Mug 12v183 overheating saga cents more interesting

So I have two problems, both motors overheat, haven’t been out once this season. Port side slowly heats up but starboard is the stranger one.

Done so far:

Completely cleaned out reruns hulls/strainers. They were completely clean. Replaced fresh water circ impellers, they were in good shape. +Replaced thermostats, belts etc.

The strange thing is my my mug guy got back and checked it out. He thinks it’s raw water pumps. He took a hose off of the gear case and it spit out winterizing fluids and exhaust gasses. I removed the water hose that runs to the raw water pump from the strainer and it was full of winterizing fluid. It’s not pulling water through the system.

I don’t think mature makes the raw water pumps, prob Jabsco but I doubt a bronze impeller suddenly wears out. The only thing I can think of is a shaft breaking. The mechanic is taking the pumps apart but from what I’m reading on the web, the parts and labor to rebuild a pump is around $3k and a new one is around $5k.

Is there anything else that you think it could be? With the hose off of the strainer, water gushes in when I open the thru Hull. Could there be a clog somewhere else that’s not letting the raw water pump push water through the system like heat exchangers?

It was running fine when winterized and sat in the water for the winter. The starboard gauge read a little high before but the mechanical gauge on the engine would sat 175 or so. Nothing else was changed or done till the first ride down the river where the port got hot very slowly and the stud jumped right up and blew steam/water from the relief valve on the resivoir.

I’ve had to cancel two cocktail Cruses that I donated for charity and I have two more for VA families coming up%

Starting to hate boating

Geese, I need to spell check more often. Most importantly, my “mug” guy is supposed to read MTU guy. It’s AMTfrom both FL and up here in Ct in the summers. They are all very well seasoned with all mtu engines and I’ve never had a problem with them as well as four other MTU boats on our dock

Risers, didn’t think of that.
Here’s the latest
Port side all good, running at 175 on mechanical gauge on engine and laser temp gun. Gauge at helm is bad so I’m trying to find a sender and one of the square VDO gauges.
Starboard side still too hot at 225 degrees on mechanical and gauge and heat sensor gun.
We’ve done thermostats, raw and circulating pump, flushed a lot of crap out of the heat exchanger with some kind of salt/barnacle dissolver. The yard hooked up this concoction and circulated it for the day and loads of junk came out.
So, blockage somewhere else? Heat exchanger still blocked with something? Risers?
We went out with the kids and their friends for the first boat ride of the summer YESTERDAY just a short slow run to a local island and had a great day but I can’t believe we have only three weeks left before they go back to school. I can’t take everyone on our usual Block Island/Montauk trip with one engine running at 225 deg. I need help and nobody can seem to figure it out and aside of the thousands I’ve spent trying, I’ll pay more if someone can fix this. HELP!