I have a 1998 Cobalt 25ls boat with a volvo-penta 7.4gi engine and a dp outdrive. The boat only has about 320 hours on it. I am having a problem with my trim. I only have one trim control on the throttle. I can trim the outdrive up and down on the trailer with out a problem. If the boat is in the water and i am going slow, 1/4 throttle or less i can trim up and down without a problem. If i am driving and the throttle is more than 1/4 throttle, i cannot trim up. I can however trim down. If i stop the boat and trim up 1/2 way and drive i can trim down but cant trim back up unless i stop. If the boat is on the trailer and the motor is running and i put the boat in forward at about 1/2 throttle or so i can trim up and down without a problem. I tried to listen to the trim motor when driving at more than 1/4 throttle and it sounds like the motor is straining when i try to trim up. It sounds like it does when the boat is on the trailer and i trim up and the outdrive reaches the full up position. Do you think it is a worn trim motor? Could it be a valve body or cylinder problem? I checked the reservior and it is full. Thanks in advance for your help.
