5.7 L INBD Impeller
- Thread starter jimdavi
- Start date
Alex F
Well-Known Member
- Nov 14, 2006
- 9,166
- Boat Info
- 2005 420DB with AB 11 DLX Tender, Raymarine Electronics (2x12" MFDs) with Vesper AIS
- Engines
- Cummins 450Cs, 9KW Onan Generator, 40HP Yamaha for tender.
I've learned from other threads that some guys change them as part of routine annual maintenance, but I think the answer is "it depends". It depends on few factors like:
- how old are they?
- how many hours they we operating?
- did you ever touched the bottom and possibly had some sand/silt sucked in the engines?
- how's the engines temp holding?
I personally think that if all answers are on the positive note the impellers should last couple of years with no problems, especially in fresh waters. My boat is 2004, I got it in 2007. I don't know when, if ever, the impellers were changed. I had changed them last fall as part of winterizing procedure. When I pulled them out they looked very good, like they can go for another 2 years. But, since I don't know when they were changed last I felt it was the time.
- how old are they?
- how many hours they we operating?
- did you ever touched the bottom and possibly had some sand/silt sucked in the engines?
- how's the engines temp holding?
I personally think that if all answers are on the positive note the impellers should last couple of years with no problems, especially in fresh waters. My boat is 2004, I got it in 2007. I don't know when, if ever, the impellers were changed. I had changed them last fall as part of winterizing procedure. When I pulled them out they looked very good, like they can go for another 2 years. But, since I don't know when they were changed last I felt it was the time.
Nehalennia
Well-Known Member
- Aug 22, 2007
- 10,006
- Boat Info
- 2001 310DA twin 350 MAGs, Westerbeke 4.5KW
- Engines
- Twin 350 MAG V-drives
Mines a year old and I keep a spare aboard. I'll most likely change it before winter this year.
Go Aweigh2452
Active Member
- Aug 8, 2007
- 1,163
- Boat Info
- its in my signature
- Engines
- 6.2 Horizon MPI w/guardian system
I'm not so sure fresh or salt water has any bearing on the life of impellers. The standard rule is 2 years then change based on an annual 100 hours run time per year. Some go for many years before changing and get away with it.
I normally go by my engine owners manual. In mine it says annually...
I carry an extra...
I normally go by my engine owners manual. In mine it says annually...
I carry an extra...
Loneranger
Well-Known Member
- May 2, 2008
- 1,068
- Boat Info
- 2000 SeaRay Sundancer 270
- Engines
- 7.4l Mercruiser w/ Bravo III
You are probably more likely to suck up something (floating debris, etc) which would damage the impeller in freshwater i would imagine.
The recommendation from the owners manual is to replace every 2 years. I have replaced mine every 2 years and the old one looked fine (which I keep as a spare). But I have also replaced mine every 2 years and the old one had a blade knocked off.
John
The recommendation from the owners manual is to replace every 2 years. I have replaced mine every 2 years and the old one looked fine (which I keep as a spare). But I have also replaced mine every 2 years and the old one had a blade knocked off.
John
Keep a fresh spare set aboard.
Verify proper flow at start-up on the side exhaust and don't cast off unless this critical cooling is acceptable. This should become routine to ensure a preventable failure doesn't happen at a bad time.
Mine are only replaced when they fail. I split the raw water system and pulse flush the broken bits out of the heat exchangers.
Verify proper flow at start-up on the side exhaust and don't cast off unless this critical cooling is acceptable. This should become routine to ensure a preventable failure doesn't happen at a bad time.
Mine are only replaced when they fail. I split the raw water system and pulse flush the broken bits out of the heat exchangers.
- Nov 12, 2006
- 5,334
- Boat Info
- 1999 Sea Ray 330DA
Twin 7.4 MPI (310 propshaft HP) V-drives
- Engines
- Twin Mercury Marine marinized 7.4L L-29 V8s
Cast iron block w 4-bolt mains
Don't change just the impellers if your engines are equipped with Mercury's crappy plastic bodied raw water pump. You must change both the impeller and the plastic housing. The impeller does wear the housing. Installing a new impeller in a worn housing solves nothing and only achieves higher than normal wear of the new impeller. They should redesign the damned thing, but then they would just sell $20 impellers instead of $100 pump kits.
