1994 Force 70HP Bad Cylinder

[Headponder]

Hello Everyone,

I'm looking for advice as how to proceed with this motor. Compression values are as follows-Top cylinder 0, Middle 122, Bottom 124. I removed the head and the top piston has play in the cylinder and there is a very small piece missing of the edge of the piston. The section of cylinder wall that I can see is not scored. Do I have to pull the powerhead from the outboard to remove this piston or can I access the top cylinder from behind the carb up front. Is this motor worth fixing? It is in mint condition otherwise. Any advice would be greatly appreciated as I am somewhat limited in mechanical ability.

 

[WillyBWright]

Re: 1994 Force 70HP Bad Cylinder

I would pull the carb and reed block to have a look. They're going to have to come off anyhow. You might get lucky. Zero compression concerns me however. That bad usually requires boring. Byt you never know til you get that piston out. Sometimes it's aluminum transfer from the piston to the cylinder. That can be eaten off with muriatic acid. Nastty stuff, be careful.

 

[fishkiller10]

Re: 1994 Force 70HP Bad Cylinder

New here, just getting my feet wet in the forums but.....I just picked up a boat cheap with a 1994 70 hp force on it with a blown middle cylinder. The cylinder is badly scored. It was an obvious overheat, the head was full of lake bottom dirt. It also had 0 psi compression. I considered fixing it but instead installed a 1985 85 hp Force on it that I already had. On ebay I found a dissasembled power head for the 1994 70 hp motor for $169 dollars. I tried to copy the link and put it here but it wouldn't go....but here is what it was listed under....
1994 Mercury Force 70 HP Motor Block

Good luck.

 

[BIGGILLY]

Re: 1994 Force 70HP Bad Cylinder

HELLO THEREW I HAVE A 1994 MERCURY FORCE 70 HP AND LAST SUMMER WHILE RUNNING IT I WAS GOIJNG ACROSS THE LAKE AND THE MOTOR JUST SEIZED UP UP WOULD NOT TURN OVER WITH STARTER OR BY HAND AFTER GETTING IT HOME tried turning it over again by hand and if done slow it will crank over so while doin f this i put a finger over each hole and found that the center cylnder had no compretion i have yet to do any other work to the motor and dont know if anyone else has had this problem and could tell me if it would be worth trying to rebuild the motor or just replacing the short block as a whole any help wouldbe great thank you