I have a pair of 502s with TRS Drives in my 357 SR1 Formula. While out today, we managed to run aground while in the channel.

Anyway....I'm pretty sure I fried the sea water pumps. I got her back floating in deep water and opened the strainers to clear them out. They were full of debris (shells, grass, sand, etc). Got them both cleaned out and the motors were heating up after running a few minutes of idle speed. I shut them down and opened the strainers back up and there was nothing in them. I didn't want to take any unnecessary risk, so decided to call for a tow........much cheaper than motors.

I plan to do an oil change seeing as they got a bit hot. (figure it's cheap insurance)

OK so here are the questions.......

I know I will have to rebuild both of the raw water pumps, but don't know where they are located.
How to I flush the heat exchangers to be sure there is no remaining debris? I don't want to replace the parts and smoke them again because I didn't do a good enough job of flushing the system.
Are there parts available for these pumps that are better then others? Not looking for cheap way out...want to do this right.

Thanks in advance for all help.

Don't buy the so called run dry impellers. Buy the merc kits with the housing. Back flush the system by sticking a garden hose in the hose that dumps into the exhaust and let it flush out the system.
And the pumps are on the lower left when looking at the front of the engine.

So I need to disconnect the raw water outlet from the risers and connect the hose to a garden hose to flush it backwards correct? Should I have the baskets in the strainers or should the strainers be bypassed as well?

It might be wise to pull your oil coolers as well to make sure nothing got logged that back flushing will not get out. Impeller blades, shells, sand, pebbles and so forth can become lodged. Also you might get away with nothing stuck if your oil coolers if they are not honeycomb internally. Most stock OEM oil coolers are honeycomb internally so check that out as well.

You might be able to leave the oil coolers on and just pull both ends of the hoses off to run long rods / picks from front to back thru the honeycomb section to free up debris & clean out completely. We use a inspection mirror and camera also to view the inside if you can not get your eyes down to them.

Also we take pics and view them as well beforehand to see if they are clogged and or after clean up. Many parts that are in very tight areas, high quality digital camera pics can become your new eyes when working on boats especially with twins. So can inspection cameras. They are useful tools to have.

Thanks for the info BUP. I got her all cleaned up this morning and am about to go to order the pump parts. I'm thinking I might want to get a spare to keep on board.

Hardin Marine Makes stainless steel Lifetime sea pump housing rebuild kits. Just put one on my 502mag. Might check for your application.

Interestingly enough, the starboard pump impeller was toast, but the port side was in good condition. I replaced them both anyway since they were already apart. The starboard impeller pieces were caught at the oil cooler. Back flushed the missing pieces out of the cooler. Pumps seem to be working fine on a hose. Tomorrow is the sea trial.

Thanks to all for the help.

If there is any doubt about the condition of the pumps, look back at your exhaust. It should always be dumping water. If anything is clogged or worn out, it will be steaming under acceleration.

With sand, if you had more than 1/3 of the strainer full of sand, then there is always the chance you pumped sand into the blocks. Sand will accumulate at the bottom of the water passages. Remove your block drains and keep jabbing a coathanger into the drain hole to see if you're getting sand or debris out of the block. If yes, then keep flushing it until you don't get any - then do it again at the end of the weekend.

Closed loop system. No raw water in the block.