Need advice on Johnson GT150V6 1986 Model

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Saperry

Petty Officer 3rd Class
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Nov 13, 2001
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Is this motor worth rebuilding? Can I do it my self? (I have rebuilt a couple dozen car motors) How much should the parts cost.
 
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Witchammer

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Re: Need advice on Johnson GT150V6 1986 Model

Depends if you need 6 pistons or just a few. If you need 6 get Wisco they come with rings etc and it is a forged piston unlike the OMC which are not. You might have to sleave a cyld or 2. Pistons about 111.00 each cyl sleave about 150.00 each.If crank is bad that can run 350.00+ for a used one. So the cost can vary depends on how bad its blowed if its bad can cost quit a bit. I work for a boat dealer abd have a 1991 Johnson 150 for 2800.00 with 30 day warranty. I can also get reman powerheads for about 3800.00 with a 15 month warranty. So theres a lot to look at if you rebuild yourself 111.00 x 6 pistons 117.00 crank 350.00? sleave 2x 150.00- 300.00? gaskets 75.00? your time 100.00 you should be able to get the parts & 2 sleaves if needed for about 850.00 depend on if crank is needed. So lets say 1000.00 to do it youself and it blowes up on the 3RD tank of gas. My advice is find a good used motor and trade what you got in on it your lower unit is worth at least 600.00.Or get a remaned powerhead with good warranty. Hope I made since with this.
 
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Witchammer

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Re: Need advice on Johnson GT150V6 1986 Model

Sorry I mean 112.00 x 6=672.00 + 350.00 crank?+ 300.00 sleave?+75.00 gaskets = 1397.00???? and that depends on a lot of ifs
 
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Witchammer

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Re: Need advice on Johnson GT150V6 1986 Model

I also have a very good 1986 Merc 200 with controls 124 psi on all cyd. About 175 hrs on it not a scratch on cowl. 2000.<br />00 runs great taken good care of one owner me.
 
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Dhadley

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Re: Need advice on Johnson GT150V6 1986 Model

Let's start with the basics. What is wrong with the motor that it has to be rebuilt? <br /><br />Let us know!
 
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Saperry

Petty Officer 3rd Class
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Re: Need advice on Johnson GT150V6 1986 Model

the #5 Cyl is scored (you can see it throught plug hole) Compression 1-6 is 102, 102, 106, 103, 97, 100 The boat shop I had look at it sais blow by test shows 36% on # 5 ad 25% on Others.
 
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Saperry

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Re: Need advice on Johnson GT150V6 1986 Model

This is a boat I recieved to settle a debt of 1500.00. I knew it might need some motor work but now the guy at the boat shop says it needs an overhaul and a new transom. I think i just got ****ed. I was hoping to get some use out of the boat in the spring.
 
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Saperry

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Re: Need advice on Johnson GT150V6 1986 Model

Anyone have thougths?
 
clanton

clanton

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Re: Need advice on Johnson GT150V6 1986 Model

The numbers are in the spec range called for in service manual, I would clean carbs, bypass VRO2, a can of engine tuner and go boating.
 
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steve forsythe

Petty Officer 1st Class
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Re: Need advice on Johnson GT150V6 1986 Model

In my experince any time you collect anything on a debt....you didnt get sc.ewed! unless he was offering cash or the boat! :D
 
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Witchammer

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Re: Need advice on Johnson GT150V6 1986 Model

102, 102, 106, 103, 97, 100 Is not bad I yhought it was blowed. If this is the case powertune or Yamaha ring free might bring those #### up a little and will bring some life back into it. At 1500.00 you are not screwed powertune or Yamaha ringfree and premix your oil and run it till it does blow. You might get a lot of years out of it again I thought it was blowed change your waterpump once a year also change your lower unit lube 2 times a year better safe than sorry.
 
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Saperry

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Re: Need advice on Johnson GT150V6 1986 Model

So you don't think it needs a rebuild? Even with visable damage to #5 cyl.... I am going to pull the moter off to work on the transom<br />and I was hoping toe get away with new rings untill I saw the inside of #5. Is it ok to replace only one cyl.... Can it be bored over size w/out boring all six. Also how about transom replacement? The boat looks great but the transom flexes quite a bit. The boat is a 1985 Skeeter SF180 Regency Fish/Ski. If I "run it till it blows" will the rebuild cost more then?
 
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dick

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Re: Need advice on Johnson GT150V6 1986 Model

Yes , on outboards you can bore one hole and hone the others .The comp. on this engine isn't that bad , run some powertune through the motor and try it out.And also some minor scoring in outboards is normal.
 
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Saperry

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Re: Need advice on Johnson GT150V6 1986 Model

Is blow by measured as a factor of compression loss or is it a different test.<br />The guy at the boat shop seemed to indicate it was a different test and that 36% on #5 was really bad and 25% on others was not much better. Maybe he was trying to sell an overhaul job. He pretty much said the motor was worthless. It does start and run. I have never had it in the lake. Should I put it in the water and see what it does?
 
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Saperry

Petty Officer 3rd Class
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Re: Need advice on Johnson GT150V6 1986 Model

Also if I am going to buy a manual for this moter. Clymer or Solec? Which is better ia there a difference?
 
S

Saperry

Petty Officer 3rd Class
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Re: Need advice on Johnson GT150V6 1986 Model

Thanks for all the advice. I am still unsure of what to do. I am going to take the boat to the lake this weekend and see how it does. Where can I get this "powertune"? What is the best procedure for using it? Still unsure of the difference between compression loss and blow by. I suppose you can loose compression through the valves and or heads and it would not be considered blowby. How can you say this cyl has 25% and that has 36% unless you are looking at it as a factor of compression. I have a good set of compression gauges so I can do some checking on my own to find out. Do you check an outboard the same as a car? Spin on starter at WOT with ign. disabled. Any advice from people familar with this outboard would be great. Thanks again. :confused:
 
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norman158

Petty Officer 1st Class
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Jun 29, 2001
Messages
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Re: Need advice on Johnson GT150V6 1986 Model

sounds like the guy at the shop also ran a leak down test. this is done by injecting air into the cyls and mesuring the leakage or blow by past the rings.
 
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Saperry

Petty Officer 3rd Class
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Nov 13, 2001
Messages
99
Re: Need advice on Johnson GT150V6 1986 Model

Just bought clymer manual and can of OMC Engine Tune. Should I use the tune at home with ear muffs ank take it to the lake the next day? (Instructions say leave it in for 3-16hrs)Or go to the lake and use at the ramp then picinic for 3hrs? How long should I run the moter after?
 
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