1997 force 75hp need expert advice

san dimas

Petty Officer 1st Class
Joined
Jan 20, 2012
Messages
369
My 1997 Force 75hp 3 cylinder has a dead cylinder because of water getting in the cylinder. Compression check showed 135 top, 130 center, and 135 bottom. I replaced the head gasket anyway. Checked the cylinder and didn't see any cracks. The old gasket was nasty but seamed to have a seal all the way around. Started it up, same problem. Runs good for about a minute and then loses the top cylinder. The spark plug has water on it again. Now I'm thinking it's the exhaust plate that is leaking water into the exhaust port. Easy enough to check except all of the bolts (about 18 of them are corroded into the block. 3 of them came out easy and the rest not. I broke off two heads while using penetrating oil, shock, and heat. Now I'm thinking of breaking every head off and drilling them all out. I own a machine shop so I have the capability to do it, not that I want to. Am I on the right track or am I making the problem worse? Also, I can't think of any other reason why there would be water in the number one cylinder. Any suggestions would be greatly appreciated.
 

pnwboat

Rear Admiral
Joined
Oct 8, 2007
Messages
4,251

Frank Acampora

Supreme Mariner
Joined
Jan 19, 2007
Messages
12,004
Re: 1997 force 75hp need expert advice

There is not a lot of meat on the bolt bosses for the exhaust cover. Thus, drilling and heli-coils are really not a good idea. Besides, the heli coils will not seal against the gasket for water intrusion.

HOWEVER: The bosses are deep and go all the way to the cylinders. Thus, you can accurately drill out the snapped bolts, drill deeper, tap 1/4-20 and use longer bolts. Coat bolts with silicone RTV to prevent further corrosion.

IF the snapped bolts have about 1/4 inch exposed, it is possible to remove them with a Vice-grip and heat since aluminum expands a lot more than the steel bolts. Sometimes an impact gun will remove corroded bolts without snapping them.
 
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