running motor out of water

I have two questions re running my Mercury 4-stroke 90 out of water:

1. when using "ear muffs" over the water intake opening, is water supposed to spit out of the nozzle at the back of the engine lower unit. like it does when the engine is operating in the water? If so, will the water immediately start to spit, or is there a noticeable time lapse of a few seconds to allow the water to reach the nozzle?

2. the lower unit has a threaded flushing connection where I can attach a garden hose to flush the cooling system. Can I use that instead of the "ear muffs" when running the engine out of water (the Mercury manual specifies that the engine must be running when flushing in order to open the thermostat)?

Re: running motor out of water

wow what yr motor,you should be able to use that conn,beware i used a cheap pair of muffs and smoked my impeller,now i just fill a large bucket i bought at lowes so the whole bottom is in water,some garden hoses just do not have enough pressure,it doesnt take long to burn impeller out,make sure your getting plenty of water through lower unit.

Re: running motor out of water

The hose connector is supposed to work to flush.I(old school) just don't trust them.
It should take a few seconds to spit water.The hose attached to the house might not have enough pressure.Turn it on and see if it trickels or really pumps.
Then duct tape them in position.Use lots of tape.
Yup needs to run to flush right.J

Re: running motor out of water

i really agree with the bucket situation. I feel like some water hoses lack the neccesary pressure that you will need to keep the engine "full" of water, and if it runs out of water, it may hurt the impellars performance.

Re: running motor out of water

Actually,the opposite is true,as far as garden hose pressure.Most people turn the hose on too high.The waterpump is designed to "draw in"water at idle.A bunch of pressure is not needed.It is best to run in a barrel to allow some backpressure.

Re: running motor out of water

The "muffs" hold a cup over one side,and supply water to the other side. At about 1 lb pressure, it will allow it to spill around the cups. If there's enough water to spill a little when the engine is running, it is as much as it will get when immersed in a lake.

All the water at the tell tale has to go through the thermostat(s). If the supply water is real cold, it is possible that it only dribbles, and that would be normal.

At all times when the engine is running, there should be a good flow of water out the prop hub. You can't see that in a bucket, so for checking purposes I prefer the muffs.

hope it helps
john

Re: running motor out of water

It would have to be one big bucket to fit and supply enough water to a 90hp. The muffs work just fine if you put the on and watch them. If you are worried about them falling off then get the set with a rod that goes through the lower and the other cup screws onto the back then there is no chance of slippage. It takes my talltale about 5 seconds to start up, the same as when I am at the lake.

Re: running motor out of water

Thank you all. I appreciate the information.

The lower unit is too big to fit into the largest buckets I have, including a large garbage bin. The muffs I have have a wire that passes through the intake so they won't slip away.

Not being mechanically inclined, I am a bit hesitant about winterizing my motor myself. Up to now it has been winterized by the dealer. But after having spent $1 700 this summer to replace the head, I need to try to find ways to cut expenses.

This motor which I bought brand new in 2002 has less than 200 hours on it (mostly when the grand kids visit), and this spring the dealer reported that there was very low compression in two of the cylinders. A refabricated head needed to be installed.

I suspect that what may have caused the problem is that I left gas (treated with ethanol) in the tank for a long period (9 months). The water separated, gathered at the bottom of the tank and caused the engine to overheat. At least that's what I gather from what I have read on the internet about the consequences of leaving ethanol treated gas in the tank during winter storage...

Re: running motor out of water

Here is information I received from Mercury in response to two questions I asked concerning winterizing my motor:


"...When flushing the cooling system, you can run the engine if the ear muffs are on and the water hose is connected to the engine and running.

As fogging is usually performed on two-stroke engines, we do not recommend fogging your four-stroke engine. You may spray storage seal on the cylinders, through the spark plug holes once the spark plugs have been removed, to winterize the engine as this seal is thinner. ..."

Re: running motor out of water

So, you would need two garden hoses running to your motor, one for the muffs and one for the flush fitting?

Re: running motor out of water

Yes. I ran one hose to the boat then attached a "Y" connector from which I ran two short hoses.

By the way, at first I was concerned that there was no water spitting from the back of the motor...until I noticed that the flushing connection uses the tell-tale opening!

Re: running motor out of water

Hi,I have a 2007 200 hp Optimax.I got it new and used the screw in hose fitting and burned up the impeller so I took a hammer too it and replaced the impeller,so I would NEVER use that fitting.

Re: running motor out of water

The hose fitting on the outboard is for flushing without running.Using muffs you can start and idle.

Re: running motor out of water

Ive always used muffs without any ill effects to a motor. If water is spilling out around the muffs when running, there is plenty water supply.
Running a motor in a barrel aerates the water which is bad.
That my .02