View Full Version : 1984 115hp merc

04-27-2003, 08:36 AM
" looking @ purchasing a 1984 115HP merc from a local boat dealer. They gave the engine a once over & motor looks in mint shape with strong compression. they are asking $3,000.00cdn(1,800us). Is this a good price? I will be trading in my 1983 80hp merc. I need more power for my 18.5foot starcraft aluminum. Any one have one of these big six motors? I have heard they are harsh on gas is that true? Any word of advise would be appreciated. "

04-28-2003, 09:23 AM
" Jeff;You are thinking about spending $3000.00 for a 20 year old Mercury,what does the "BLUE BOOK" or the "BUC BOOK" say it's worth,seems very expensive to me!! Zeke "

04-28-2003, 09:27 AM
Jeff;Sorry I didn't see that you were talking about canadian money. Zeke

04-28-2003, 02:26 PM
" I have an old stack six merc on a aluminum boat, the motor is heavy, drinks alot of gas, and has spent as much time in the shop as it has on the water. That is pretty bad considering where I live, where have great boating weather here almost 9 months of a year. The problem that I had the most was with the top cylinder over heating. It is a long ways from the foot of that motor to that top piston to be pumping water. Also a motor of that age, the H.P. is rated on the power head, versus the newer motors are rated on the prop. That 115h.p. is probably putting out 90 at the prop.

My advise, you can spend the money now, or you can spend it later. Stay away from the old mercs! "

04-29-2003, 05:23 PM
" Jeff,

That seems a bit high to me. What sort of warranty is the dealer offering you for that price? Also, sometime around 83/84 was when the rating changed from the crankshaft to the propshaft. The performance difference between the two engines is pretty noticeable although they look pretty much identical. Make sure they and you know exactly what this motor is.

You can help the overheating problem on #1 by moving the tell tale output to the top cylinder. This allows the block to fill fully with water and allow steam to escape. Many of the older Mercs have a screw in plug for the water pressure guage. Easy to add if it doesn't already have it. Use a 90* nylon fitting in the hole and block off the old location with a plug.

Just my $0.03 worth...

Kirk "

05-01-2003, 09:42 PM
Thanks guys i decided to keep the 80hp merc I have now. I figured why mess with a good thing. I finally goy my 1983 80hp running good & I now know the motor inside & out thanks to this board & especially tony outboard. It would have been nice to have more power but it may not have paid off in the long run.