88 Johnson 150 GT vro

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Matt S

Seaman
Joined
Dec 26, 2006
Messages
71
Hi there, and thanks in advance for all of the wonderful information here. I'm looking to purchase an 88 spyder that appears to be in great shape, the interior and trailer look almost showroom and they're asking $6500. It seems a little steep but the condition is really great.

My question is on the GT150 and it's longevity. The boat is at a broker (owner traded it in) so I'm trying to get the history. The motor is the main concern of my purchase and I've already haggled in a free water pump and plugs, and possibly a new oil/fuel pump and a carb cleaning for parts at cost and cheap labor.

Are these motors durable otherwise? I've read the debate about deleting oil injection and I'd rather keep it (hate figuring mixed gas), as well as some stator problems. Any good checks or other services to consider before I buy?
Again, many thanks!
 
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Dhadley

Supreme Mariner
Joined
Feb 4, 2001
Messages
16,978
Re: 88 Johnson 150 GT vro

The OMC crossflows were a decent design although old technology and the motor will last a very long time if properly set up and maintained. Sounds like you've already taken care of the important stuff (perhaps a compression check should be added). If they replace the VRO pump (if it's still the old pump) it'll be the newest OMS pump. A good move. Personally I have the oil injection on all my motors and love it.
 
M

Matt S

Seaman
Joined
Dec 26, 2006
Messages
71
Re: 88 Johnson 150 GT vro

Dhadley said:
The OMC crossflows were a decent design although old technology and the motor will last a very long time if properly set up and maintained. Sounds like you've already taken care of the important stuff (perhaps a compression check should be added). If they replace the VRO pump (if it's still the old pump) it'll be the newest OMS pump. A good move. Personally I have the oil injection on all my motors and love it.
Click to expand...


I was wondering if it was a crossflow or not. Do you know of any online sources of more information such as cid, weight, powerband, general specifications?
Thanks again.
 
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Dhadley

Supreme Mariner
Joined
Feb 4, 2001
Messages
16,978
Re: 88 Johnson 150 GT vro

It's 149 cid, 2.5 liters, 2500cc, 380-385 lbs, 3.500" std bore and will live the longest if it's set up at 5800-6000 rpm with an average load. Assuming it's still stock (as produced) use Champion plugs only, 87 octane and good TCW-III oil.
 
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DJ

Guest
Re: 88 Johnson 150 GT vro

Matt S,

Dhadley is, by far, one of the most qualified and respected experts on OMC engines. Heed his advice.
 
rickdb1boat

rickdb1boat

Supreme Mariner
Joined
Jan 23, 2002
Messages
11,195
Re: 88 Johnson 150 GT vro

Dhadley is, by far, one of the most qualified and respected experts on OMC engines. Heed his advice.
Click to expand...

I will certainly second that.........
 
M

Matt S

Seaman
Joined
Dec 26, 2006
Messages
71
Re: 88 Johnson 150 GT vro

Thanks again all. I can't get a test drive before buying so I'm not sure as to the prop, but it appears to be the stock one. The spyder is a light, low profile/draft boat so unless it's over propped I would assume it peaks in that range.

They did say "compression is good" but couldn't give me numbers; which I will make them do. If I read right, anything over 100psi (+/- 5% per cylinder) is pretty good.
I'm a gearhead, but I've never gotten into 2 strokes and outboards so I again thank you for your advice.
 
D

Dhadley

Supreme Mariner
Joined
Feb 4, 2001
Messages
16,978
Re: 88 Johnson 150 GT vro

The compression needs to be no more than 15 lbs different from high to low, regardless of the numbers. And if one side is lower than the other, don't panic. There amy be a reason. We look at consistancy on each side and then overall.

Don't assume anything about the rig until you test it. If the r's are low, don't start changing props right away. Dropping pitch is always the last resort to gaining rpms. There's a lot more to set up than just props.

BTW -- DW and Rick are some of the best here too. Thanks guys!
 
M

Matt S

Seaman
Joined
Dec 26, 2006
Messages
71
Re: 88 Johnson 150 GT vro

Well being quite chilly here in the PNW I probably won't get to testing it out until april or may. I would like to get a service manual if I end up buying it. I am only finding SELOC as the printer for these, is there a better source? I would like to get a factory approved manual as opposed to the equiv. of a Chiltons or Haynes if you know what I mean.

Given the right manual, is the VRO pump easily done by someone who's never looked under the cowl at an outboard (except maybe to find out why the rope came off heh)? The fuel and oil pump is "all in one" right? My years of engine building are all automotive related.

I'd rather do any work myself to save on labor especially since I'll have some time before I can use it.
You guys are all awesome!
 
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