Expert: Jeff Grigg - 1/24/2008

Question
Hello, I have a 1996 oceanrunner 225. Tilt switch stuck in the down position an ran for hours before we heard the trim unit screaming and shut the power off. Replaced the switch. Up and down tilt and trim are ok. The problem now is that the motor will not lock down. It lifts out of the water in reverse and slams down when you let off of the throttle. Unit does not bleed down at all while up. I am a 20 year Toyota tech and do have the factory books for this unit. I was going to take the unit apart and look for any kind of stuck check vale. If you know what the problem might be you would save me alot of tinkering time. Thanks Sam

Answer
When the trim unit trims either up or down once it reaches it's limit there is a hydraulic pressure relief valve that opens and lets the fluid bypass. I would be willing to bet that it ran so long with so much pressure it is stuck open.
One thing you might want to try is to release all pressure in the system with the manual relief valve. Use a slotted large screwdriver and turn it out about two turns. Operate the trim up and down a few times (it won't move but will pump fluid).
Close the valve and see if the unit works now. If not the unit will have to come apart.
Remove the entire unit from the boat to work on it. Have a large metal pan to catch the fluid and hold a rag over any port you open. Please wear safety glasses. The units can hold a lot of pressure. Only work on one valve or port at a time and keep track of each check valve. Some of them under the motor are very small and easily lost. most parts are not individually available. Good luck.
Jeff