Mercruiser Starter Mag 350 - Rusty Bendix

In the last year I have replaced my starter 3 times, the dealer replaced the Mercruiser brand starter with a Sierra brand. On the first two replacement starter the Bendix has rusted to the point it no longer engages in about 3 months of use. At first the service center figured it was bilge problem and replaced my bilge pump.

While I thought it might be that Sierra produced sub-par starters. But after looking at the last starter they replaced, the only rust is on the Bendix while the starter body shows no rust, not the bendix is completely seized with rust. With this mind I am thinking that either my bellows is leaking or something else is getting water on the flywheel which is getting on the starter Bendix. Note while I do get water in the bilge, we are not talking gallons but enough to get the bilge to activate during a days use maybe a up to a gallon.

Anyone else has similar problems that they can share. One thing to add is that I had the leg replaced after it failed, two year ago at which time the bellows were also replaced. The started worked for that season though somewhat noisy.

Re: Mercruiser Starter Mag 350 - Rusty Bendix

is there any water leaking at the rear of the engine while it is running??

Re: Mercruiser Starter Mag 350 - Rusty Bendix

Water from a leaky bellows is not going to get inside the flywheel cover and cause the starter to rust unless your bilge fills up with water and it's above the bottom of the flywheel cover.
In that case, you have bilge pump problems more than starter problems. Do you ever look in your bilge to see how much water is in it? Do you have a float switch on your bilge pump?

Re: Mercruiser Starter Mag 350 - Rusty Bendix

remember that only 2 inches at the bilge pump could be 8 inches at the transom when going up on plane.

Re: Mercruiser Starter Mag 350 - Rusty Bendix

Thank you for the responses, I have around two inches at the most in the bilge, I have a new pump with a built in automatic switch. I have not seen any water leaking around the engine nor have I heard any. Water temp and water pressure are all normal as well. The engine it self has been running great this year.

So could two inches of water really splash up to the starter and get inside the bendix, there is no rust on the outside of the starter?

Re: Mercruiser Starter Mag 350 - Rusty Bendix

No ,but the water does get to the bottom of the flywheel and spins it into the bendix.Simple test is to add some water untill the auto bilge starts and stops. go to a ramp or steep hill and see how high the water is at the transom.If touching the dust cover of the flywheel you have your answer.Simple solution is to add a small bilge pump at the transon tied into you main pump.Hit the manual switch as you add power to plane.