1985 Mercury 90HP in-line 6 - Recommendations

[Mscanon99]

Hi All,

I sold my last boat which had a 115 Merc in-line 4 and am thinking about picking up an older boat with a 1985 90HP in-line 6.

Any recommendation on this motor? Good, bad, issues, user reports?

Thanks

MS

 

[Laddies]

Re: 1985 Mercury 90HP in-line 6 - Recommendations

In equal condition a much better engine that the 115, 4 cyl.

 

[jevery]

Re: 1985 Mercury 90HP in-line 6 - Recommendations

I had one years back on a Mark Twain trihull, same block as the 115 and very large for a 90 HP, but I loved the look of those tall motors. Mine was bulletproof, ran it wide open for hours on end pulling slalom skiers. Smoked like the devil though as I mixed the oil a little heavy to counteract the abuse I put it through.

 

[Mscanon99]

Re: 1985 Mercury 90HP in-line 6 - Recommendations

Thanks for the notes on the motor....here is the situation.

The motor is on a 1973 AMF Slickcraft SS 160 (16 footer/closed bow). The boat is really cool, nice lines, solid floor, neat controls/dash including an electric motorized spotlight that is controlled from a small chrome joystick on the dashboard. There is an hour meter on the dash which reads 127hrs....this was set up when the motor was installed....it looks right from the motor's condition. The Merc is fresh water use, exctreamly clean. Even has a special cover on the motor and all the pinstriping/decals are perfect. The motor has Tilt/Trim.

Here is the bad...the boat, although in overall great condition slipped off the trailer a few years back and there is a repair at the very back and bottom of the stern, where the boat slipped off while underway, it dragged on the pavement. This has been repaired and looks OK, no gelcoat, just a good fiberglass job where it is smooth and appears tight. Secondly, the trailer is 35years old....it looks OK, but I am not sure I would trust it.

The guys wants 2000.00. Basically, I am buying the motor, figuring the boat/trailer arn't worth much. Does anyone have any advice on this....I was thinking 1500.00 assuming the motor checks out (spark/compression/lower unit)

Thanks for any advice.

MS

 

[rndn]

Re: 1985 Mercury 90HP in-line 6 - Recommendations

If you just want the motor, then look elsewhere. Just because the stern has been repaired and the trailer is 30 years old, does not mean they are ready for the scrap heap. If the damage to the boat was just cosmetic, then you really shouldn't worry. If it got into the structure of the transom, then the boat may not be worth anything as it all depends on who and how it was fixed.

 

[Mscanon99]

Re: 1985 Mercury 90HP in-line 6 - Recommendations

No, not just looking at the motor, I am looking at the package, wondering what the motor is worth.

If the package is 1500, and I get into trouble with the boat, whats the motor worth?

Just trying to figure out if 1500.00 is reasonable. I would guess the motor is worth 750.00 or so, but not sure.

Thanks

 

[rndn]

Re: 1985 Mercury 90HP in-line 6 - Recommendations

It's hard for someone to value a motor without knowing the history and hours. It could be worth a couple of thousand or it could only be worth $50.00. You'll have to be the judge of the value based upon what you see and hear as the motor runs. Make sure you do a compression and leak down test.

 

[tashasdaddy]

Re: 1985 Mercury 90HP in-line 6 - Recommendations

BUYING A USE MOTOR

overall condition, condition of the place you are buying it from, usually tells you how they care for things. compression 100 + psi, and within 10% of each other, good strong blue spark, no water in the lower unit oil. look for discolored paint, (sign of over heat at
one time, also scarred up bolts, as why. have them start it. if they fail to put it in a barrell or tank, or on muffs, or in the water, to start it they don't know what they are doing. best yet is to take it for a 30 min to 1 hour test run. also if remote controlled motor, the controls should come with it.

 

[Mscanon99]

Re: 1985 Mercury 90HP in-line 6 - Recommendations

OK All,

Here is the update, I like the boat, very cool design, has a vintage look and it in overall very good shape....enough with that, this is about the motor.

I Spoke with the guy, he's had it for 12 years...he purchased the boat with 8 hours on the meter...now it has 127. Its a 1985 90HP in line 6, super clean, looks brand new from the covers.

I agreed to a price with the condition it gets a checkup at a trusted marine service center. I will have all the usual checks done, compression, lower unit, oil, spark, etc...

All is good, then I ask him what his winterization routine was. He told me he sets the boat up with muffs and the hose connected to RV antifreeze and runs it out of gas....no fogging oil, just run it dry of fuel while its sucking up antifreeze. I said I've never heard of this process...he said this is how his uncle did it so he just did what he learned from family. I forgot to ask if he ever had the gear oil changed and or the impeller...I am wondering if he did.

Anyone ever here of this type of winterization? Kind of scares me, wondering if my mechanic will be able to tell if damage has begun. Do you think that if compression/lower unit pressure test and all the other checks I listed will pick up on any issues from this type of maintenance?

Thanks to all for your thoughts.

MS

 

[mickjetblue]

Re: 1985 Mercury 90HP in-line 6 - Recommendations

I had a '82 90hp Merc, and ended up selling the package for no fault of the
motor or boat. The 90hp 6 is a powerful motor with tremendous torque and
if it's running right, very smooth. At about 4300-4500 rpm, that motor hums
with a tone of perfected machinery. I miss it. Starts instantly.
Great motor, if in good shape. That's what you need to find out. Good luck!

 

[Mikehm]

Re: 1985 Mercury 90HP in-line 6 - Recommendations

I got my first boat in 1968, a new 16' Glasspar with a 90 HP Merc, and I loved that engine, had it for 8 years, and never had any problem.
Then later I got a 17' Gulf stream with a 125 HP Merc in-line 6, and had good luck and no problems with it either, and really liked it.
From 1968 to 1990 all I ever had over 40 HP was in-line 6 Merc's, and that's all I wanted.
Mike.