Lower Unit or Linkage Johnson 150xp

rlowhorn

Seaman Apprentice
Joined
Aug 26, 2006
Messages
48
I purchased my boat a few months ago. It is a older Stratos (1989 I think) and has a Johnson 150 xp. The boat runs really good, once you get it there. When I start the motor, and it takes a while for it to warm up, it goes into reverse smoothly but not true with forward. When I shift into forward there is initially nothing. It I shift back into reverse it seems to help it go into forward but not always. Eventually it will go into forward but sometimes it will then jump out. Once I get it into forward and moving it runs really good. What are the possibilities? Someone told me it could just be an adjustment on linkage. I am about to change the lower unit oil for season. Ideas on what I should look for and thoughts on what the problems might be. Also, thoughts on why the motor is so hard to get warmed up would be nice. If linkage can somone direct me to thoughts on linkage adjustment process.
 

Joe Reeves

Supreme Mariner
Joined
Feb 24, 2002
Messages
13,262
Re: Lower Unit or Linkage Johnson 150xp

Possibly the problem is simply that the shift cable is out of adjustment, and if so.......

(Centering Shift Cable)
(J. Reeves)

When all is as it should be, the proper method to adjust the shift cable is to disconnect the cable from the engine. Move the shift linkage on the engine to find the center of the play in neutral, and when found, leave it centered.

Now, grab the end of the shift cable sleeve, push and pull it to find the center of the play there, and center that play.

Adjust the trunion on the threaded portion of the shift cable so that the centered play of the cable lines up with the centered play of the engine's shift linkage. Install and lock the shift cable with the retaining clamp in that position. That's it.

If this is not the cause of the problem, then I would suspect that the lower unit shift rod may be out of adjustment. I don't have the 1989 V6 150hp measurement but it may be the same as the 79/86 V6 as below.

1979 thru 1986 - All V/6 Crossflow models = (L) 22-1/16" - - (XL) 27-1/16" plus/minus 1/32". Have shift rod in neutral.

If the measurement is different, another member will post the correction I'm sure. This is a common problem whereas one would have the lower unit off for some repair and turn the rod out of its critical adjustment. The measurement is taken in neutral, from the top surface of the lower unit housing to the center of the shift rod hole.

Another cause but unlikely is that the adjustable trunion of the shift cable is not clamped down in the trunion barrel (jumping out etc), it happens.
 

emdsapmgr

Supreme Mariner
Joined
Dec 9, 2005
Messages
11,551
Re: Lower Unit or Linkage Johnson 150xp

Follow Joe's suggested steps. My 1990 factory manual confirms the shift rod height at the 22 1/16" height, so your 89 should be that exact measurement also. If the water pump impeller was recently changed, it is possible that the shift rod height may have be altered somewhat. If the change was minor, it may be adjustable in the linkage inside the cowling. It is possible that you may need to service the themostats in both heads. If one of them (or both) stick in the open position, it will cause the engine to run cold. When you are in there, have a look at the nylon pressure relief valves also. Make sure they are not heat-deformed or they won't work correctly. That engine should idle in the 143-155 degree range. (unless you are in cold water.)
 
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