I have been experiencing white smoke and for the first time in 3 years slight overheating. I have an 89 cat 30 with a Universal M25XP with around 850 hours (salt water). I have been running at 160 degrees and twice this year without any reason I have been hitting 175 degrees. The raw water strainer is not clogged. I overhauled the entire cooling system over the winter, including: boiling out the heat exchanger and pressure testing, new thermostat, new raw water pump and every cooling hose was replaced. My reward for all of this preventive maintenance is occasional borderline overheats. The white smoke is another issue, I believe the problem is in the mixing elbow. Has anyone changed the exhaust elbow riser to the nre Westerbeke part number 200266? Also, does anyone know the internal diameter of the inlet on the original waterlift muffler that came with a 89 Cat 30.The Westerbeke outlet is 2" and I plan on changing the muffler over the winter, if I can get the old parts to match up it may salvage my short sailing season. I had a sailing vacation planned, however without a dependable engine the wife does not want to take a chance. Actually I can't blame her. Around half of the people I spoke with think I could get away with the current condition, others do not think it is worth taking a chance.