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#484225 - 04/24/10 03:21 PM Re: Mercruiser Bravo Three Maintenance Intervals [Re: Titanium]  
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Titanium Offline
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Titanium  Offline
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Northern California
Guys,

Resurrecting an old thread, and getting back to the original topic, I just dropped off our boat to the dealer for the annual maintenance. We had skipped maintenance last year due very few boating hours, so I really wanted to get the maintenance back on track for this boating season.

Truthfully, I had completely forgotten about changing the checking/changing the impeller. The dealer asked me how many boating seasons we had on the boat, and when I replied that there had been three boating seasons, he strongly recommended an impeller change.

I am tempted to let the impeller go for another year, as we only have about 70 hours on the hourmeter. But the dealer service manager pointed out that, in his opinion, just setting for x number of years can put a "cup" into the impeller vanes. So I had him go ahead on the impeller change.

I am less than thrilled at the $265 cost for changing the impeller though. sick I had always thought that the impeller would be changed with the pump left in place, but the service manager said that, at least on our boat model, that his techs remove the pump from the engine and replaced the impeller on the bench. Does this sound right?

I did ask for his techs to save me the old impeller so 1) I would get an idea of what 70 hours and 3 years of use looked like, and 2) if in good condition, it would serve as an emergency spare.

Thanks!


In theory, there is no difference between theory and practice. In practice, there is.

07 Cobalt 240 w/ Merc 496 Mag MPI V8 Bravo 3
05 Dodge Ram 1500 QuadCab 5.7L V8 Hemi
07 SeaDoo Wake 215, 1996 SeaDoo GTX, 05 HD Dyna SuperGlide
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#484230 - 04/24/10 04:39 PM Re: Mercruiser Bravo Three Maintenance Intervals [Re: Titanium]  
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tpenfield Offline
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Cape Cod, MA
I could change an impeller for the cost of the impeller ($35) plus 3 beers.

$265 is probably about right. Changing the impeller is a P-I-T-A. The pump has to come out . . . that takes about 1 hour. Then the impeller has to be changed . . . 1/2 hour. Then the pump has to go back in. So, 2-1/2 hours +/-.

There is no possible way to change it while it is in the boat.

70 hours is about right, I would not go another season without changing it.


Regards, Ted

Formula 330SS

My Boat Web Sites
#484233 - 04/24/10 05:30 PM Re: Mercruiser Bravo Three Maintenance Intervals [Re: tpenfield]  
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etyppo Offline
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etyppo  Offline
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Northern California
I'm due to change mine too, and it does not look like fun on the 496. The pump is way down low on the right front of the motor. Much easier to do on a Volvo. I usually do stuff like that myself, but I may farm it out as it is hard to see what you're doing, which increases the difficulty level by about 300% if you've never done one before.


2006 Cobalt 263 Mercruiser 8.1
#484234 - 04/24/10 05:42 PM Re: Mercruiser Bravo Three Maintenance Intervals [Re: etyppo]  
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prober Offline
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prober  Offline
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Eastern Washington
If the water you boat in is clear rather than silty and you don't run into or very near sandbars then it may have gone another season but I wouldn't chance going more than 3 years. Much cheaper to replace it a bit too often that to pay someone to try to flush out the broken pieces when it lets go.

#484236 - 04/24/10 07:52 PM Re: Mercruiser Bravo Three Maintenance Intervals [Re: prober]  
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Budds Outlet Offline
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Budds Outlet  Offline
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Puget Sound, Washington
Thanks for all the info on this thread. I am now even more firmly convinced to have the impellor changed this week. It has been three seasons.


1990 Sea Ray 270DA
#484269 - 04/25/10 10:41 AM Re: Mercruiser Bravo Three Maintenance Intervals [Re: Budds Outlet]  
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lg260ss Offline
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lg260ss  Offline
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I change mine every 2 seasons. Some people change it every season. 3 years seems too long for me especially considering the amount of time your boat sits.
I agree with the previous posts about it being a PITA and also about it being a much easier job on the Volvo. Merc puts it in a very hard place to reach so $265 seems about right.


