The odd bank of my engine is warmer than the even. No complaints performace wise, no odd noises, but the odd bank is always discharging warmer water and a slight oil film on my swim deck. Any Ideas???
1995 454 MAG efi

I had an impellar rip to pieces on me, i thought i had it all out until i started it. Very little water would flow out the port exhaust. There was a piece stuck in there when that came out when i back flushed it.
So maybe there is something lodged in your cooling system.

I have a simular problem, my even side is heating more than odd. I too distroyed an impellar and i could not find all the blades. Anyone have any input? I could not find it in the oil cooler and I dont think it could get past it.

Just a thought would be to drain each petcock valve on both sides and see if you get the same amount of water out of each side. Do you use sea strainers? Sand, etc. can build up.
Just a thought.

what is the best way to back wash the cooling system?

Both of my 502mpi's have a slight difference in temp from the odd to even sides. On both engines the odd bank side header is probably 10-20* warmer and has slightly less water flow at idle out the odd side. There is not that much difference and I'm not really concerned about it since both cool just fine.

Like Griff said...its normal, the thermostat housing is splitdown the middle so half get the water bypassed and the other get the warm enigne water. Mine is all brand new everything and i noticed it the first dat i ran it. Its all Normal.