Re: 1989 Johnson 110 thermostat replacement
On the early bubble backs, if you lower the bottom cowling, it will move enough to give clearance to work on the stats/housing. The later ones like yours, don't seem to move quite as much. Even still, it's best to unbolt it for added working clearance. It's flatrate of nearly 3 hours to remove and replace the powerhead. Most mechanics can get the job done in much less time, so they rarely get removed. Still, you will expect some skinned knuckles. I've heard of some that will put the assembly together with thread through the bolt holes, then cut the thread prior to torquing the three bolts. Others have drilled holes in the back of the lower cowling for added wrench clearance. As boobie says, there are a number of threads in this form on the subject. A 1/4" drive set with a swivel knuckle is a good tool set for this job.