Repair of 1996 OMC 48 SPL Engine
Posted: Tue Apr 05, 2022 7:27 pm
In another thread I described how I rebuilt the lower unit from a 1996 OMC 48 SPL engine. I am now trying to get that same 48 SPL engine working as a spare engine.
The power trim and tilt was not working. When removing the trim and tilt assembly from the engine swivel bracket I saw that someone had tried unsuccessfully to drill out the upper pivot pin. They also managed to break off a part of the bracket opposite the pivot pin. I soon realized that the pin was corroded solidly to the swivel bracket and was not budging. That explained the damage from someone trying to get it out.
The lower tilt shaft came off easily. The upper pin had to be cut off with a cut-off disc on an angle grinder.
With the trim and tilt assembly free, I investigated why the power trim and tilt assembly did not work.
First step in any analysis of a hydraulically operated device: check the hydraulic fluid level. I opened the filler hole and foamy fluid spat out. That indicated air was mixed with the hydraulic fluid. The fluid reservoir was drained. New Dexron hydraulic fluid was added to the reservoir.
The hydraulic pump motor was tested by connecting it to a battery. A loud screeching noise was made, but the ram did move a bit. Repeatedly applying battery power to the pump motor in short bursts eventually resulted in the ram moving up and down--in fits.
After letting the unit rest and the letting the air expel from the oil, more hydraulic fluid was added to the reservoir to reach the fill line. With each addition of more hydraulic fluid, the unit worked better.
Eventually I was able to operate the ram through five full-up to full-down cycles, as the factory service manual recommended.
Next, with the ram in the up position, the level of the hydraulic fluid is checked. More fluid was needed to bring the reservoir to the full mark. Then the trim and tilt assembly began to work very well.
The pump motor looks new; I think someone replaced it, but did not follow the instructions to correctly fill the reservoir with hydraulic fluid.
The power trim and tilt was not working. When removing the trim and tilt assembly from the engine swivel bracket I saw that someone had tried unsuccessfully to drill out the upper pivot pin. They also managed to break off a part of the bracket opposite the pivot pin. I soon realized that the pin was corroded solidly to the swivel bracket and was not budging. That explained the damage from someone trying to get it out.
The lower tilt shaft came off easily. The upper pin had to be cut off with a cut-off disc on an angle grinder.
With the trim and tilt assembly free, I investigated why the power trim and tilt assembly did not work.
First step in any analysis of a hydraulically operated device: check the hydraulic fluid level. I opened the filler hole and foamy fluid spat out. That indicated air was mixed with the hydraulic fluid. The fluid reservoir was drained. New Dexron hydraulic fluid was added to the reservoir.
The hydraulic pump motor was tested by connecting it to a battery. A loud screeching noise was made, but the ram did move a bit. Repeatedly applying battery power to the pump motor in short bursts eventually resulted in the ram moving up and down--in fits.
After letting the unit rest and the letting the air expel from the oil, more hydraulic fluid was added to the reservoir to reach the fill line. With each addition of more hydraulic fluid, the unit worked better.
Eventually I was able to operate the ram through five full-up to full-down cycles, as the factory service manual recommended.
Next, with the ram in the up position, the level of the hydraulic fluid is checked. More fluid was needed to bring the reservoir to the full mark. Then the trim and tilt assembly began to work very well.
The pump motor looks new; I think someone replaced it, but did not follow the instructions to correctly fill the reservoir with hydraulic fluid.