The boat was splashed yesterday only to find out one engine had 2 PSI of water pressure at idle and @ 1500 RPM and it didn't take long for the temperature to jump to 130 deg. Once back in the shop I removed the thermostat which looked ok. But I replaced it. The circulator pump was removed but appears to look ok. Get back to that in a minute. The raw water pump was removed and rebuilt. The impellor had two small nicks in it.

So with the raw water pump being rebuilt and reinstalled and thermostat being replaced, Before I reinstall the old circulator pump. Which looks a little crusty around the medal wheel. What else would you look at? Would you replace the circulator pump?

Sounds perfect to me. Those impellers wont make much pressure at idle. Butttt if you're worried, pull the hoses off your oil cooler and thoroughly inspect it. Run a rod through each passage, you'll be surprised how many small items will come out and they all restrict flow/pressure.

I still need that white plastic sleeve that cracked when I pulled it to get to the thermostat. All the local parts places were closed. But disconnected the hoses that were accessible and I did get a 3/4" square chunk of scale from the oil cooler. All the tubes in the oil cooler were really clean.

So after rebuilding the pump and replacing other parts and fixing the issue of water flow. It appears that there is a significant temperature difference at the starboard exhaust manifold. So I am assuming there is blockage.

So if I had to replace my manifolds and risers what would you all recommend. Stock which are heavy but cheaper or something after market which is more but weighs much less? If I went with some after market it would have to be a "plug and play" I am running twin 454 MPIs

I'm very impressed with my new stainless marine manifolds. Solid construction, great sound.