3.0 merc cruiser not starting

[astull]

I have been helping my brotherinlaw work on his 3.0 merc cruiser the problem we are having is when we try too start the boat it is making a really loud squeiling noise we thought it was the starter so we put a new one on and it is still doing the same thing anyone have any idea what it could be

[gonzo]

Is it turning at all? If not, it sounds like a loose ring gear.

[CDK]

Check if the belt moves and the pulleys turn during starting. Such noises usually come from any of the peripherals where a sleeve bearing got stuck. The water pump is a Number 1 suspect, followed by the power steering pump ( if it is a 3.0LX) and the alternator.

[PAR]

Nothing personal Astull, but you took your "swing" at it and came up short. Now it's time to let a professional spend 5 minutes with it, which most likely will be all it takes to find the problem.

In other words, if you'd had followed standard practices and procedures, you'd have known it was (or wasn't) the starter, before you replaced it. For example, with the starter off the boat, you could have taken a big screw driver to the ring gear and likely discovered just what Gonzo suspects. At the very least, you would have been able to cross this particular difficulty off the list of possible causes, rather then just toss new parts at it, until it goes away. Most reputable parts houses, will test the starter before selling you a new one, at least they should, if you haven't. It's a lot cheaper then a new starter too.

Most shops charge about 50 bucks to diagnose situations like this, which is also cheaper then tossing more parts at it until "you've got it". If it's fairly simple you can change out whatever it might be.

[astull]

Thanks for the advice I had to leave before he finished the starter job so im not sure if the pulleys were spinning our not.But now I have something to look for and the reason the pros are not working on it is because they had a shot at it ounce in the spring they thought it was the starter they replaced it and it lasted about a month and there is really no other marine mechanics in our area that are willing to work on location.We tested the starter ourselves and it was bad so we thought for sure that was the problem.

[pistnbroke]

A lot of pre engaged starters have an overload clutch ..could be that and all have a freewheel which can slip ......but please answer the simple question can you turn it over by hand? You imply it was running " but the starter motor only lasted a month" You could knock all the drive belts off to eliminate them but as the starter is at the other end of the engine its should be easy to tell whats making a noise ...a bit of paint on the ring gear will tell you if its slipping and if it is a bit of weld will hold it