ok, I just bought this motor (1990 mercury black max 135hp 0C199906) and it runs great, it is mounted on a 1989 procraft 1660v fiberglass boat. the only problem i am having is with the steering. at low speeds it is very hard to steer both to the left and right, it does not like to go in a straight line. at high speed it pulls just a little to the right but is a lot less hard to turn the steering wheel. any ideas as to what I can fix with this? Is it possible to install power steering with this rig? I have greesed the one fitting that i found that is related to the steering parts. but I do not know what else to check. thank you for any input about this.

More than likely your steering cable is binding due to dried up grease inside of it.  Don't bother asking about lubing it, it's a waste of time on something that old.  Besides, you don't want a temporary fix on that part of a boats operation.  Steering cables in the condition yours are in have been known to break while the boat is underway at speed.

Not knowing what you've got, I'd suggest either a Rotary or Rack & Pinion NFB system from Teleflex or, if you're interested in "power steering", a hydraulic system from the same company.

Know that a hydraulic system is probably going to cost at least 3 times the cost of a standard steering system.

Replace the steering cable(s) and you will be able to steer it with a finger. Cost is a little above 100.00 for a 12-14ft cable. They are easy to change out.

Likely, as said, it is the cable but you might not be getting the boat trimmed out properly at speed. My rig is similar but an 18' with a 150. Improperly trimmed it pulls a bit. Also your trim tab might need a slight adjustment.

thanks for the info guys. Ive made an appointment to get it looked at next week. It got a little scary on the water so I better let a mechanic look at it before there is more to fix. Ill post what was wrong incase any one else has this problem as soon as I find out. cables is a likely cause but maybe the whole system needs replaced at this age.