Exhaust manifold swap

[jaybrassmonkey]

I wasn't running the motor on the hose, I had the outdrive off holding the hose up to the inlet. It had good flow from both sides, didn't seem to be obstructed.

 

[MRS]

I have a omc outdrive had same troubles and changed everything to do with the temp of the motor all looked good but still ran hot.
Did the impeller one more time fixed it all up running 160% right on the money if it is sucking air or if you ran with out water even for a few seconds can and will not be good. Change everything to new that as to do with the impeller had a merc outdrive on my last boat but do not remember what is involved with changing out the impeller.

 

[NHGuy]

You can briefly run it with the cooling hose off. Pull the cooling hose off the thermostat inlet and aim it in a bucket at 1000 rpm. See how much water it pumps in 30 or 15 seconds. There's a flow test value somewhere. I think you are supposed to get a gallon every 15 seconds or something like that. Hang on here and someone will know.

If it's not pumping enough it could have stuff like the pic, or a bad impeller, a kinked hose from drive to transom. or a piece of debris in there.