[creeky1664]

Mariah z225 - MCM 350 magnum V8 1987-1995 OF287293
so I’ve owned the boat 10 years and had many great hours of fun and spent several thousands in services and parts, but now Ive hit a problem with the starter that keeps re-occuring.
Over the last few seasons I’ve had a problem with the starter motor, not engaging, it often starts to turn over the engine giving a ‘growling or grinding' noise, sometime it starts, sometimes it ‘zings’ as the starter fails to engage.
First few seasons I just replace the starter and everything was great, last year as the engine was out of the boat I had a mechanic check the ring gear, fine, no teeth damage, but its happened again this year, so i again replace the starter. Ive had about 2 trips with maybe 10 starts and its happened again, growling or just zinging!!
my problem is I now have 4 removed starters and if I re-fitted them, they still work or start the engine but stop after maybe 10 or 15 starts, kids think the boat is jinxed and won’t come out on it as its not reliable. BTW Ive always replaced with new bolts and tightened tighttheres no water in the oil.
Help or advise please

[Hudson River Steve]

You didn't mention it but did your mechanic check the alignment of the starter pinion gear to the flywheel ring gear when the starter engages? You may have an alignment issue. There are very in expensive shims that can be added between the starter and the block to correct any misalignment.

[creeky1664]

yeah I've seen some shims on image searches but they never come with the starters that I've bought. I was kinda hoping to stay away from them. any alignment would be hard with the engine in the boat, would small washer/spacers move the starter enough?

[Hudson River Steve]

I suppose thin washers would suffice but the shims tend to be thinner and easier to install as they are slotted at one end and you only need to remove one bolt. They also have a tab at the end that allows you to hold them while installing. Any auto parts store should have them.

[creeky1664]

so i put a couple of thin washers between the starter an the bloke yesterday an although it started immediately there was a grinding noise and complete failure within 3 starts! so shims make it worse. i have found a referencer online to starter motor block failures when i googled 'mercruiser starter bracket' apparently it has been known for 350 chevy engines to crack at the starter screw thread on the block, so I'm now gonna have a look, upside down on my head with a powerful flash light.
as-well as looking for signs of any cracks or movements, I'm also looking for somewhere to attach a bracket from starter to engine block.. I've heard it might help.
Thanks for following an commenting on this thread Hudson River Steve, yesterday was 33deg C in London, it don't happen often!! an i just gotta fly around the Thames to cool down. Cheers Creeky

[Hudson River Steve]

Creek, if it is a crack in the block that's a big problem. You need to pull motor and hopefully find someone who can weld it up, if not a replacement block may be in you future. In the short term I would suggest you replace the starter bolts with studs that thread all the way into the bore. You may need to chase the threads with a tap to ensure the studs seat as far up into the block as possible. This would be a temporary fix as the crack will not stop growing. It may get you through the season. Enjoy the warm weather.

[creeky1664]

well I've videoed the area an studied it an i can't see any cracks, i put the bolds in on there own an they go in all the way to the cross hatched machined part of the long bolts and they seem secure, although the torc in the started must be huge, still considering a brackets for the starter, seem that many were fitted to early models all the way upto the 90s.
anyone ever hear of starter brackets on later models?

[scaverly]

Creeky , can you get someone to watch the starter , I know its hard to see on a 350 , to see if its flexing when you start it ? This would confirm as Steve said that something isn't right . I presume bolts feel tight , I have the same engine and I replaced my starter last week , there where no shims , but takes three hands to change it :-) Shawn

[scaverly]

BTW, 30 C here in Canada also , perfect boating weather ...Shawn