 bolts so it wasnt dry. another thing to look at is exhust risers those get very hot very fast with out water.

thank you god for making it so easy to replace the impellor on a 91 cobra outdrive took 2 minuites.

 

[sw33ttooth]

Re: I thought this was a bad Idea...

Just wondering, I'm fairly new to boating and only have about 40 hours on my boat. I know you have to replace the impeller regularly but how difficult is it to replace them? Can this be done as a DIY project?

depends on the motor, my dad has a kicker ob motor you take the engine out and the lower unit off to change it takes 2-3 hours. i had a johnson v-4 90 hp that took me 2 hours to do drop lower unit and take out the shifter screw. on my newest boat omc cobra outdrive i did it in 2-3 minuites on my first time.

 

[oldjeep]

Re: I thought this was a bad Idea...

YUp, really depends on the drive. OMC cobra you can do in 10 minutes with one wrench, mercruiser takes a bit longer since you have to remove the lower unit to do it.

 

[2000fourwinns]

Re: I thought this was a bad Idea...

What is the norm around here? Do you lower the foot before "bumping" the engine? Do you not let the boat off the trailer before bumping? Or do like I do and slide the boat off the trailer into the middle of the lake, then see if the starter works? haha.