Impeller?

mattias

mattias

Member
Jan 27, 2019
105
Powell, Ohio
Boat Info
240 SD

Tow Vehicle = 2014 Diesel Grand Cherokee
Engines
350 Mag
Bravo III drive
Can the impeller on a mercruiser 350 magnum (2005 searay 240sd) just go bad? The engine is overheating. Have changed thermostat with no luck

We just purchased the boat and all ran just fine when we took it out for the sea trial (oct.). Boat never touched water again.

Impeller?
 
mattias said:
Can the impeller on a mercruiser 350 magnum (2005 searay 240sd) just go bad? The engine is overheating. Have changed thermostat with no luck

We just purchased the boat and all ran just fine when we took it out for the sea trial (oct.). Boat never touched water again.

Impeller?
Click to expand...

Depending on how it was stored in the off-season (i.e. cold, dry), the first crank of the year can easily rip impeller vanes off, especially if the impeller had some hours on it. Pull the raw water pump and verify impeller health--it's the next likely culprit.
 
Thanks! Is this a newbie DIY job I can do?
 
Remove the bulkhead in front of the motor and you can lay on the floor, reaching your arms into the bilge to do the work.
 
mattias said:
Can the impeller on a mercruiser 350 magnum (2005 searay 240sd) just go bad? The engine is overheating. Have changed thermostat with no luck

We just purchased the boat and all ran just fine when we took it out for the sea trial (oct.). Boat never touched water again.

Impeller?
Click to expand...
It is probably your seawater pump, not the engine circulating pump. The seawater pump is a belt driven accessory, on the lower starboard side of the motor. The engine water pump is the same as on a car motor.

Seawater pump impellers go bad, I change mine every other year. If pieces are missing from the impeller, they should be found. They can clog cooling passages and cause big problems.

You should never run start the motor dry, water is the lube that prevents impeller damage.
 
i had a problem with this once years ago on previous boat. i tried winterizing out of the water and didnt know the boat picked up water through the outdrive and also a through hull sea cock. fried the impeller. this was referred to as a dual pickup. check and make sure sea cocks are open
 
Change your impeller every season or every other. Better to do it in the driveway than on the water.
It is a very straight forward job... skill level two beers!

They will go bad and the will do it when your on the water. Keep a spare in the boat and learn how to replace it.
 
mattias said:
Can the impeller on a mercruiser 350 magnum (2005 searay 240sd) just go bad? The engine is overheating. Have changed thermostat with no luck

We just purchased the boat and all ran just fine when we took it out for the sea trial (oct.). Boat never touched water again.

Impeller?
Click to expand...
I am in Central Ohio area, just purchased your same boat, only 04, late last season. Where do you plan on taking it? We had ours out 3 times last year, then had the marina change out our impeller just because after advice on this board and talking to other boaters. They did some other maintenance items as well as winterizing for us...I hope to learn to do a lot of those items on my own.
 
SeaRay of Cincy was the broker for our Sun Deck. We just dropped it back to them yesterday as the entire water pump needed replaced. GREAT TEAM of people down there!
 
I changed my impellers today. One motor is a two beer project. The other one Is five beer minimum. I also found a leak behind the pulley on one motor so I’m going to replace that pump as well
 
The 2005 should have smartcraft gauges, which will show you the sea pump pressure in PSI. You should have a minimum of 1-2 PSI at idle, and 7-11 underway.
 
I'm new to site; bought a 92 sundancer, (single engine bravo I 7.4) end of lasat season. Stored in my yard in winter. ran salt away through engine and pump seemed to be wotrking good. I was suppose to launch tomorrow but tried to run (with muffs) two days ago and it wouldnt pump. Figured id try to replace impella. Above indicates its an easy job. I must be doing something wrong. Took forever to get off and i had to dremel tool the impella off. Tried everything and couldnt line things up to replace screws then I realized (i think) that belt shuld have been taken off. Couldnt figure out how to loosened belt loosened 5/8 bolt on idler but still was hard to get off (priedit off idler). I was then finally able to get the pump housing back on but cant get the belt back on. read on another site that the idler stud is suppose to have 5/16th hex that loosens it but mine doesnt have a hex (and looks like it never did) and loosening the 5/8 nut doesnt seem to help. What am I missing??
 
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Check out You Tube for your impeller change. It is quite easy. I do my sea water pump impellers on 496mags (BrIIIs) in bout 40 minutes each. Stbd takes a little longer than port as less room to work. Make sure you put a little dish soap on the impeller when you install it in the pump. It lubes it when you re start engine to prevent damage as it primes.
 
Korkie; can you send link. do you have to remove any belts to do it. You prop have amulti pulley serpantine on your BrIII i a have a seperate belt for my bravo1 with idler arm (I assume no number means 1). My prob is loosem]ning the idler to get the belt back on.
 
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