Questions about cooling - etc

Morning all! I'm getting things done little by little and have a few questions. <79 Southwind PCM 351 last registered in 08>

I changed the impeller and seals on the Sherwood RWP and the intake had chunks of the old impeller built up in it. The impeller in the pump was intact so this debris must have been from a previous unit -- but how it got into that side I don't know.




I went ahead and pulled the brass plugs from the U fitting on the water hose on the front - as well as the block and trans heat exchanger. I was disappointed to see some putrid old water come out from each. It wasn't a ton but I'm a bit more afraid I may have crack issues now.

Considering the debris and mud I've seen already is there a good way for me to flush the system and / or check for blockages for flow or should I just run it on a timmy tee and let that clear the system? I plan on backflushing the water hose that connects to the RWP through the trans cooler and out through the hull unless you guys think that's a bad call.

Can I bypass the rwp and use the timmy setup to push water through the system? PO already installed a ball valve at the hull water intake -- but I have seen several threads where this is cautioned against so maybe a bad call.

Would a 79 have come with a strainer? Mine does not have one and seems like it's seen a fair flow of mud over the years.

And to wrap up here's some other humorous results from the PO's maintenance.

Checked behind the flappers and had this on both exhaust outlets.


Once clean the port port (lol) still looked like a problem.


So inside the starboard looked fine.


But the port had been shored up with a little 'Alabama Chrome.' The tape was waterlogged and very nasty with soot and rotten adhesive all over. I should have taken pics of the hose clamps -- they were so corroded I had to cut them off.


Bonus for the 12v hot splice having copper hanging out. I'm a stickler for clean wiring so it'll be soldered and hit with nice adhesive filled heat shrink on both splices.

What does the boat look lIke?

MrMcD wrote: Your making progress. The chunks you found from an old impeller are most likely also stuck up by the Thermostat housing, check and clean those ports also. Looks like bubba was at work on your exhaust ports. It will run better with 2 open exhaust pipes for sure.

Yeah you're right. I was hoping to do the minimum until I ran it but I shouldn't cut corners...

I guess a new thermostat is in order while I'm in there. Looks like 143 degree is the way to go for RWP systems. I'll be hitting the local boat supplier tomorrow for exhaust hose. I was thinking 'man that's not too bad' until I realized it's sold by the INCH and not foot!

Instead of back flushing like you mentioned, just take all your hoses off and make sure they're clear and at the same time you can inspect all the places the hoses hook to like the transmission cooler, the thermostat housing as already mentioned and the inlets to both exhaust manifolds.

The manifold inlets are a favorite spot for pieces to end up and go unnoticed till you overheat because all the water that goes into the engine has to go out the manifolds (like the diagram you found shows)and a restriction at either manifold can ruin your day.