Purchase of early 80's Black Max 150

[Chris1956]

I have been shopping for a used motor. The local boat guy took in an early eighties 150HP V-6 Merc. Looks to be suffereing from lots of neglect, but it is not seized. It has the clam shell cowling and oil injection, but I haven't been able to scrape the crud off it to get the serial number.

Since I think I can get it for small $, I am tempted to buy it. I will guess this is the motor with the oil injection that fails unexpectedly (plastic gear??). Are there any other areas of weakness in thse motors? I must admit that I do not see any of these still in use.I was thinking I could check compression and spark, prior to any sale. I would think the carbs are in need of rebuild and the waterpump as well.

Comments....

 

[tashasdaddy]

Re: Purchase of early 80's Black Max 150

and disable the auto oiler. and premix

 

[CATransplant]

Re: Purchase of early 80's Black Max 150

Yah, check the compression and spark, for sure. Then think twice about buying it. After you do that, think twice again.

Sounds like an outboard that has had poor maintenance, overall. You might get a nice surprise, but it's more likely that the surprise won't be so nice, I'm thinking.

 

[Chris1956]

Re: Purchase of early 80's Black Max 150

But CA, it woukd look so good on my speedboat....

Seriously, if I think about the likely problems with this motor, I get that sinking feeling in my stomach.

 

[CATransplant]

Re: Purchase of early 80's Black Max 150

But CA, it woukd look so good on my speedboat....

Seriously, if I think about the likely problems with this motor, I get that sinking feeling in my stomach.

If I were you, I'd listen to that stomach. My next door neighbor has one of those outboards, and he spends most of his time with its hood off, fixing whatever broke the last time he took the boat out.

Most of the problems have had to do with the oil injection system, but he refuses to just premix and keeps spending money on bits and pieces. I heard him yesterday running the thing on muffs...it was missing badly. He's replaced coils. He's replaced the ignition module. He's spent more money on that engine than I have in my entire rig, and he just keeps doing it again and again.

I have nothing against Mercury Outboards, but that engine appears to be a turkey...at least as it ages. Too many plastic parts, and age doesn't seem to be helping.

 

[studlymandingo]

Re: Purchase of early 80's Black Max 150

I have nothing against Mercury Outboards, but that engine appears to be a turkey...at least as it ages. Too many plastic parts, and age doesn't seem to be helping.

I have an '86 150. I replaced the stator last year (it was the original) and I have replaced the wires from the original switchboxes to the original coils. Runs great and the original oil injection system works.​

 

[phatmanmike]

Re: Purchase of early 80's Black Max 150

there is nothing in the world at all wrong with a mercury v6 of this vintage. its the longest running model of any manufacture. they made these same models for the late 1970's all the way well up to and into the 90's. never changed a thing, never had to!

ive owned many of them including my current twin 135's and my 2.5L 200hp

this 150 you speak of is most likely the 2.0L model. all parts interchange with the 2.0, 2.4 and 2.5L models except carbs and major internals, of which even some of those interchange. so you will have an easy time finding both parts and service cause these motors are everywhere!

dont listen to the naysayers. clean 'er off, check compression, check spark and go from there. these were and still are excellent motors!

 

[woodchuck]

Re: Purchase of early 80's Black Max 150

I have a 1984 merc 150. I purchased boat and motor used in 1988, sence then I have had the carbs rebuilt [1989], replaced theTT last year. replaced the hose on the choke selanoid and replace the impeller a few times. Changed sparkplugs a few times. I run 91 octane fuel. This motor has not failed me in the 19 years that I have had it and it still is running strong.
Woodchuck

 

[BF]

Re: Purchase of early 80's Black Max 150

I have an early '80's version that's still going strong on my ski boat (82 I think?)... pre-oil injection... it has been very good to me. Changed a stator on it years ago. One somewhat weak thing on these motors is the driveshaft. They used a fairly thin one with a preload pin on the top. I forget what year the change over was (84 ?)... then they went to beefier ones. I broke the driveshaft on mine a few years ago at the level of the upper bearing. I've since realized that my poor habit of not having the motor tilted completely down when filling the LU probably meant I was under-filling the lower unit by a few ounces. (I had to cut a hole in the floor of the boathouse to remedy that). Anyway that may have contributed to the failure (underoiling of the upper driveshaft bearing, which got hot and failed and took out the driveshaft). I redid the lower unit myself, and it's been fine since then... not a major flaw, but just make sure you fill it completely with oil.

So I agree with above... compression test before you buy, also check the lower unit oil for water and the magnet for filings. If all is OK, then make a deal and expect to do some carb cleaning and impeller before you run it. Can you start it before you buy?

good luck.

 

[Chris1956]

Re: Purchase of early 80's Black Max 150

Thanks to all that posted. Your experiences are useful input. BF, I pegged this motor as a '79-early 80s since it had the black/white red stripe cowling like the '79 inlines. It does have the oil injection. Is it possible I think it is older than it is?

I have started looking on e-bay, and have found some local sellers of O/Bs. It think local is the way to go, so you can really see it. I may end up with this motor yet, since I need to see this boat guy on another matter. If so I will inspect the engine wiring, compression, spark and LU. I will try to see if I can cycle thru the PTT function, spin the starter etc. I expect the carbs may need rebuild and a new pump impeller, but would like to keep it at that.

 

[BF]

Re: Purchase of early 80's Black Max 150

Like I said, I forget the year of mine... maybe an '80? It does not and never did have oil injection. I know that very shortly after, they did. (maybe even the next model year). Mine has the blue striping on the sides. I'll see if I can add a pict....