Impeller Lessons for all

[brimanst]

OK, at least for me. I have been having problems with my port motor overheating at cruising speed. It idles fine, and if I go at 1000RPM everythinf is normal. Coming from gas engines, things seem to be quite different. When an impeller is bad, the engine overheats at every RPM. I am amazed at the performance of BAD impellers on my CAT engines. If you look at the port Impeller, there are NO fins left at all, yet it still ran fine at lower RPMs.

I have included pictures to you can learn from my mistakes.

 

[Morpheus]

:thumbsup: Good photo now atleast I know what they look like.

Now how about a video of how to replace it on my Mercruiser 5.0L Engine :grin:

 

[RT 240SD]

On topic: How old were those?

Off topic for Morph:

5.0 is pretty easy. Search and you will probably find (can't remember if previous board or this one.)

Open engine cover, take off fiberglass piece in front of engine. Deep dive on the lower left to water pump. Unhook from bracket and hoses, pull it out, undue the bolts holding the case together, drop in new impeller. Reassemble.

Not sure if I'm missing anything, but that's really it. You will have bloody knuckles. Check hoses carefully afterward so the boat doesn't sink.

 

[jrcinnh]

Come on, you can get one more season out of left one and the right one is barely broken in. :smt043 :smt043 :smt043

Seriously, how many hours on those?

RT240, when you install the new impeller, do you have to twist them the right way?

 

[Morpheus]

So I guess me next impeller questions would be.

1. Is it one size fits all?
2. Are they hard to come by meaning if I find them go ahead and buy a few?

 

[osd9]

So I guess me next impeller questions would be........ Are they hard to come by.....?

Only when you need them....

Seriously, they are a stock item that you shouldn't have any problem finding. A member of your spares box for sure!

Replacing an impeller is a DEFINITE maintenance item. There are many timeframes for changing them. Anywhere from every other year, to every 4th year, to when the steam comes from your engine.

I have gotten by changing mine (on gas I/O, gas inboards, and outboards) every third year. I just replaced the impellers on my Diesel Inboards this spring. If you change your impeller, and it still looks good, you should pat yourself on your back. Waiting for the impeller to tell you when to replace it can have some "interesting" consequences....not to mention expensive.

 

[Presentation]

:thumbsup: Good photo now atleast I know what they look like.

Now how about a video of how to replace it on my Mercruiser 5.0L Engine :grin:

ummmm, we would need to know what drive you have.

Alpha vs Bravo

Hire it done and wach'em do it.

 

[Morpheus]

:thumbsup: Good photo now atleast I know what they look like.

Now how about a video of how to replace it on my Mercruiser 5.0L Engine :grin:

ummmm, we would need to know what drive you have.

Alpha vs Bravo

Hire it done and wach'em do it.

Bravo III (it's in my signature :grin: )

In another thread I offered someone a 6pack and help doing maint on their boat if I could watch and learn but no one took me up on my offer.

EDIT: :smt021 Sorry forgot signatures don't show up when someone puts in picture in a thread.

 

[brimanst]

Waiting for the impeller to tell you when to replace it can have some "interesting" consequences....not to mention expensive.

This is true, as that last picture of my post are the parts/pieces of the impeller that I had to dig out of my aftercooler, which weighs about 150 lbs and requires $225.00 worth of gaskets to replace it. The labor is all me and man is it hot in the south lately :smt013 which is even more of a hassle.

BTW the impellers for my boat are $250 ea. bigger boat........bigger :smt021 .

briman

 

[MadDog]

I just replaced my impellers at 300 hours which was about 3 years of service life, and they were in reasonable shape - I wouldn't want to go much beyond that though.

Those impellers of yours must be quite old!

 

[brimanst]

Well, as I looked at the old log, it appears that they are around 5 or 6 years old. I was so impressed with the maintenance log that came from the old owner, I did not actually audit it to see what really needed to be done. Rest assured I won't be making that mistake again.

It does lend to a minor design change that could prevent major problems though. The raw water pump directly feeds into the aftercooler. Why does not CAT put some sort of serviceable screen in between a rubber impeller and a major engine element such as the aftercooler?

What year/model boat do you have?

 

[MadDog]

(I don't know why my signature isn't showing with that info, but...)

I have a 2004 480DB with Cummins QSM-11s rated at 660hp.
Now at about 350 hours.

Mods I've made include adding an inverter and a cell phone booster.

mark

 

[Skip]

I carry spare impellers for mains and genny, and at 44 bucks a pop, plan to change my main impellers each year. The Cummins cooling system is not as robust as an equivalent Cat cooling system, according to my sensei, so a Cummins engine will be far more susceptible to damage if an impeller goes south during a hard run if you can't shut it down quickly.

new impellers each year are for me cheap insurance.

regards
Skip

 

[BrentJones]

On topic: How old were those?

Off topic for Morph:

5.0 is pretty easy. Search and you will probably find (can't remember if previous board or this one.)

Open engine cover, take off fiberglass piece in front of engine. Deep dive on the lower left to water pump. Unhook from bracket and hoses, pull it out, undue the bolts holding the case together, drop in new impeller. Reassemble.

Not sure if I'm missing anything, but that's really it. You will have bloody knuckles. Check hoses carefully afterward so the boat doesn't sink.

This is on a bravo III? I found instructions here http://www.mercstuff.com/waterpumpinst.htm but is this for alpha drive?

 

[RT 240SD]

5.0 w/ BIII the pump is on the front of the engine rather than in the drive. Look on the lower starboard side of the engine... it's the lowest pulley if I'm recalling correctly.

 

[BrentJones]

5.0 w/ BIII the pump is on the front of the engine rather than in the drive. Look on the lower starboard side of the engine... it's the lowest pulley if I'm recalling correctly.

So this is relatively easy to do? I'd like to start changing my own. I just had mine replaced by the dealer. It was starting to break a part but I caught it before it was completely useless.

 

[wish2fish]

....So this is relatively easy to do? .....

yeah if your are a contortionist! there is no room in my engine compartment for me to get my arms in there. I don't know how my mechanic did it. The only way I figure he got in there was to get inside the storage area and reach through the wall opening on the starboard side of the motor around to the lower front.

 

[tphinney]

does anyone out there have recommendation on a good manual that show's you how to do the impeller change out and give you a list of the supplies and tools youll need.

I noticed my Water pressure dropping over the last couple of outings so I know my impeller is getting ready to go on me. Any and all help would be appreciated.

 

[Hampton]

Tom,

I fear it is going. The pressure probably wouldn't go down until it begins to fragmant.