Re: Bought boat in July - hasn't been out of mechanic's since (on # 3 now) repairs $$
Okay, first, don't panic
What you're experiencing is actually pretty normal for someone getting a first boat, and especially someone getting a first boat that's an older pre-owned model.
Take a deep breath, let it out, and sit down and think. Figure out how much you can afford to spend to fix the boat, and when. If paying for the boat will cause you to short your family or miss some bills, then hold off a bit until you're more comfortable.
Adjust your expectations; Older boats, especially ones that haven't run in a while, can cost money to get running again. Boats in general are expensive. The only boat that's ready for the water is one that's brand new and has also had a dealer or experienced boater prep it and take it to the boat ramp for a test run. All other boats need work.
Got that? Ok, on to your problems...
As has been said, the problem with the engine killing when it goes into gear is most likely due to the shift interrupt switch being triggered. This is a little electrical switch plus some hardware on the top rear of the engine on a little platform. Two shift cables go there, one from the shift lever and one to the stern drive. When you shift, the hand lever pushes on the upper cable, which then moves part of the shift interrupt mechanism, which pushes on and moves the lower cable.
When that happens if the lower cable doesn't move, the mechanism the cables attach to pushes the switch. The switch stops the engine firing... normally this is enough to let the drive come out of gear. If the drive comes out of gear the lower shift cable is released (because it can now move the drive gears, where before they were locked together) and the switch is immediately released and the engine continues running.
If your lower shift cable (which runs from the shift interrupt switch area to the stern drive and connects there to a shaft) is worn out or corroded then it won't move easily. If that happens, the shift interrupt switch gets pressed for a long time (relatively speaking... it's a few seconds) and the engine shuts down.
The lower shift cable getting corroded is actually very common in this type of sterndrive. I had to replace mine on a boat from 1981 just last summer.
The good news: your engine is working. If the mechanic has had it running (hopefully on muffs, so he's got cooling water going in) then it's probably ok to use. When you get it, pull the dipstick out and look at the oil on it... if it looks like a milkshake, then you have a real problem. Most likely it's going to look like dirty oil, in which case the engine is ok, and the crack you see in it just needs a little plugging, which you can do with JB weld or another really good product called marine-tex.
If the mechanic rebuilt the carb, that's a good thing too. A clean, well adjusted carb will let you avoid many headaches.
More good news: If our diagnoses are correct, then your shift interrupt switch is present and working. This is good, because you can't buy a replacement for it, you'd have to scrounge parts from a salvage shop or ebay, or else buy Mercruiser's upgrade kit to use the new style switch, which would cost $120 or so, not counting labor.
Without the shift interrupt switch working, the boat would be hard to use, so that's a good thing to have.
If the lower shift cable is bad it'll need replacement. Now, you can keep paying mechanics to do this stuff, but it sounds like you're in the same boat as the rest of us, with not a lot of money to spend on that stuff.
So my recommendation is that you get the boat home, then take some pictures of it and post here for our comments, and consider doing the work yourself. It's not actually very hard (mostly annoying sometimes) and you'll save a bundle. The bulk of cost for having a mechanic fix your boat is labor, and for this type of drive unit (Mercruiser sterndrive) that can be a lot.
Many of the folks here do all their own work, and many of us weren't mechanics to start with. You can do it if you choose. Probably you'll need a weekend plus a couple evenings to do the lower shift cable. There are threads here about it, if that turns out to be the problem then we'll walk you through it. A good source for the parts you'll need is either iboats (
www.iboats.com) or ebasicpower (
www.ebasicpower.com).
If on the other hand you want to pay a competent mechanic, what you really want is a dealer of that brand of drive (Mercruiser, part of Mercury Marine) who does service. They may be a little more expensive than the mechanics you've had do work (or not) but I can guarantee they'll know the drive more than the mechanics you've dealt with so far. Let me know if you need help finding one, here's a link to a web page with the dealer's listings:
http://www.mercurymarine.com/find-a-dealer/
(make sure you check off "Mercruiser" and/or "Mercruiser Premier" on the left side in the SERVICE section). Put in your zip code and write down the dealers it finds, then call them and tell them your boat model and drive (It's a Merc 888 engine/drive combo). They should be able to give you a quote to replace the lower shift cable and bellows, probably without seeing the boat, although they will want to have a look before creating a written quote. Expect something like $500 minimum to replace the shift cable, most of that is labor. The bellows are the same or a bit more, depending.
Do post pics of the boat, engine and drive, especially the top rear of the engine, and we'll tell you what to check and how to do it. We'll also walk you through checking the rest of the boat for any problems. But it sounds like you're on your way to having a running boat, which is good.
If you don't seem to get a response here for some reason or you need a fast reply, feel free to PM me, that sends a notice to my personal e-mail right away.
Do try to answer all the questions people ask here, and do post some pictures. Use photobucket (
www.photobucket.com) as an upload site, then click the picture icon when posting here (little yellow box with a dot hovering over a mountain in it) and put in the "direct link" to the pic on photobucket, that'll insert the pic here. Post if you have problems.
Above all, relax and welcome to boat ownership
Erik