Hey guys. Thanks for reading this. My boat is a 2001 Formula 260 BR with a 496 Mag. I bought it used out of a saltwater environment and the boat has about 150 hours on it now. I first had to replace the starter last year because it wouldn't even attempt to turn the motor over. I think starter number one had some internal issues. Anyway, I replaced it with starter number two, a brand new Merc starter from mercruiserparts.com / BAM Marine. That starter fixed the problem and worked for a few hours. Then one time I turned the key and heard a terrible grinding noise. I put the boat up for the rest of the season. Early this year I discovered that if I turned the motor over to a slightly different flywheel position, it would start perfectly. I have run the boat about 20 hours since then with no problems up until recently. One day at the dock it got that horrible grinding noise again so I got out the socket and breaker bar to turn the motor by hand. That time though the motor would not start and would grind no matter the location of the flywheel in its rotation. I figured that it had stripped the teeth in the starter so I ordered a new one (the third starter). On saturday I spent 2.5 hours getting the new starter in only to find that it makes the same, stomach churning grinding noise that the second starter did. The second starter that I took out looks fine except that there is some grease in the bendix end with the gear. The third starter is a Merc replacement made by Mallory. I went with that brand not to save money but to see if it might be better than the Merc unit. The gear on the Mallory starter looks to be slightly smaller in diameter than the Merc starter but still, the make the same noise when on the engine.

I had thought that there must have been a bad spot on the flywheel with missing/broken teeth. When I got the second starter out on saturday I went through the whole 360 degrees of rotation on the flywheel and looked at all the teeth. They all look good and none are missing. The starter gear seems to not be meshing deeply enough with the flywheel so that when I hit the key, they just bump past each other. The weird thing is that I don't see any way of adjusting the gear lash (I'm not sure if thats the correct term). There is no adjustment built into the starters and the bolts just thread into the motor. Am I missing something there? The Merc manual says something about replacing the shims 'if your motor has them'. I don't ever remember seeing any shims. One thing is that my 496 seems to be a very early production motor. The engine serial number starts with "0M06****". Could I have gotten the wrong part from BAM Marine? We used their part number to cross over to the Mallory starter so that could explain why the new one doesn't work either.

Sorry to be so long-winded. I appreciate any help that you can give me!!!!

starter number 1 on left, number 2 on right:



starter number 1 on left, number 2 on right:



starter number 2 on left, number 3 on right:



starter number 2 on left, number 3 on right:



box from Mallory starter:



View of flywheel teeth:

If the adjustment you need to make is minor, you may be able to just shim it. Shims are generally used to make 'small' adjustments. If it needs more than shims, then it sounds like this starter won't work.

50-863007A1 is the OEM # and looks like you have the right item. One thing that might be preventing the bendix gear from engaging is it may be too close to the flywheel gear. This is what the shims NoQuarter is talking about. However, it doesn't look like the shims are typically used in your application - unless the original starter had shims. Did the shims drop out during the original replacement? They fit between the mounting pad on the engine and the starter housing, and could drop into the bilge.

Assuming its not a shimming problem, it must be a voltage problem. Check and recheck your engine grounds and cables going to the starter. If there is not enough voltage to spin the bendix gear fast enogh, it will not engage fully with the flywheel. Check your battery and make sure it is fully charged and has at least 12.5VDC.

Let us know what you find (if anything). Good luck!

Thank you guys for your suggestions. I really appreciate them.

What do the shims look like for a 496 application? Are they washers that go on the starter bolts? I don't think that this motor ever had them. I usually notice things like that but I guess its possible that I missed them. Are the shims used to get the starter closer to the flywheel or do they only work to pull it further away? The reason that I think that the gear mesh is to loose is the wear pattern on the flywheel in the last picture. The spots on the teeth where the rust is worn off doesn't look very deep. Also, if the starter was to close to the flywheel wouldn't the gears just spin on each other instead of making a grinding noise? I'm just trying to reason this out.....

I will check the voltage of the batteries. There are two group 27 batteries in the boat and I put the battery switch on "all" meaning both batteries. They are 1.5 years old and I keep them charged up with an onboard charger. The day before this happened, they were spinning the motor over great for very fast starts. Still I recognize that this is something to check.

Any other ideas?

They typically look like this:



The hole in the shim is where the starter bolt goes.

They fit between the starter and block, and pull the starter further away from the flywheel. If the starter gear is too close to the flywheel, it will not fully engage due to a tight fit. Try one pair and see what happens. If that works, look for the old shims in the bilge somewhere.

Also make sure you are using the correct starter mounting bolts that came on the engine with the knurled shafts and that they are not bent. I would also recommend getting some rust preventative and light lube on that flywheel and flywheel teeth. To much rust! Get the salt water leaks out of your bilge when running. Just some extra points here.

Best Regards,
Ray @ Raylar

Thank you guys for your help. I bought some shims the other night and I am in the process of installing them today (kind of a disjointed day...). I'll let you know what happens.

Ray thanks for your thoughts. Luckily I only run in freshwater but the previous owner did run it for 103 hours and 7 years in the salt. What type of light lube should I run on the flywheel?

Ray is right about the bolts and also if they are not tight it will not engage ...Also ....you might have voltage issues ....you need a minimum of 9.6 volts @ the starter under load ....m

Just in case the other suggestions don't solve the problem, the flywheel and bell housing may require "dialing in".

The " dialing in" is an often over looked step during assembly. However, in your case, corrosion may have caused the fasteners to loosen.
The crankshaft centerline is starting point referance. The outside starter ring radius dimension must be .005 or less when measured from crankshaft centerline. Otherwise, flywheel rotation becomes concentric, ever changing dimensions between starter teeth and flywheel. (sometimes the starter engages and other times it grinds.)

Next, the driveplate, if equipped, must be centered, to the same tolerance.

Then, the bell housing must be located to the same tolerance. (the bell housing may have moved away from the flywheel and taking the starter with it.)

A re-torqued bell housing may create temporary starter engagement, but not best solution.

A dial indicator is typically used to center all components.

There are locator dowels in the block that hold the bell housing. If either the dowels or bell housing bores are worn, it becomes nearly impossible for the bell housing bolts to hold the bell housing centered.

Unless these steps are performed, other resultants include concentric vibration, bearing side load, main seal leak and etc.

I happen to have several NEW sets of fixtures, dowels and collars for locating the bell housing to NEW.... Align honed blocks should be checked also. And, new builds.

arrover, Did you find the problem ?