Tohatsu 90HP lower unit linkage issue

[clubchuck]

I purchased a 1990 Tohatsu 90A that has a frozen lower unit. I have tried to remove it but cannot get shift linkage loose. I have tried to access the linkage under the powerhead but the oil tank is in the way and I cannot get it out due to the sensor wires being too short. I have attempted to access the shift connector down near the cavitation plate but I cannot shift the engine with the lower unit frozen so I cannot get the the rolled pins to knock them out. Any ideas how to proceed?

 

[pvanv]

Re: Tohatsu 90HP lower unit linkage issue

Are you sure that the linkage is holding the LU? You may be corroded-in to the exhaust housing. The correct way to disengage the shift rod is to drive out the lower roll pin at the brass connector. If the lower rod is frozen in place because the LU is full of rust, etc., you should still be able to get to the connector after you unbolt the LU, and allow the shift lever and rod to move with the LU. On the other hand, if you are stuck in Fwd., you might not be able to get the LU down (but the coupler would be accessible), so I'm not sure of the exact problem you're having with disassembly. Have you pulled out the prop shaft housing to clear any junk inside the LU housing? If you want to remove the oil bottle, you first disconnect the sender wires, and then unbolt it. Check in your Factory service manual (available from any dealer including me) for details on removing the oil tank and dropping the LU.

 

[clubchuck]

Re: Tohatsu 90HP lower unit linkage issue

Once I unbolted the lu, it dropped about 1/2 inch so I don't think the exhaust is holding it, but trying to get to the rolled pins in the shifter rod is difficult. I wondered about pulling out the prop shaft (since it was frozen and already pushed out about 1/2 inch) but was not sure if the drive shaft had to be removed first. It seems to be seized in gear so shifting is out of the question. I will try to get to the rolled pins again. The only reason to remove the oil bottle is to get to the linkage pin under the powerhead (which I would prefer not to do) so I will try the coupler. Apparently this engine has been around some salt, as I am also replacing the shock mounts on the intermediate shaft and the bolts are seized in the housing.... PB Blaster and time are working on it..... Thanks for the info.

 

[pvanv]

Re: Tohatsu 90HP lower unit linkage issue

You could really benefit from knowing how the unit operates. Not to sound like a "broken record", but having the Factory service manual by your side would be a big help. You can pull the prop shaft without doing anything with the driveshaft. The lower cam rod can be pulled out of the LU after you release the bushing that holds it in. That may be accessible in that 1/2" gap where the LU came down. From what you describe, however, odds are that the entire LU is trash. If it had frozen water in it (enough to push the prop shaft housing out), there is probably precious little to salvage in there. It may very well be a casting full of rust. It should be possible for you to pull the cam rod up and out of the LU as long as it isn't captured in a pile of rusty junk.

 

[clubchuck]

Re: Tohatsu 90HP lower unit linkage issue

I think you might be right, probably junk. I have a line on another LU. Broken records are OK, I really need to get a Manual too. Thanks