Crusader 454 still running hot

[oldsalty24]

Ive posted before, however I have still not fixed my issue, I really need a Crusader 454 FWC Expert to answer my questions - Starboard motor runs hot up to 200 degrees while running over 3000 rpms. Runs at 172 at idle with a 160 thermostat. As you may know these engines have freshwater cooled manifolds and saltwater cooled risers. The risers are new, the thermostat is new, the seawater pump is new, the heat exchanger was just rodded out and cleaned professionally. There is both fresh and salt water moving through the engine without any air bubbles or hestitation. I tested it yesterday for a bad head gasket, and it came out negative. It doesnt burn any coolant. The one thing that has me confused is that one of the manifolds is 25 degrees hotter than the other. My local marine mechanic, said it could only be 1 of 3 things, a bad circulation pump, [which I removed today and inspected, its fine and makes no noise and doesnt leak] or bad heat exchanger, or a blockage in the freshwater system. Even though I just had the heat exchanger cleaned, do you think it could be it again? any other suggestions? Thanks, Jon

 

[rodbolt]

Re: Crusader 454 still running hot

have you carefully checked your seawater pickup for growth? the seastrainer for debris and your clutch and oil coolers for blockage?
are you sure the correct seawater pump is installed? the 5.7 and the 454 take the same housing with a different pump cam.
install the 5.7 pump or pump cam on the 454/7.4 and it runs hot.
biggest thing I find is impeller pieces in the clutch cooler.
it aint fun to get to but you have to check it, be aware that occasionally the impeller pieces will stay in the seawater hose so flush the hoses as well.
your describing a seawater flow problem.

 

[liquidlew]

Re: Crusader 454 still running hot

I'm just gonna throw this out there, since your symptoms sound just like what I just had after a valve job and replacing thermie, manifolds/risers, impeller, water circ pump, and all new hoses. Check your timing! After pulling most of my hair out checking water flow to engine ( it was perfect) I took a gander at my timing, it was off around 6 deg. Clamp bolt came loose and timing moved so I put it back to where it's supposed to be and BINGO, runs cool as a cucmber, holding steady at 142 deg.

 

[oldsalty24]

Re: Crusader 454 still running hot

lew, i think you may be onto something there, Ive checked everything else, including seawater flow as mentioned above. What you are talking about would make it run hotter at higher RPMs only? Did your engine have the same characteristics?

 

[JCF350]

Re: Crusader 454 still running hot

. The one thing that has me confused is that one of the manifolds is 25 degrees hotter than the other. Thanks, Jon

There is your clue. I've sent bare blocks out to have them tank cleaned and once in a great while a piece or two of impeller would fall out of the block or sometimes other debris (don't ask me how the impeller pieces got there, they were large pieces too).