Riser and manifold with fwc
 

Hello all,

I am new to boating and a little confused. I ran aground the other day ended up retrieving the impeller pieces and back flushed the system. I inspected all the oil coolers and hoses. The motor is a 454 with full fresh water cooling through the manifolds. I am now noticing the motor starting to creep up to 180. I turned around and headed back for further inspection.

No to the question

When I purchased the boat 6 months ago the gentlemen said the risers do not need to be changed since they are mercuiser stainless steel but now I am learning the riser will most likely need to be changed since that is the only section that sees saltwater.

Am I right? Also could this be the reason for the temp to rise.

Finally, I will be pulling the risers off for inspection, if I need new ones which one should I get?

Thanks

Most likely, you still have sand and mud stuck in the engine.

I have fresh water cooling that has a heat exchanger, how would the sand get in the motor?
Is this still possible?

Did you check/flush the heat exchanger as well? That and the risers are part of the raw water cooling and all needs to be checked if you are still having cooling issues after that event. You will see the condition of the risers once you take them off. If they are a wet joint riser with a block off gasket, you may need to drain the coolant out of the manifolds first so some doesn't pour into the engine when you break the riser to manifold seal.

Thanks Mr. Marine. I flushed the exchanger but not the risers. I will remove the risers tonight. I dont see anything else that is left in the system that I have not inspected except the risers. I did not think the impeller pieces made it past the oil cooler and exchange, but yeah maybe still have sand.

If new risers are needed any recommendation on replacement for additional power?

That would be Closed Cooling then and no stuff won't get into the actual engine.

I would still suspect an obstruction somewhere in the closed cooling system causing higher than normal temps.