This weekend I got out on the boat for the first time in 3 months. My boat always runs at 160 degrees usually and doesnt put out much smoke in the exhaust. Boat fired right up but about 20-30 minutes in noticed the temp was up to about 170/175, but water was coming out and the exhaust seemed to have more smoke than normal and smelled a little differently. I watched for a bit to make sure temp didnt go up and that water was still cycling through, and eventually temp went back to 160 and exhaust seemed more normal. My question is could old or bad gas cause this smoke and temp increase?