[Capt. Paul]

Hi All,
I have a 1999 2900 Coronet with 7.4 mpi Crusaders.
The port engine runs 5 to 10 degrees hotter than the starboard.
Around 185, and there is noticeable steam in the exhaust. I have just changed all exhaust elbows and flushed the raw water systems with barnacle buster and replaced the engine zincs.
The impellers are only a few months old.
Does anyone else experience steam at the exhaust?
Regards,
Paul

[Matta0413]

When you changed the impellers did you check the condition of the cover plate? Was it scored at all? I have an 02 with 8.1's and had the same problem. The cover plates had some good scoring on them which means most likely the rear of the housing may have some scoring as well. I change the water pump and the temp dropped right back and the steam went away. She wasn't getting enough raw water. You can also try back flushing the system to see if any crap comes out of your raw water system. You haven't mentioned the oil coolers have you checked on those? Also take the ends off the heat exchangers and make sure there is any blockage there as well? Were the old impellers missing any fins? If so they the missing fins are most likely in your raw water system somewhere. There are a number of things that can be causing her to run a little hot.

[Capt. Paul]

Thanks for your response. I have to go back and look at the cover.
I did flush through the oil/trans cooler and heat exchanger with barnacle buster for over an hour. There was just a nub left on the cooler zinc anode which was gone after the flush, so I know the flush was somewhat effective.
I will have a better look at the pump for impeller condition and scoring.
Thanks again for your input.
Paul

[Capt. Paul]

So I finally got to the bottom of the issue. After removing the U cooler and heat exchanger to have them cleaned/tested, the engine was still running hot and steaming. Swapped raw water pumps, same thing.
Looked at the hoses from the thru hull to the strainer and they were cracked at the bends so I decided to change them. While off, I opened the sea cock and stuck my finger down there. The port side had barnacles inside the ball of the valve, thus restricting the flow.
I have always heard to stick with the easy stuff first. Good maintenance on the rest of the system though.
Hope this helps someone else.
Paul

[Matta0413]

Glad you found it