86 merc 350 started -Just purchased it 3 months ago from friend. New impellar in the alpha 1. I took it out and it ran good for the first couple of times. Last weekend I took it out and ran it pretty hard. On WOT the engine started missing, I checked gauges and was overheating (Pegged out).
Cut the engine off and sat for about 5 minutes. Restarted the boat and temp guage immediately went all the way down to under 120*. (normal temp from date of purchase) Ran the boat back to the marina with no overheating anymore.
The next day , put the boat in the water and ran it at WOT -this time for approx 3-5 minutes- Again -pegged out! I cut it off immediately and let sit for approx 5 min again- Boat would not restart like it did the day before.
After finally getting it started, this time it wouldnt cool down- Had to run it to keep off of rocks in very fast current. Babied it back to marina but noticed smoke coming from hose going from valve cover to air filter on the starboard side. Lake temp water was coming out of both Through Hull exhausts the entire time. Loaded it up and headed for the house.
Got it home and hooked it up to the garden hose- cant get it to overheat anymore. Cool water still coming out of the TH exhaust. Took the thermostat housing off and no thermostat. Took the water pump off and it was in good shape. Cleaned and put it back together with a 160* T-stat. Flushed the PS cooler and replaced all seals.
Started it and ran up to temp of 160* and let run for about 20-25 minutes and temp woulud not get over 160*. The water from the starboard exhaust was still cool and had good flow. The water from the port side was warm and not as good flow as starboard but same flow as always.
Planning on taking to the lake and running the S/_/ / t out of it this weekend.
My question is why the different temps in the exhaust flow? and why did I overheat to begin with?