TO TRIM OR TILT?
Q: I have a 1993 Thompson 210 Fisherman powered by a MerCruiser 4.3LX Gen II Alpha One. I have a question about trim and tilt controls. I normally bring the tilt down until the unit is level on the trim gauge and then adjust once underway. Would it make any difference, with regard to the gimbal bearings or any other components, if I initially brought the unit all the way down with the tilt and then came back to the level starting position with the trim? MARK BENNETT Chagrin Falls, Oh
A: It doesn't make a bit of difference. I'd tilt the drives all the way down until they're completely tucked in with negative trim. Then once you get the boat on plane and up to cruising speed, trim the drives out to give the bow lift and achieve maximum speed with the least fuel consumption.
Q: My 1993 Sea Ray 190 has a 175-hp Mercury outboard that keeps overheating. I've changed the impeller, water pump housing, and both thermostats, but it continues to run in the plus 200-degree range, ultimately sounding the high-temperature alarm. I've read through the shop manual but can't find any help. I haven't run aground or hit anything. Could there be a blockage? Is my only option to bring it in to be repaired by the local marina? BILL SHORTALL OKLAHOMA CITY, OK
A: Yes, you should take it to be repaired. I wouldn't settle for the local marina, however, unless it offers authorized Mercury service. Outboard manufacturers often make changes or discover service information that's model specific. They publish these as Service Bulletins. There may very well be one or more of these that pertain to your engine's cooling system. It doesn't sound to me as if you installed a complete water pump kit. You mention replacing the impeller and the impeller housing, but you don't say anything about the pressed-in, stainless-steel cup in the impeller housing and the stainless-steel impeller plate that's underneath the impeller. Both of these parts wear and require periodic replacement. If you operate an engine in silt- or sand-laden water, you can render these parts useless in a matter of minutes. They can become scored or develop wear overall. If this is the first impeller you've installed in this engine, you've been very fortunate. Normally, you should install a new water pump kit every other year. A complete kit includes: impeller housing and cup, impeller plate, impeller, gasket, and new hardware (fasteners, drive key, and so on). For the owners of new outboards, many dealerships are suggesting water pump overhauls after every 100 hours of operation. And be sure to get the stainless-steel parts inspected and replaced if they show any wear. It's cheap insurance compared to a fried engine.