I've got a 2002 200-hp 4-stroke. I took it to a local Yamaha service center to get it serviced. I received a call from them telling me that they couldn't get the lower unit off to replace the water pump. They had tried everything, even using a torch. I brought it back to see what I can do with it. I was able to loosen the back side of the unit(where the zinc sits) but I'm having problems getting the front side loosened. I don't see any linkages that may interfer with the unit coming off. The service center told me it's corrosion that's holding it together, which I don't believe cause I don't see any salt build-up inside. I've tried the screwdriver technique but that's causing more damage to the casting. Might there be a linkage that I'm not seeing or an easier way to take the unit apart? If anyone has any new ideas, please let me know.
It's not the corrosion that you can see that creates the problem. The driveshaft must've corroded to the crankshaft. Saltwater will do that to you. That's why a 5 year old saltwater motor is a very old motor and a freshwater motor can last for decades.
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are you sure they pulled all 8 bolts? there are 3 on each side. one under the trim tab and one fwd of the tab area. its the same style case as the 3.1 l v6. that 8th bolt has bit may a tech. I have seen one that wore the oil pump drive splines and got stuck. but never seen a properly maintained motor with that problem. properly maintaned motors you can always remove the t-stats,water pump,and pressure control valves.
no tech questions by PM, they wont get answered.
you have to be trusted by the people that you lie to .
I pulled all 8 bolts, I'm not sure if they did. The back part of the lower unit is loose enough were I can see thru, I actually have a screwdriver in there, and I can't see corrosion. I also have a 1999 25hp 4-stroke engine and when I take the lower unit off, there is an oversize nut that connects the gear shaft. I'm wondering if the 200hp has something like that which I can't see. Is this a possibility?
Assuming all of the attachment bolts are out, What is most likely keeping your lower unit from comming off is a badly corroded driveshaft support bearing that will not easily let the driveshaft pass through. I had this problem. The lower unit case would not seperate at all. I was advised that it had to be wedged off. I started with putty knives, then screwdrivers, then crowbars, and finally wood block spacers with the crowbars. Yes it will mar up the mating surfaces; after the unit is off just file them smooth as best you can. After the lower uint was off, the support bearing just broke out in chunks. Clean out the bearing cavity well, it will be full of corrosion and salt. Bearing is available at Yamaha dealer, I payed $60. Grease everything with waterproof grease upon reassembly.
good luck mullet. when you get your gearbox off and everything lubed think about all the work you could have saved yourself with a gearbox removal every year. preventative maintenance is key in salt water. now might be a good time to pull the t stats etc before the bolts holding them in seize also. if you have been to the same dealer every year for a service and they havent been pulling the gearbox as a measure of regualar maintenance you should be asking some questions.