does any one have any idea why my boat mite be running hot on top end ,i put a frech water cooling (closed cooling) system on it last year then this started ,put new timp. gage and sending unit, i did the die test to see if the head gasket was bad every thing checks out ,nothing put new S/M maifolds on, nothing, new row water pump still hot it ran at like 180 now it runs at 200-210-220 ich, what is a good running timp? its a 454 mpi all stock ex/ for the manifolds and risers ////////////////////////////////////i tested it this weekend and after puting a high speed pick up on its running great, temp is staying at 160 that works for me. thank you every one for your in put!! this is a great web site

170 temp check your therostat143 and to much timming will do it

ill check thanks

Check to make sure that the temp is being read on the same side of the cooling system it was before. If it was reading on the exit then it will be cooler than if it is reading it before. Hope that makes sense.

ill check i just puit a high speed pick up on to help flow more water in the heat exchange hoping it will cool beter im going to test it this weekend cross your fingers

check the water neck on the inside of the transom/gimble plate for build up....it happen to me. Ran fine at low RPM's but when I would get into it it would start running hotter. I pulled to the 2 7/16 bolts and removed the neck and it had a lot of build up restricting the water flow to the pump.

You could also have a kink in the feeder hose under the helmet. I had one once that was fine until I trimmed the drive up, then it would get hot. Found a kink in that feeder hose.

i tested it this weekend and after puting a high speed pick up on its running great, temp is staying at 160 that works for me. thank you every one for your in put!! this is a great web site

Just a small thing to check but I had a adventure replacing all kinds of stuff on a 500efi, replaced 3 thremastats, 2 impellers, the damm pump, hoses, all kinds of stuff. UGHH problem, gauge had gone bad, so before you tear through everything, see if you can borrow another temp gauge and check that.

Learned my lesson