I talked to the Jabsco rep at a boat show and asked why they didn't make a replacement for the merc pumps. Jabsco does make a replacement for Mercs except for ones that have serpentine drive belts. He didn't know, but was going to look into it. Sure wish they would build one. If you have a boat with v-belts, you can replace the merc pump with a Jabsco, which is a much better pump.
Best regards,
Frank C
I talked to the Jabsco rep at a boat show and asked why they didn't make a replacement for the merc pumps. Jabsco does make a replacement for Mercs except for ones that have serpentine drive belts. He didn't know, but was going to look into it. Sure wish they would build one. If you have a boat with v-belts, you can replace the merc pump with a Jabsco, which is a much better pump.
Best regards,
Frank C
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osd9
New Member
For a guy who goes WAY overboard on some of your other 'mods' , that's one of the dumbest things you've said!
I can see it now....you're on your 5th year of impellers and it's only a matter of time....and then just when you are getting ready to pull into an unfamilar inlet to get out of some weather......bammmm....the port impeller goes....better hope the stbd impeller stays intack......
Replace your impellers according to the manuals....
Thanks for the concern.
Maybe I'm unlucky, but I've never made it to five years on the impellers. I usually get about two.
At least we share the concern about being forced to replace the impeller at a bad time, which is why I will always remain a vocal proponent of inspecting raw water flow at startup.
Out of curiosity, which mod(s) are WAY overboard?
Wingtard reminds me of the guy that read a book on how to swim then jumped in the water and drowned. Except in our case, he's come back to life and joined Club Sea Ray to lecture people how perfectly he can swim.
Waiting till an impeller fails... that's worthless and stupid advice.
You want to change an impeller before it fails. If you change it after two years and all the fins are on it, consider yourself lucky (and good).
The number one reason marine engines fail is due to cooling problems. It's amazing that people go on and on about the latest Slick 50 super purple synthetic poly vinyl oil they change every month but don't want to change out the impeller or keep the cooling system components in tip top shape.
Like you, I go out for long cruises and I change the impellers every year. Sometimes they are all there, sometimes a fin or two is missing, and sometimes I've completely blown them up. Picking impeller pieces out of the heat exchangers is not fun. Breaking a single fin off while underway can impede cooling.
Alot of things go into impeller life... Has the boat sat for months at a time with the impeller in one position? The impeller could set and not be doing it's job even though all the fins are on it. Have you ever had a blockage from sucking something up? Some of the fins could have flipped...
As Frank said, carrying a spare impeller alone may not do the trick. You need to make sure you have all the pieces parts and tools to do it right.
BTW.. the number 2 cause of fires on boats (per a 2002 BoatUS report) was engine and transmissions overheating. Probably from people waiting until an impeller failed... sheez...
The number 1 cause of fires on boats (55% of fires) were caused by AC & DC wiring and appliances... probably from mods by a knucklehead owner.
Waiting till an impeller fails... that's worthless and stupid advice.
You want to change an impeller before it fails. If you change it after two years and all the fins are on it, consider yourself lucky (and good).
The number one reason marine engines fail is due to cooling problems. It's amazing that people go on and on about the latest Slick 50 super purple synthetic poly vinyl oil they change every month but don't want to change out the impeller or keep the cooling system components in tip top shape.
Like you, I go out for long cruises and I change the impellers every year. Sometimes they are all there, sometimes a fin or two is missing, and sometimes I've completely blown them up. Picking impeller pieces out of the heat exchangers is not fun. Breaking a single fin off while underway can impede cooling.
Alot of things go into impeller life... Has the boat sat for months at a time with the impeller in one position? The impeller could set and not be doing it's job even though all the fins are on it. Have you ever had a blockage from sucking something up? Some of the fins could have flipped...
