89 Johnson 150 compression, What it is? 89 Johnson 150 compression, What it is?
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    89 Johnson 150 compression, What it is?
from Sparky (  
5/17/1999 6:29:00 PM


 I am currently having a problem with my motor. The first three times I run it at WOT it has an intermittant feeling of like a gust of wind is momentarily holding the boat back. The more the motor runs during the day the problem totally disappears. The compression is as follows, Top two cyl. 74 - middle two cyl. 96 - bottom two cyl. 98 . What should the compression be? Is the motor junk? The repair guy told me anything over 15# difference between cyl. and the motor needs rebuilt.

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   Im from Pennsylvania, not Alabama from Sparky (  5/17/1999 6:31:00 PM
 No msg
   150GT Compression from CGGarner (  5/17/1999 9:00:00 PM
 I blew the power head twice on my 1990 model Johnson GT 150. My compression ran around 105 psi to 95 psi on the good cylinders. The first blown power head after three years of use had about 50 psi on the bad cylinder. The second time the bad cylinder was about 85 to 95 psi. Each time that I had a problem, I took the motor to a reputable outboard motor mechanic. I highly recommend that take it to a mechanic that you trust. It will only be a small charge for them to remove the heads. In my case I had a bad carbon problems on the piston rings that caused the failure. Your case could be totally different and may not even be close to my experience.

Email me, if you have any other questions.

   GT-150 Compression from Bigfish (  5/18/1999 8:26:00 AM
 Sparky, You've probably seen some of my posts on the 1989 GT-150 (#21407, #21916). Besides some of the symptoms I posted in these, when I was running full throttle, I would get the same type of "gust of wind" feeling. I would describe it like the prop picked up some weeds, but when I stopped and checked there was nothing there. It only happened intermittently and was very frustrating because of this! It sure made sense that it was a fuel problem, but turned out to be electrical. The first place I would start would be a "trusted" mechanic. Not sure where in PA you are, but I'd give Mare a shot in Frederick Maryland. I also understand Eagle (Ken Wilson) Marine is good to. Of course, if you are planning a trip to Buggs Island, try Allens (see posts). The compression differences may be able to be corrected if due to carbon build up (have engine tune run through it). I would definately have the electrical system, fuel system gone over too. I have heard from a number of people that these are some of the better engines ever made, so hopefully you will not have the major problem you think. With all the negative publicity (and prices) I've heard about the new ones I'm quit happy with my GT (now that it is back to running). If I can be of further help post again, with any questions. Good Luck and Good Fishing! Team Jesus
   Hey Sparky from Bigfish (  5/18/1999 8:46:00 AM
 Just checked back to my previous post to try and find who I had to get back to with similar problems and found it was you. I had an appointment this Friday to have mine checked, but it didn't last that long. Where in PA are you? I'm down in Richmond, bought boat at Mare in Frederick. Brian (owner is pretty descent guy and their mechanics should be reputable). If any ways possible, I'd try Allen's, the guy is sharp, reputable and will do you right! He told me that the timer base assembly may have caused the power pack to go bad, so if one is going bad, you want to catch it before the other goes. Have you ever replaced either? Although it was a little expensive, I figured 10 years and over 600 hours with no repairs (except alternator), these things were bound to happen sooner or later. Let me know where you are at and what (if anything) I can help you with.



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