One of my engines at mid to high rpm's is heating up to 170/180, what should i check ??

Ayuh,.... Change the Impeller,....

It's Always the 1st place to look, in Any overheat situation,...

If impeller is good, make sure you check the housing as well. You may want to take the thermo out and put it in hot water to make sure it is working right, or replace. If those three things are good move on to oil cooler being blocked by old pieces of impeller (end caps are easily removed). Next is scale from salt water use that may release and clog ports around thermo, recirculating pump, exhaust, causing poor flow. And last is the fitting between drive and transom can sometimes become clogged, collapse, or have a small leak that reduces flow.

What engine? 170 for a MPI engine sounds about right.

Also interested. New impeller, new recirc pump, and still 5-7 psi at anything above idle.

also cleaned the water pressure gauge sense line.

Check for an obstruction or some debris at the entrance to the oil cooler.

how old are the elbows and risers?they could be rusted up real good,causing a restriction.

All good info. guy's thanks and it's 5.7 mpi's that im running.

Pretty sure that motor runs a 160* t-stat.

It was packed full of impeller and a few small rocks.

I'd probed it before, from the top, and it felt like rubber so I ASSumed that was the hose on the bottom. Fast forward to today and I finally managed to remove bottom hose and immediately chunks fell out.

Moral of the story- don't be lazy.