2014 350 mag cat, port manifold/riser considerably hotter?

[lrdchaos]

Just fired off my new to me boat to make sure everything made it through the winter. Ran the boat on the muffs for probably 30 minutes from idle up to 1400 rpms. One thing I noticed, and it might have been this way when I bought the boat is that the port side riser/cat was considerably hotter than the starboard side...especially early on. When I first started the motor and it was idling or throttles up close to 900 rpm, the starboard side was relatively cool where I could barely touch the port side. After awhile of idling at 1400 the starboard side had warmed up and I could leave my hand on it for 3-4 seconds and the port side I could leave my hand on for 2ish. At that point the port side had cooled down from what it was a few minutes before.

I’ve circled what I was touching, not my engine but it’s a reference point, and I realized that’s the starboard side as well.


I felt them when running the boat before I bought it and both we equally hot at that time.

Could the temp difference have something to do with water flow with the thermostat

edit....boat was sitting in the street with the starboard side a few inches lower than the port due to the crown and the road. Also, the water coming out of the back of the transom showed good flow on both sides, with the port side being a little warmer but not excessively hot. Also, the hoses coming out of the back of the risers we cool to the touch on both sides, leading me to believe I have good water flow.

 

[Scott06]

Its typical to see a 20-30 degree difference in manifold temps. If you can keep your hand on them I suspect you are fine. Might want to use an IR thermometer to check temps.