2013 Regal 28 Express, Volvo Penta V8 380 DPS
2005 GMC Sierra 2500HD
#484281 - 04/25/10 02:58 PM Re: Mercruiser Bravo Three Maintenance Intervals [Re: lg260ss]  
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Titanium Offline
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Titanium  Offline
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Northern California
Wow, what a great response from everyone. I really appreciate it.

So it looks like the consensus is that three years is as good of a time as not to have the impeller changed out. And that the estimated price is not too out of line for the work (and location) involved. If I had a little more time, I would have like to have a go at it myself, but I'm running out of time before boating season starts (which was several months ago, darn it).

Is anyone interested in the condition of the impeller once I have the old one in hand?


In theory, there is no difference between theory and practice. In practice, there is.

07 Cobalt 240 w/ Merc 496 Mag MPI V8 Bravo 3
05 Dodge Ram 1500 QuadCab 5.7L V8 Hemi
07 SeaDoo Wake 215, 1996 SeaDoo GTX, 05 HD Dyna SuperGlide
#484358 - 04/26/10 12:13 PM Re: Mercruiser Bravo Three Maintenance Intervals [Re: Titanium]  
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Just Bob Offline
Cap'n of all things wet
Just Bob  Offline
Cap'n of all things wet
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Chalfont, PA
I changed mine after 3 seasons, and it looked pretty good (only like 100 hours on it). Since I already had it all apart and had the new one in hand, I figured I'd replace it anyway and keep the old one as a spare.

Once you remove the bolts from the cover, the pump housing comes off pretty easily, so it just makes sense to pull it and replace the impeller on the bench.


"Annabo": 2005 Larson Senza 206 w/5.0L Bravo III
#484364 - 04/26/10 01:18 PM Re: Mercruiser Bravo Three Maintenance Intervals [Re: Just Bob]  
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referman Offline
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referman  Offline
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Exeter, CA
Titanium,

Did you install the Smartcraft gauges? I ask because I just bought the SC1000 Tach and speedo to install on mine. I wanted mine to better manage fuel consumption across to Catalina.


Larson Cabrio 274 350 MAG MPI Bravo III
F-250 Diesel
DURAMAX DIESEL 4X4
BMW 750i
"73" Landcruiser

"All I ask for is a tall ship and a star to steer her by" - John Masefield
#484365 - 04/26/10 01:38 PM Re: Mercruiser Bravo Three Maintenance Intervals [Re: referman]  
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Justified Too Offline
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Justified Too  Offline
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Colorado
Changed my impeller on our B III after boat was 5 yrs old with around 175 hrs.

There were some cracks in the rubber starting to appear, but just barely. Like Keith, was concerned as we are in sand sometimes that I thought may be chewing it up, but no signs of it.

I would say the 3 yr mark is a good call.



'Justified Too' - 2003 Chaparral 220 SSI 350 MAG/MPI BIII
#484489 - 04/27/10 02:48 PM Re: Mercruiser Bravo Three Maintenance Intervals [Re: Justified Too]  
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WayWeGo Offline
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WayWeGo  Offline
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Oakton, VA
Changing the impeller on a big block builds character, especially on the water with a hot engine!

Frequency and cost seem in line to me, but I also do mine for much less as I supply the labor. It is much easier to change the impeller before it comes apart. Once it grenades, you have to carefully find all the pieces and get them out of the cooling system...



1975 Trojan F36 Convertible, Twin Chrysler 440's
2014 West Marine AL360 Inflatable, 1966 Mercury 6HP, 1992 Mercury 20HP
#484620 - 04/29/10 12:33 AM Re: Mercruiser Bravo Three Maintenance Intervals [Re: Justified Too]  
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Budds Outlet Offline
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Budds Outlet  Offline
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Puget Sound, Washington
My mechanic changed my impellor today, and at 3 seasons and 105 hours the timing was just right. It wasn't showing any cracks but it was becoming stiff. I'm pretty sure it would have failed this season.


