1978/1988 mercury outboard difference,help

[ducerman]

Hello everyone, i need some help from the pros! I currently have a 1978 checmate boat with a 1978 merc 200 hp OB. The motor has very little compresion and all in all is not in the best shape. I found a 1988 merc 200 hp on craigslist for $1500 and im thinking about buying it. I was told the motors were the same, with the same mounts. This motor came off a bass boat and has a 20" shaft. I believe mine is a 25" shaft?? It just looks to be longer. Unfortunitly the motor is 100 miles away and all i have is a few pictures to look at. It looks to be identical except for the transome mount and length. Was there a big change between these years? Would it help more if i took the vin #s and let the pros identify them? The yellow boat is mine and the other pic is the bass boat. If i need to supply more information just let me know. Thanks everyone!

 

[Faztbullet]

Re: 1978/1988 mercury outboard difference,help

Was there a big change between these years?

There are quite a few differences: The cylinder heads are different as the 1978 bolts to the inner cylinder sleeve wall and the 1988 bolts to the outside of block casting, the wiring harness is different, the 1988 has oil injection and internally mounted trim where the 1978 uses pump in boat and premix, the cooling system is a little differently plumbed on the 1978, the 1988 has a enrichener(choke) where the 1978 has choke flaps. They are both chrome bore engines and a compression and leakdown test needs to be done before purchase and the chrome bore blocks are very expensive to repair....

 

[ducerman]

Re: 1978/1988 mercury outboard difference,help

Thank you for the reply.. I was wondering, if the motor came with all of the transome mounts and hardware, would this be a difficult process to replace everything? steering and all? I know that i wont have enough money to replace or fix the powerhead and this task might be worth doing. My only concern is it being a 20" shaft and i have a 25. Thanks!