Starboard riser hotter than port

[Pumpe]

Fired up my 99 ski nautique raw water cooled GT40 ProBoss and ran it on a hose connected to the strainer.
With engine temp about 130F the starboard riser was just cool enough for me to hold my hand on top, a little warmer and I would have had to remove my hand. The port side was more or less cool to the touch.

Rebuild waterpump, the old impeller was in pretty good shape but the bearings and seals were toast.
Also rebuild the exhaust pipes and muffler and removed the internal baffles that had come loose.

New exhaust hose installed

Are something wrong when one side gets hot that quickly?

[Pumpe]

Since it's a lot of work to remove the pipes ande muffler I just tried to flush the manifold with a garden hose on the front connection, Looked like it flowed well, not much force needed to hold the hose in place. I will clean the little cap over the thermostat where the water is coming from the raw water pump but could the problem be inside the riser?

Seems like a lot of people have one side running hotter than the other but not everyone have the same side hot

[wakejunky]

Did you check the top of the thermostat housing where the hoses connect from the engine to the risers for cooling. I had the same problem, turned out to be old impellor pieces that had plugged the hose to one of the risers and caused it to get really hot.

[sfjakey]

Riser gasket has failed

[Pumpe]

Riser gasket has failed

Yea not quite. The gasket was missing. Stupid PO installed the riser without the gasket.

[sfjakey]

Bad news. That means water probably made its way into the valvetrain

[sfjakey]

I would pull the manifolds and look for signs of water intrusion. If you run in salt or brackish waater, I would be very concerned.

[Pumpe]

Maybe but it could be that they just slapped it together with exhaust sealant and then sold it to me. I have only had it on water for a 10-15minute test run.
When I look back he was pretty eager to sell it since he trailerd it almost 200miles on a trailer without suspension or brakes (stupid swedish thing allowed on the roads at less than 18mp/h)