1990 Sea Ray 270DA
#526259 - 01/03/12 04:30 AM Re: Mercruiser Bravo Three Maintenance Intervals [Re: Titanium]  
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aussiesteve Offline
Warrant Officer
aussiesteve  Offline
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Posts: 2
Melbourne, Victoria, Australia
Hi all,
My impellers are lasting up to 30 hours (3 months) I am in dirty/sandy water often. Every second impeller replacement is a complete pump replacxement due to scoring.

I am toying with retrofitting a closed loop fresh water cooling system or just fitting raw water strainers.

Your thoughts, opinions and experiences would be of great help to me.

Running a 2006 5.7 MPI in a Maxum 2600SE.

Thanks and Regards
Steve.


A presumption tends to end up being a severly erred assumption.
#526260 - 01/03/12 04:42 AM Re: Mercruiser Bravo Three Maintenance Intervals [Re: Titanium]  
Joined: Dec 2002
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Admiral

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Posts: 3,675
Cyberland
A closed cooling system would not alleviate the problem as you would still be pulling in raw water to circulate through the heat exchanger. Although, I'd still go with a closed cooling as you would then not be running the sludge through your engine and clog up the passages.

For impeller longevity a strainer might help, but I am not sure by how much. It depends on how fine the particles are. You'd then need to clean it often so that you do not overheat the engine due to lack of flow.


Mike

BoatingABC.com
My imaginary friend thinks you have serious problems.
#526261 - 01/03/12 05:36 AM Re: Mercruiser Bravo Three Maintenance Intervals [Re: Titanium]  
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aussiesteve Offline
Warrant Officer
aussiesteve  Offline
Warrant Officer

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Melbourne, Victoria, Australia
Thanks for that,
This is the first boat that has reacted to my usage in this way.
Old OMC handled the dirt well and my earlier Merc470 had no problem.
I guess everything is throwaway now days.


A presumption tends to end up being a severly erred assumption.
#526264 - 01/03/12 06:42 AM Re: Mercruiser Bravo Three Maintenance Intervals [Re: aussiesteve]  
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Dave R Offline
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Dave R  Offline
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Raymond NH
Originally Posted By: aussiesteve
Thanks for that,
This is the first boat that has reacted to my usage in this way.
Old OMC handled the dirt well and my earlier Merc470 had no problem.
I guess everything is throwaway now days.


This combo might last a lot longer: http://www.ebay.com/itm/Mercruiser-Bravo...vxp=mtr#vi-desc

http://marinepartssource.com/newdetails....20Double%20Flat


"Mischief Managed"
2000 Regal 2550 LSC
7.4 MPI Bravo 3
#569250 - 09/23/17 06:46 PM Re: Mercruiser Bravo Three Maintenance Intervals [Re: Titanium]  
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Titanium Offline
Admiral
Titanium  Offline
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Northern California
So this is a really old thread, but since I am the original poster I am going to let it slide.

The impeller change back in 2010 ended up with the impeller looking brand new. I have kept the used impeller for the last seven years as an emergency backup.

Fast forward to today and now that 2010 impeller is seven years old and probably overdue for replacement. I have no hint of overheating whatsoever. The old impeller has about 100 hours of engine run time on it.

I have a new mercruiser impeller kit 47-8M0104229 (supercedes the 2010 impeller kit 47-862232A2) which includes an impeller and preformed o-ring. The new kit was $31 delivered from amarina selling on eBay, whereas the 2010 kit was $30.95 pretax at the dealer. I'm sure the dealer cost today would have been much higher.

I have the Mercruiser Service Manual Number 30 for the 496CID/8.1L Gasoline Engine, but I can't find any info in there on the procedure for changing the impeller. Section 6 in the service manual is for the Cooling System, but there is only Chapter A -Closed Cooled Models (which mine happens to be). Section 6A does mention the Seawater Pickup Pump Maintenance, but literally all it says is "whenever insufficient water flow is suspected, seawater pickup pump should be disassembled and inspected."