As Frank said, carrying a spare impeller alone may not do the trick. You need to make sure you have all the pieces parts and tools to do it right.
BTW.. the number 2 cause of fires on boats (per a 2002 BoatUS report) was engine and transmissions overheating. Probably from people waiting until an impeller failed... sheez...
The number 1 cause of fires on boats (55% of fires) were caused by AC & DC wiring and appliances... probably from mods by a knucklehead owner.
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By all means, follow the advice of the forum pot head.
My advice is to inspect for raw water flow prior to casting off and his is: “stuff don’t break at the dock”.
Instead, cast off w/ an easily detected problem and spend 15 or 45 minutes to replace the impeller, split the raw water system, flush the bits out of the exchangers, reassemble the raw water system, and then get underway.
You don’t meet the grade if you can’t complete all this in less than 15 minutes.
You don’t measure up if you can’t maintain safety to fix a disabled vessel underway for a problem that should have been detected at the dock.
All your choice, I will continue to remain the sole vocal proponent of detecting this problem at the dock.
My advice is to inspect for raw water flow prior to casting off and his is: “stuff don’t break at the dock”.
Instead, cast off w/ an easily detected problem and spend 15 or 45 minutes to replace the impeller, split the raw water system, flush the bits out of the exchangers, reassemble the raw water system, and then get underway.
You don’t meet the grade if you can’t complete all this in less than 15 minutes.
You don’t measure up if you can’t maintain safety to fix a disabled vessel underway for a problem that should have been detected at the dock.
All your choice, I will continue to remain the sole vocal proponent of detecting this problem at the dock.
Move another Four Suns topic to the bilge and create a clean Part 2 with less of his verbal diarrhea.
- Oct 6, 2006
- 12,155
- Boat Info
- 1996 450DA
- Engines
- 3116 Caterpillars
I usually stay out of these, but in this case, it is important that CSR members with less experience or those who follow the forum to learn, avoid the Wingless approach because it is based on faulty reasoning and logic. Here is why:
Wingless says don't change impellers until they fail and that checking exhaust water flow at the dock is adequate preventitive maintenance. Well, save yourself a tow bill or the agony of learning to change an impeller underway. Rubber impellers get stress cracking in them at the base of the blades as the rubber dries out and take a curved set. You may see a failed impeller cause reduced water flow, but you will will never see an impending blade failure at the dock when the blades are running at idle and not under stress. If your impeller is about to fail but still has its blades in tact, water flow will be normal. Only when you crank up the rpms and heat up the pump will the blades disintegrate.
So save yourself a real headache and follow your engine manufacturer's recommendations on impeller replacement intervals.
Wingless says don't change impellers until they fail and that checking exhaust water flow at the dock is adequate preventitive maintenance. Well, save yourself a tow bill or the agony of learning to change an impeller underway. Rubber impellers get stress cracking in them at the base of the blades as the rubber dries out and take a curved set. You may see a failed impeller cause reduced water flow, but you will will never see an impending blade failure at the dock when the blades are running at idle and not under stress. If your impeller is about to fail but still has its blades in tact, water flow will be normal. Only when you crank up the rpms and heat up the pump will the blades disintegrate.
So save yourself a real headache and follow your engine manufacturer's recommendations on impeller replacement intervals.
Here is what wingless has said:
There is no guarantee that the recommended interval will avoid headache, but following the maintenance schedules and the documented procedures is good advice. My boat has excess maintenance.
I still stand alone in recommending that raw water flow be verified prior to casting off.
Another benefit to this practice is subtle flow differences may be detected. I had observed a minor flow delta, split the pump and found part of one blade missing.
Ignoring raw water flow and using a log book / schedule doesn’t catch that problem.
Use your ocular gland and detect small problems before they melt-down!
Is it fair to conclude that you'll never grow up?
That ties to this:
Sorry it is not clear to the pot head, but this is the extent of my advice.
My recommendation is superior to ignoring raw water flow because “stuff don’t break at the dock”.
Converse48
Well-Known Member
Here's my unsolicited $0.02.
