I have a 1988 Johnson GT150 and want to know what the compression numbers should be. I did a test with a buddies gauge and and I got about 82-85 on all cylinders. does wthat sound right? I like the fact they are all close but it sounds a little low????
The model number is J150stlcca
When was the last time you did a decarb on it? Compression testers vary by manufacturer but you are right, they are very close in the reading. Not too bad for 24 year old motor.
I have not done one, should I? The oil is mixed as the oil injection was undone upon installation per suggestion of the guy that put the motor on. I bought this motor used when my Johnson 115 blew on me. I am in the process of trying to sell it and one of the potential buyers wanted to know what it should be.
thanks
don
A decarb should be part of the yearly maintenance, but in your case if it has never been done I would do it using Seafoam mixed in a portable gas tank if you have one. Doing it this way will be easier on your engine. Most 150's of that vintage I see are in the 90-100 PSI range using my tester. So you aren't that far off.
Thanks Fred, I appreciate your advice. I picked up a 98 181 a couple months ago and it has a Johnson 150 faststrike. I do not know much of the history so I guess I should do the same with that one?
That would be a can of seafoam in 5 gal can and run off of that? till empty?
I did run a can of seafoam thru the new boat on the first tank that I ran.
Yep that will do it. Add about 16 oz of oil to the tank.
BOAT IS SOLD!!!! My 98 champ 181 cost me 4600. I have put some money in to fix it up for sure seats, carpet, etc. Sold my 89 tracker for 4500. For 100 bucks I think I got a pretty good upgrade. thanks for all the help guys.......
Reply With Quote