Flushing engines

[Dotty Sea]

Our dealer's staff told us we didn't need to flush out the engines on our 185 Sport which we bought new in June/July- we use it in salt water only and previously had a jet boat we had to flush out but they were emphatic that this process wasn't needed every time we used it.
Thoughts? Now I'm worried that we didn't - we ended up putting about 40 hours on the boat andit's in for winterizing now.

 

[never monday]

In therory they are correct. A raw water cooled engine will be thermostated at 140 deg F. This should be low enough to keep the salt in solution and allow it to just flow thru the engine. The problem is every engine has hot spots where it can get above 150 deg F. Another common problem with some of my diesels is at the point where the raw water is injected into the exhaust, there gets to be a build up of salt. This reduces power and can increase temps due to resistance in water flow.
As i said they are correct in therory. If your concerned, flush it can't hurt.

Pat

 

[STIHLBOLTS]

I use my boat in both fresh and salt water. I flush each and every time reguardless for two reasons.
1st in salt, to get the salt out and not to track it to a fresh water lake. (I also use salt away or salt terminator products when flushing)
2nd in fresh to clean out any sediment that I can. Mud can kill a engine as much as salt and other things can too.

Look at it this way, flushing the motor does not hurt it and if you get 5 full years out of your risers and manifold instead of 3 then your money ahead. And it is your money we are talking about. :thumbsup:

 

[fwebster]

Mud is not the sediment I worry about.

When you leave salt water in an engine, some of it evaporates out of the engine's cooling passages. The bare cast iron gets surface rust on it......and you'll get more of it quicker with salt water than with freshwater. When the engine is heated up the next time you use it, the normal expansion causes some of the surface rust to fall off in the cooling passages leaving fresh cast iron to rust. As this process continues, more and more of the sediment builds up in the engine block skirts where it cannot be flushed out. At some point.....6 years?, 9 years?, 12 years? the engine will no longer cool itself because the sediment has filled the lower part of the engine's cooling passages. At that point, they cannot be rebuilt either, so you will be repowering.

Richard gave you the bottom line on risers and manifolds earlier, but these are the weakest parts of the Mercruiser engine. The trade off between "keep it light" and "make it durable" is won by the "light" camp at Mercruiser. In my view, flushing cost you nothing but time. If flushing after use saves you one failed riser, one failed manifold or one failed gasket joint, you have probably saved your motor because a failed exhaust part does not happen when you are running the boat...it happens when the engine cools down. You discover it the next time out when the motor won't start because it is full of water and its too late to do anything but write a big check to the repair shop.

 

[rondds]

my boat's FWC, but i flush both emgines at the end of each weekend. everyone at my marina thinks i'm nuts, but all it costs is TIME. and i've said many times, it gets me INTO the bilge and forces me to nose around and check on stuff. you never know what you'll come across down there if you RARELY look.

 

[PMvdb395DA]

my boat's FWC, but i flush both emgines at the end of each weekend. everyone at my marina thinks i'm nuts, but all it costs is TIME. and i've said many times, it gets me INTO the bilge and forces me to nose around and check on stuff. you never know what you'll come across down there if you RARELY look.

The admiral??? :grin: :grin:

:smt018 Peter