I recently purchased a used 1991 yamaha 90 hp outboard motor. I ran the motor for 30+ minutes on the ears with no problems. After I put it in the water it ran for about 5 minutes before the high temp alarm went off. I checked external cylinder head and exhaust cover temps and they were approximately 195 degrees. After returning to the house, I pulled the cylinder head cover and cylinder head and found alot of corrosion in the water passages. This has been cleaned and the head has no warpage so I'm good there. I started to pull the exhaust cover but several of the bolts are seized and I am afraid of snapping a bolt head.
So first question, what is the best method for removing stubborn bolts?
The other thing I want to do is replace the waterpump, I have a seloc marine manual that discusses pulling the prop etc to disconnect the shift linkage. This is obviously incorrect because the linkage is all the way forward under the lowest carb. After reading several posts on here I believe it is a splined shaft that should just come apart. I have removed all the bolts from the lower unit to the intermediate including the one under the trim tab. The lower unit refuses to come off the intermediate housing. By gently prying I can get the front of the lower unit to come loose but the rear of the unit refuses to budge even by tapping with wood block and hammer.
The previous owner obviously ran this motor in salt or brackish water and didn't bother rinsing afterwards so Iim afraid the guide pins may be corroded in place. I have soaked everything in PB blaster for about a week now to no avail.
I have torn down and rebuilt both Johnson and Evinrude OB's and have never run into this magnitude of problems for something that should be simple. Any help would be appreciated.
So first question, what is the best method for removing stubborn bolts?
The other thing I want to do is replace the waterpump, I have a seloc marine manual that discusses pulling the prop etc to disconnect the shift linkage. This is obviously incorrect because the linkage is all the way forward under the lowest carb. After reading several posts on here I believe it is a splined shaft that should just come apart. I have removed all the bolts from the lower unit to the intermediate including the one under the trim tab. The lower unit refuses to come off the intermediate housing. By gently prying I can get the front of the lower unit to come loose but the rear of the unit refuses to budge even by tapping with wood block and hammer.
The previous owner obviously ran this motor in salt or brackish water and didn't bother rinsing afterwards so Iim afraid the guide pins may be corroded in place. I have soaked everything in PB blaster for about a week now to no avail.
I have torn down and rebuilt both Johnson and Evinrude OB's and have never run into this magnitude of problems for something that should be simple. Any help would be appreciated.