Merc 8.1 Horizon Owners: Impeller replacement schedule???

[ziekman@cox.net]

I was wondering if any 8.1 horizon owners could comment on

1) Your impeller replacement "history", ie at what hours/ time intervals have you replaced your impellers?

2) Have you ever had to replace, due to breakdown or were your replacements all preventive? If you did replace, due to breakdown, what was the interval from the last time they were replaced?

Thanks everyone!!!

 

[skolbe]

3 years is what I follow as preventive maintenance. I watch the water pressure gauge on smartcraft. It slowly drops. At the end of the 3rd year - I had 1 fin partially missing.

 

[hack4alivin]

I concur with every three years. I did mine two seasons ago so next year will be time to do it again, as a PM issue. Of course there was once someone on the forum here that was a proponent of the “wait till it breaks” theory…… but that’s not me.

 

[Dasch Boat]

I replaced mine last spring, one year after I purchased the boat. The bolts appeared to be untouched so I'm thinking the impellers were the original units with about 375 hours on them. Still intact but with a definite set to them. I will keep to a 300 hr or 3 year schedule from now on.

 

[sbw1]

The answer is heavily dependent on where and how you boat. As noted above, Great Lake boaters can go a long time. Mine were replaced last fall, these on motors that had just finished 7 seasons. The new impellers out of the box looked just like the ones we removed. The old ones had gone 4 seasons. Not Mercs but I'd bet the results would have been similar. Our boat has never stirred up silt. WB genny, same story.

 

[Kreole Kid]

3 years is what I follow as preventive maintenance. I watch the water pressure gauge on smartcraft. It slowly drops. At the end of the 3rd year - I had 1 fin partially missing.

I hate to sound STOOOPID but, I just figured out that the water pressure on the SC was for that purpose. Anyway what is the correct range on the water pressure?:huh:

I think the last time I ran her, she was somewhere in the low 40's range. Does this sound correct. I have new impellers and I was planning to change them soon.

 

[Jimmy Buoy]

As with most things, replacement schedules depend on usage. For me, I'm in fresh water and avoid operating in shallow sandy waters which should extend the life of my impellers in excess of 5yrs.

I see many fellow boaters heading into shallow water to anchor and reversing with clouds of sand surrounding their boats. That sand is being picked up by the intakes and will go through the strainers right into your neoprene impellers - not nice!

In my case though, I am able to check for water flow each time the engines are fired up simply by watching the thru-hull exhausts. That still doesn't guarantee proper flow once up to operating speeds, but it helps identify problems early. I have no digital instruments to see water pressure values on my year boat.

I would think 3yrs would be on the low side of expected life on these impellers.

 

[Four Suns]

Of course there was once someone on the forum here that was a proponent of the “wait till it breaks” theory…… but that’s not me.

He's since been voted off the island... I think he now provides boating advice to the Somali pirates...

 

[jpk33]

He's since been voted off the island... I think he now provides boating advice to the Somali pirates...

That explains the "cool mods" on those skiffs!

 

[Four Suns]

That explains the "cool mods" on those skiffs!

Actually... he could be our "secret weapon" on pirating... if they actually listen to him, they might just blow themselves up.

 

[Hampton]

3 years or 200 hours, whichever comes first in salt water - Absolutely not a second more. There's too much at stake. 3/2 is a stretch, but, a safe one. Don't go beyond these numbers in salt water. Continue to monitor your systems.

Also, it depends whether or not it's ok to break down. I don't like to break down. In a little over 4 years, we cruised on 16 trips, one over 1500 miles. We didn't break down. I don't change the oil every 6 months, but I don't like to break down.

 

[carterchapman]

Not only preventing breakdowns - but how much fun is it "chasing" (and removing) broken fins through your cooling system. Any impeller change - no matter how hard - is soooo much easier without that task.

3 years for "Reward's" impellers - that's about 180 hours for us.

 

[douglee25]

I replace mine annually but I definitely think it's overkill. The old impellers look brand new. I always keep the old one for a spare and throw out the prior one. I probably could go much longer, but for an hour of my time and the $40 rebuild kit, why not?

Doug

 

[Hampton]

I replace mine annually but I definitely think it's overkill. The old impellers look brand new. I always keep the old one for a spare and throw out the prior one. I probably could go much longer, but for an hour of my time and the $40 rebuild kit, why not?

Doug

Because you could be waxing instead?

 

[alvey]

Could someone provide a link to the proper impeller kit for the 05 340?

 

[Partyoffive]

How old are your pumps? That water pressure is to high. Mine was running there, My mechanic replaced pumps which were original And had to clean the heat exchangers. Now it's about 5 lbs at idle, and less than 10 under full load. The heat exchangers were the culprit on getting the pressure down. The factory mercruiser pumps are brass and the impellar over time can cut a channel in the pump thus making the impellar replacement less than optimal and a pump failure is not far behind. Pulling the pumps on the 8.1s can be a difficult job. If your pumps are original ( 10 years old?) and you are pulling them out to change the impellar, you should consider changing the pump...not cheap, as the pump can run $700- $800 for original mercruiser parts but worth the investment on an original pump iMO.