150hp black max buying advice

[Mybiggles]

Hey guys. Going to be looking at a early 80s Blackman 150 (blue\black stripes) this weekend to replace my 115gp top. The motor is extremely cheap and the guy selling it doesn't seem to know much about he just says it has "start motor problems" and isn't answering many questions about it. He's agreed to let me run some tests before purchase.

Questions I have are

Anything I should keep and eye out for other then obvious damage?

Will the starter from my 82 tower of power 115hp work to do a compression test if I can't get the original starter going? If not is there any way I can do a compression test by hand? Thinking maybe a drill on the crankshaft or wrapping a rope around the flywheel and pulling it over by hand?

If I can get it to turn over and test compression what numbers should I be looking for? I know an even spread is more important then peak numbers but what's like the lowest numbers id want for it to run half decent?

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[QBhoy]

Hi
i have a late 80’s black max 2.0 150. Acceptable compression with a known good tester would in my opinion be above 105 psi...but preferred to be 110-120ish in a perfect world.
If the plugs are out and you are careful enough, I don’t see a reason why you couldn’t turn it over with a gun on the top flywheel nut. Bare in mind the engine will be cold and not at its best result when doing this.
best of luck !

 

[achris]

With the starter motor gone and you unable to run the engine, or do a compression test, I'd be walking away! I would almost bet my house that the starter motor is gone because the seller doesn't want anyone trying to get it running before he has their money in his hot little mitt.

If you do 'pays your money, takes your chances', check the gearbox oil for water and age. If it's dead fresh, be skeptical. Also check things like the internal rubber mounts for slackness, check the wiring harness for bad wires, and if you can get a rope around the flywheel, check for spark on all 6 cylinders. Prime the fuel system and check for leaks.

Chris.........

 

[Dukedog]

really, really, really cheap?.. takin' a big chance at any price with that age if not runnin'..its "first generation" motor.. unique block/head design that really sucks.. good luck with it... be sure ta test/ask 'bout tilt/trim?.. have tha pump/hoses?

 

[jimmbo]

The fact that the engine has a Whale Tail on it tells me it must be a dog, the 150 was a Torquey Motor, both Crank(81) and Prop(82 - 83) rated versions, which had that kind of Decal on the Cowl.
The 1981 Black Maxes did not have the Little Black Max Emblem on the Lower Decal on Engine Cowl.

 

[achris]

The fact that the engine has a Whale Tail on it tells me it must be a dog, ....

Or that the PO was an idiot who didn't have the first clue about how to set up an engine/prop combination. Or was someone who just wanted to be 'fashionable'.... :facepalm:

Lots of reasons to put those godawful things on, none good.

Chris......

 

[jimmbo]

Or that the PO was an idiot who didn't have the first clue about how to set up an engine/prop combination. Or was someone who just wanted to be 'fashionable'.... :facepalm:

Lots of reasons to put those godawful things on, none good.

Chris......

Can't argue with you there

 

[Chris1956]

I would crosscheck the starter number from your TOP, on an aftermarket starter, like ARCO. I always thought the TOP starter would fit the V6, but never actually tried it.

Don't worry about the whale tail. You can always take it off. Check the gearcase for water, and get a compression check. The rest is fixable, if you are handy. Those V6 motor usually have ADI ignition and 3 two barrel carbs.

 

[Faztbullet]

Earlier V-6 used different starter and Bendix ...IMO would walk as too old and to many unanswered question(compression,controll box,trim pump)

 

[Mybiggles]

So I went and looked at it last night. Starter would spin but not pop up to engage the flywheel. When I was right about to give up on trying to pull start for compression the owner of the shop showed up and pulled a spare starter out of a pile of parts. Wired it up and compression was 105 on one cylinder and between 115 and 120 on the others. He runs an outboard repair shop and said he was given the outboard by a customer and didn't have time or cared to deal with it and just wanted to make a quick buck. Looks like it hasn't been ran in a few years so hoping the 1 cylinder comes up a bit. Regardless it's got better numbers then my tower of power so I think it's a fairly safe upgrade.

I didn't check the gearcase oil but there wasn't any physical damage to the leg, the prop shaft spun smoothly and felt tight in its housing. Shifting into gear the shaft would spin with the flywheel.
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im getting it for $300cad so it's a fairly safe bet. I can probably flip my 115 tower of power for around $1000 which would fund a new prop,carb rebuilds, impeller and any electrical it needs with a bit left over.

​​​​​​gonna get it home and on a stand and go through it before I throw it on my boat.

It has the power trim pump and lines but I didn't bother to test it. I have a power trim plate on my boat so it's not the end of the world if I can't get it working.

 

[Faztbullet]

When you get it going...don't be disappointed by its performance as its only about 130HP at prop

 

[Mybiggles]

Thought they rated them at the prop on those years?

 

[racerone]

At $300 it is like buying a lottery ticket.---Might be a good deal or a parts motor for your next purchase.

 

[Mybiggles]

Compression is decent. I'll get it running. Looks like the coils and switch boxes are the same as my tower of power. I've already replaced most of the electrical on it I'll just swap over what's compatible. I'm sure it'll be fine. If not I'll just sell it for what I got into it.

Only thing that sucks is 6 carbs to potentially rebuild and those kits don't look very cheap

 

[jimmbo]

Mercury started Prop Rating their 6 cylinder engines in 1982. 81 was still Crank Rated

 

[Dukedog]

you're motor has three carbs.. should be WH series unless its '76/'77.. they probably only need a good cleaning and new gaskets.. all WH series use same gaskets, needle and seats... think tha kits 'bout 30 bucks now cause they added needle and seats to what use ta be 6 dollar gasket kit... only thing that needs ta be looked at with 'em is if floats are fuel soaked.. new floats may be a problem ta source?

wh kit part number:

Mfg Part #: 1395-6452

 

[achris]

The other thing to look very closely at it if the carbs have throttle shaft/housing wear. If they do, you need to fit that. Last V6 I rebuilt was because it had detonated 2 pistons because of worn throttle shafts, which allows more air in and runs those cylinders lean.

Yes, the coils and switch boxes are the same. If you find an 'idle stabilizer' on that engine, ditch it!

You have a Merc service manual for it? If you post the engine serial number we can give you a year, and I may have a service manual. By the engine covers decals it looks early 80s.

Chris....

 

[Mybiggles]

Got it home today and on a stand. I looked up the serial number it looks like an 82. It has a newer stator and switch boxes on it. Carbs look like they are clogged as it won't fire with fuel hooked up but it runs when I spray fuel in manually! With a bit of maintenance it looks like it's going to be a good runner!

Trim pump just shoots sparks when I hook the leads directly to my battery so it'll need a rebuild or replace. What's the best bet for those?is there cheap aftermarket pumps?