There is a removal/installation section on page 3A-41 for the Water Circulation Pump which appears to be on the closed cooling side of the heat exchanger. No info in this section on impeller replacement.

Does my new impeller kit go on the Seawater Pickup Pump or the Water Circulation Pump?

Somehow I expected the factory service manual to be a little more detailed. What am I missing?


In theory, there is no difference between theory and practice. In practice, there is.

07 Cobalt 240 w/ Merc 496 Mag MPI V8 Bravo 3
05 Dodge Ram 1500 QuadCab 5.7L V8 Hemi
07 SeaDoo Wake 215, 1996 SeaDoo GTX, 05 HD Dyna SuperGlide
#569251 - 09/23/17 08:08 PM Re: Mercruiser Bravo Three Maintenance Intervals [Re: Titanium]  
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Justification Offline
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Justification  Offline
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Fruit Heights, Utah
On Pier Pressure we have closed cooling systems on the inboard engines, so hopefully I understand what you are asking.
Our impellers are on the Seawater side of the cooling system, while the closed portion of the system is run exactly like a car engine, with the water pump that is mounted on what would be the forward or fan side of the block.
The impeller circulates cold sea water through the heat exchanger much as air blows over the radiator on a car, while the Water circulation pump circulates antifreeze through the block and into the closed side of the heat exchanger.
Word of warning: make sure you put the seawater hoses back on the impeller housing properly. We've got counter-rotating engines and my BIL confused left hand rotation with left hand engine, and right hand rotation with right hand engine.
Impellers only last about 56.5 seconds if the hoses are put back such that the intake side of the impeller is trying to push against the seawater, and trying to suck the water from the heat exchanger.
I guess what I'm trying to say is use the portion of the manual that talks about the seawater side.


Beer makes you feel the way
You should feel without beer.
#569252 - 09/23/17 08:49 PM Re: Mercruiser Bravo Three Maintenance Intervals [Re: Titanium]  
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Titanium Offline
Admiral
Titanium  Offline
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Northern California
Justification,

Thanks for the help. So my impeller kit is for the seawater pickup pump. And it sounds like the closed loop water pump doesn't require maintenance.

Unfortunately the factory service manual has literally nothing about the seawater pickup pump.

Well, not exactly nothing. It did offer this helpful information - "whenever insufficient water flow is suspected, seawater pickup pump should be disassembled and inspected." gunner2

And there is no information about impeller changes in the Mercruiser maintenance manual that came with the boat, other than a recommended replacement interval.

Last edited by Titanium; 09/23/17 08:49 PM.

In theory, there is no difference between theory and practice. In practice, there is.

07 Cobalt 240 w/ Merc 496 Mag MPI V8 Bravo 3
05 Dodge Ram 1500 QuadCab 5.7L V8 Hemi
07 SeaDoo Wake 215, 1996 SeaDoo GTX, 05 HD Dyna SuperGlide
#569258 - 09/24/17 08:33 PM Re: Mercruiser Bravo Three Maintenance Intervals [Re: Titanium]  
Joined: Jan 2003
Posts: 1,484
Lou C Offline
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Lou C  Offline
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Long Island NY
Honestly that is surprising, I'd expect that from an aftermarket manual, but not an OE manufacturer's shop manual. I change mine on my OMC Cobra about every 3 years, I change the impeller, wear plate and the o ring gasket for the housing. It takes all of 15 minutes because it is hidden under a plastic cover at the end of the upper gear housing. 3 bolts cover comes off, 3 more bolts impeller housing is off. If you're careful you could tilt the drive all the way up and do it in the water if it was an emergency. Even the ones I change at 3 years still look new. I probably could go longer.


88 Four Winns 200 Horizon 4.3 OMC
98 Jeep Grand Cherokee 4.0 Six Selectrac
07 Jeep Grand Cherokee 5.7 HEMI Quadradrive II
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