1987 150 Johnson VRO

[BMack1]

I purchased a 1987 18ft BW Outrage with a 150 Johnson (560hours) about a year ago. The engine runs great, I have put on another 100 hours. I have done the basic maintenance; spark plugs, waterpump, lower unit gear lube, and thermostats (original). Also, I replaced the warning horn in the binacle control and disconnected the VRO.<br /><br />Questions<br /><br />1. Should I use QL16V spark plugs which came with the engine?<br /><br />2. The mechanic who replaced the waterpump and thermostats also measured the compression. He claimed:<br /> 105 95<br /> 100 80<br /> 105

 

[BMack1]

Re: 1987 150 Johnson VRO

Oops, let me finish:<br /><br />2. Mechanic measured compression:<br /><br />95 105<br />80 100<br />90 105<br /><br />Would the engine run perfect if the compression was as listed? Should I worry about this or try to test the compression myself. Like I said I have put on about 100hours without a problem.<br /><br />Thanks,<br />Bob

 

[Dhadley]

Re: 1987 150 Johnson VRO

Welcome!<br /><br />Does that mean that number 5 cylinder (bottom starboard) has no compression? <br /><br />Im sure its OK, the number is just missing. The 16 is a good plug, just a tad pricey. You can use the QL77JC4 also.<br /><br />Good luck!

 

[Dhadley]

Re: 1987 150 Johnson VRO

Ah ha! You beat me to it!<br /><br />Lol!

 

[reeldutch]

Re: 1987 150 Johnson VRO

I was told that if the compression has more than<br />15 psi difference between the lowest cylinder and highest that you have bad compression.<br />you have a difference of 25 psi.<br />if i was you i would test your copression freqeuntly so you have a idea what is going on.<br /><br />good luck reeldutch

 

[rickdb1boat]

Re: 1987 150 Johnson VRO

As Dhadley said, I would use the QL77JC4's gapped at .040. They run better at that gap, rather than the more recent .030 recommendation. They will also foul less that the QL16V's.

 

[OBJ]

Re: 1987 150 Johnson VRO

Bob...give the engine a decarb job. Might help that low cylinder. Then as reeldutch suggested, keep track of the compression.

 

[Dhadley]

Re: 1987 150 Johnson VRO

Also look at the cylinder heads. there is a 6 digit part number cast in on each one. Post those numbers so we can determine if we have a matching set. If we dont that could be some of the bank to bank difference. <br /><br />A decarb job is a good idea too as OBJ suggests.

 

[BMack1]

Re: 1987 150 Johnson VRO

Thanks for the replies,<br /><br />Part # from heads 328324 and 328325<br />J150TXCUR R7499458<br /><br />I forgot to mention that I did run about 2/3 of a can of OMC tuner through the engine. Your right about the plugs they did seem to foul after about 50 hours. Cleaning them seemed to bring them back. I do have a set of the cheaper plugs for a backup. What type of compression gauge should I buy? cost? What is the basic technique to measure compression? I am not sure I trust the mechanics numbers. He managed to break off and helicoil four bolts when removing the theromstats. Although, they may have been the original thermostats.<br /><br />Thanks,<br />Bob

 

[tntwalker]

Re: 1987 150 Johnson VRO

I'll chime in only because I just bought a compression gauge last night at Advance Auto... $24.95 for the screw in type... thus allowing you to check the compression without a helper... <br /><br />I pulled the killswitch lanyard and turned the motor over 5 or 6 times for each cylinder... I'll let the pros decide if that's the preferred method or not...

 

[Dhadley]

Re: 1987 150 Johnson VRO

Thats a matching set of heads. Good.<br /><br />Taking the compression yourself is not a bad idea. Keep us posted.<br /><br />Good luck!

 

[Cricket Too]

Re: 1987 150 Johnson VRO

One thing to add to what tntwalker said, make sure you have the muffs running water to that impeller while your cranking for compression, you don't want to trash that new water pump, the rest of the procedure is exactly how I do it. Good luck.

 

[BMack1]

Re: 1987 150 Johnson VRO

Hitting tab causes problems when posting<br /><br />Here are the results:<br /><br />Warmed up engine on muffs (15min). Heads still much cooler by touch then after a 10 mile run on plane.<br /><br />Removed all plugs and pulled lanyard.<br /><br />Looking at back of engine (approx readings):<br />90 84<br />94 82<br />85 82<br /><br />How does this look considering the engine was not<br />completely at operating temp? <br /><br />I am using V gap plugs. Do these foul quicker than a standard plug? I hate to change based on the current engine performance.<br /><br />Also I need to fix the tach, what are the basic test procedures. I have access to a scope and meter.<br /><br />Thanks,<br />Bob

 

[rickdb1boat]

Re: 1987 150 Johnson VRO

Reading look fairly consistent, although a tad low overall, but OK. As far as the tach working, is/was your charging system working? If the tach is good and wired properly, most times it's the rectifier that is the cause. It also causes a no charge problem if defective. And yes, the v plugs will foul easier at low speeds and trolling than the QL77JC4's.

 

[Cricket Too]

Re: 1987 150 Johnson VRO

Looks like you have 12-14 psi. difference between some cylinders, that's right on the edge of good and bad. Anything over 15 is usually an indication of some damage, but I have seen motors run good with worse readings. I would decarb the hell out of it 2 or 3 times, make sure the carbs are running good, not too lean, maybe rebuild them cause you know they have at least 100 hrs. on them, and if all is well I would probably just run it. If it is running OK with those compression readings, which may get better with decarb, then I would run it until it starts having problems, which could be a while, then rebuild it. Good luck.

 

[BMack1]

Re: 1987 150 Johnson VRO

Thanks for the replies.<br /><br />I will buy a couple cans of engine tuner and check the compression after a few more hours.<br />I am hoping to get a couple more years out of the motor and then repower.<br /><br />As far as the charging goes, my fishfinder shows approx 12.6V when running. I try to charge the battery at home the day before using the boat. Maybe I need to reevaluate the charging system.<br /><br />One other item, the boat was kept on a lift (saltwater) 16+years. The steering arm has alot of corrosion. The steering arm I am talking about kind of looks like a wishbone. Is this a major safety issue? Have they been known to fail?<br />How much $$$ would this add to a rebuild?<br /><br />Thanks,<br />Bob