flushing a 1900sc with 4.3 v6 mercury engine

[speedy]

Hi,

Ive just traded in my yamaha jet ski in for a maxum 1900sc and I'm very new to the motor boat world. When flushing the engine does it matter if the engine is running 1st or water flowing 1st?
Also theres a pump switch on the dash is that used for flushing or something different?

Any feedback would be a great help

Speedy

[tglee]

Water should always be running first. You want to make sure you have good water flow to the rubber impeller before you attempt to start the motor. The switch at the helm is for manually starting the bilge pump. What year is the boat?

[Brianm]

Congrats on the boat and welcome! Like was said above, make sure you have good water flow and that the "muffs" are secure before starting engine. Best to have someone watch to make sure water is flowing out of the "pee holes" while you stand at helm with engine running. When done, shut motor off then shut water off. If flushing after salt water use, IMO, you should run Salt Away through for the last bit. Hope this helps. Enjoy your toy!

[Thejanitor000]

Originally Posted by Brianm

Congrats on the boat and welcome! Like was said above, make sure you have good water flow and that the "muffs" are secure before starting engine. Best to have someone watch to make sure water is flowing out of the "pee holes" while you stand at helm with engine running. When done, shut motor off then shut water off. If flushing after salt water use, IMO, you should run Salt Away through for the last bit. Hope this helps. Enjoy your toy!

Is it necessary to start/run the engine when flushing after salt water use? I typically do but a gentleman walked up to me on yesterday while I was and told me it wasn't necessary to start the engine. He suggested that putting the muffs over the holes and simply running water is sufficient. Any opinions? I have a 2300sc.

[pascavone]

only difference is the engine running "might" open the thermostat if your run it long enough to let the fresh water into the engine block.

I say "might", because your cold hose water is in fact closing the thermostat and your burning fuel to heat the water, like 20 min.....

[Huddo007]

If you want to get really fancy you can try running a cleaning agent after you have done your flush (for RAW cooled engines), a common and proven agent here in Australia is Bobs he did tests on his products, and proved reduced salt build up and corrosion of block water pumps, extended life of impellors etc., I did the smart thing and emailed his business and asked for the MSDS (material safety data sheets) for his product as I was "storing" it a my workshop, his lovely assistant sent me a copy which included a full chemical breakdown, it was 86% diesel 10% cloudy ammonia and 4% common dishwashing liquid, the diesel left a small oil film on all components, the ammonia broke down the residual salt and the dishwashing liquid made it all water soluble, the procedure was to flush engine as per usual then at the end place 100ml per litre of engine capacity into the hose line then start engine again and turn off before the milky fluid stopped flowing from the "pee holes", I used this for 5 years and I know I had no water pump or impellor issues, and I’m expecting flack here but every year checked my impellor and never did use the new one I bought the first year

[ss3964spd]

What Pas said - running the engine will open the t-stat.

Flushing without running the engine will only flush the exhaust manifolds, and will probably be restricted by how much can get past the non-spinning impellor in the drive. Remember how water flows through the engine block. Water from the drive enters the water pump on the front of the engine, which then circulates through the engine - starting at the cylinders then up through the cylinder heads, and finally exiting the engine through the t-stat. If the T-stat is closed the water can't get out so it goes no where.

I've flushed mine zillions of times with muffs and a hose. I always start the engine, it always gets up to operating temp - just like if it were in the water.

[Thejanitor000]

Looks like I'll continue starting the engine. Thanks for the feedback!

[shrew]

If I recall Merc advises to specifically run the engine and make sure it's run until the engine comes completely up to temp.

[Thejanitor000]

Thanks Shrew. Looks like I'll definitely stick to running the engine.