I don't think the wingless approach of habitually checking the raw water flow at the exhaust is a bad idea. If there is no flow at the dock, there certainly will be no flow at speed. That said, checking water flow at the dock should not be your only approach to determining when to change the impellers.
On my boat, I can easily hear when the exhaust fills up with water because the sound is much louder until the water flow begins. I always do this audio check. I also do a quick visual check of the flow, particularly on the generator, which has a far less robust impeller (in terms of service life) than the mains.
I am unable, however, to perform any sort of specific flow analysis visually. It comes down to: Is there water flowing? [Yes/No] Does it look "normal"[Yes/No]. As imprecise as that may be, it's still worth doing.
But as Frank reminded, just because there is adequate water flow at idle, doesn't mean it will be there when you wind them up. I'm changing my impellers annually even though the ones being removed look like new.
I don't think the wingless approach of habitually checking the raw water flow at the exhaust is a bad idea. If there is no flow at the dock, there certainly will be no flow at speed. That said, checking water flow at the dock should not be your only approach to determining when to change the impellers.
On my boat, I can easily hear when the exhaust fills up with water because the sound is much louder until the water flow begins. I always do this audio check. I also do a quick visual check of the flow, particularly on the generator, which has a far less robust impeller (in terms of service life) than the mains.
I am unable, however, to perform any sort of specific flow analysis visually. It comes down to: Is there water flowing? [Yes/No] Does it look "normal"[Yes/No]. As imprecise as that may be, it's still worth doing.
But as Frank reminded, just because there is adequate water flow at idle, doesn't mean it will be there when you wind them up. I'm changing my impellers annually even though the ones being removed look like new.
tdappleman
Active Member
- Dec 17, 2007
- 1,608
- Boat Info
- 1996 270 Sundancer
- Engines
- New twin 4.3's - 235hp each with Alpha 1 Gen 2 Drives
Jimdavi - you have received some good replies to your original question - but please ignore any advice which says to not replace something until after it has failed. Hopefully you know that ..... but just in case. I just replaced mine last fall and it was my first time. It wasn't a bad job and the parts were certainly cheap. It will now become an annual replacement item as I do not want to be in a position of having it fail out on the water. I noticed my temp gauge creeping up one time out - luckily we were close to the dock and I just turned around and we went home. After I got the impellor out one of the blades had broken off. I got lucky and found the piece before it got circulated around the engine. Definitely carry a spare - if for no other reason then you have it on hand when you need to replace it without having to order something and be down for a few days. The 'spares' kit can get pretty large after a bit but you certainly appreciate it when you need something out of it.
Now... everyone back to troll hunting.... I think one may be close....:smt024
Now... everyone back to troll hunting.... I think one may be close....:smt024
I don't think anyone anywhere ever said to not check water flow. I can do that on my generator but as I explained in all the links wingtard has pointed to, I have 1300 HP pushing gases out of 10" tubes underwater and it's pretty hard to notice if there is water flowing or not with the volume of gas coming out. But he's never been there so he thinks he's got me on being a bad boater because I left a seacock closed one time... The posts he keeps pointing to were discussions around raw water flow sensors to help detect water flow problems before they produce engine overheating problems but he wants to declare his "I never have a problem because I read a book" BS. My engines do sound different if there is no water flow.... but that's only when the exhausts are out of the water and the boat is on plane which by then has smoked them.
If you do have an impeller fall apart, back flushing will probably not remove all the pieces either. If it be my generator or my mains, I've had to pull part of the cooling system apart to get the pieces out. That's why I prefer to change them before they break.
In fact... here's a picture of some impeller/cam damage from another board member on a 480 DB that put over 3000 hours on it (the boat... not the impeller):
He must be a crappy boater too!!!! (You get all those pieces out by back flushing Matt?) I'm sure there are plenty of experienced boaters on this forum that have smoked an impeller...
The original poster wanted to know about changing impellers on a 2+ year old boat because he is going out cruising for 10 days. My answer would be "yes" because you don't want to fix it on the trip and it's probably time.
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