changing impellor

davis · 21 March 2010, 21:40

I have a mariner engine for 2 years, should I change the impellor before I start using the boat for this season, there is a strong tell tale . The engine is 6 years old and I dont know when it was changed. Is this job for a mechanic or would I be able to do it myself?

Nos4r2 · 21 March 2010, 21:46

Quote:

Originally Posted by davis

I have a mariner engine for 2 years, should I change the impellor before I start using the boat for this season, there is a strong tell tale . The engine is 6 years old and I dont know when it was changed. Is this job for a mechanic or would I be able to do it myself?

Change it. It's not worth the risk of not doing it.
It's not difficult, but you'll need to buy the manual for your engine before you do it.

martini · 21 March 2010, 21:52

Leave it. It works so what's the point?

davej · 21 March 2010, 22:22

If you don't know when it actually was changed after two years its vital that you change it, as if it fails it will cause your motor to overheat and seize, not good!

Best practice is to inspect every year and if ok then change it bi annually.

I change mine every year as by the time I have dropped the Lower leg off, for the £12 that a replacement costs I might as well do it.

It's a very straightforward task but I would advise that you get a manual or look on iboats.com for the DIY info.

One of the problems could be that its actually the original impellor and is in fact 6 years old.

If a vane breaks it can cause small bits to become jammed in the cooling passages of the block, another common cause of failure is that the centre bronze bush seperates from the rubber and hence doesn't pump. If it has been run at all without muffs or in water than it will have been stressed and could fail. Dropping the LU is also good practice as it prevents corrosion forming and sticking the two sections together.

Good Luck

BogMonster · 21 March 2010, 23:14

An interesting discussion this one ... I have had my boat for 4 years and never touched the impeller and I think it may even still be original which would make it 10 years old. The local diver here told me a couple of years ago that his dive rib (1995 Humber with twins) had never been touched either.

I've got a spare impeller (two, in fact, one with the complete kit) but it's a round tuit job. Or rather it was ... I've now sold the boat so don't need to

m chappelow · 22 March 2010, 17:48

i have known impellers last for many years too ,but another problem if you dont drop the lower unit every couple of years is that it can get seised on or the little woodruff key or peg that the impeller locates on can rust away if its steel .also its the upper and lower parts of the impeller that can wear out as much as the blades and the water pump lower plate ,i have bought impellers that have not been factory ones and they have lasted much longer than the dealer ones ,replaced some that would have gone on a lot longer ,,i even keep a spare impeller in the boat tool kit,

Nasher · 22 March 2010, 20:49

For the amount of time it takes to drop the leg and change the impellor it's not worth taking the risk in my opinion. Even the cost is not a lot.
I do my DT200EFI every year, and can do the whole job in well under an hour.

I also believe Engines that are not used much should probably be changed more often as the impellor has more chance to set into position.

Plus as m chappelow says, it's a good chance to free off the woodruff key and clean the scale etc off the housing and plate.

The other thing dropping the leg does is ensure the drive shaft doesn't become stuck/corroded in the Crankshaft, cleaning the end of the shaft once a year and applying grease is good preventative maintenance.

Nasher.

Downhilldai · 22 March 2010, 21:09

Quote:

Originally Posted by Nasher

...clean the scale etc off the housing and plate.

... ensure the drive shaft doesn't become stuck/corroded in the Crankshaft

Nasher.

Can't believe I'm hearing such things from a Soozook owner.

jyasaki · 23 March 2010, 15:47

The other risk is that the rubber impeller gets brittle and starts falling apart, lodging rubber "plugs" somewhere up in the power head. It's happened to at least one person I know.

jky

Dobieman · 23 March 2010, 19:10

I just changed the impellor in my Mariner 50hp four stroke.

i was really worried about doing it as i had not done one before and was thinking of paying someone to do it, but finally attempted it myself and it turned out to be really straightforward.

Nasher · 23 March 2010, 21:02

Quote:

Originally Posted by Dobieman

I just changed the impellor in my Mariner 50hp four stroke.

i was really worried about doing it as i had not done one before and was thinking of paying someone to do it, but finally attempted it myself and it turned out to be really straightforward.

Good Man

Fancyman · 12 December 2010, 05:27

when pulling a 15hp apart, to drop the box do you have to undo the 5 10mm bolts around the impeller housing and then undo the wedge shaped gear shift piece?

DJS · 18 December 2010, 19:27

The link below my be of use to you and as I am just about to service my 2001 3 cyl 90 hp mariner 2 stroke; any signposting to a cheap but reliable supplier for the water pump service kit would be welcomed!!

Cheers

http://www.youtube.com/watch?v=BiQNhFYFvdQ