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Author Topic:   NEW 90 HP 4 stroke Problem
Knot at Work posted 09-08-2003 11:19 AM ET (US)   Profile for Knot at Work   Send Email to Knot at Work  
Hey guys a heads up.... after a great day of boating I was flushing my engine using the hose port on the motor. The rubber and hard plastic screw port had backed off the mounting plate ( it is cheaply designed and all plastic, a BIG Dissapointment with this motor) no water was flowing to the waterpump so I had the potential to cause damage to my motor.

I tried to pump water in through the lower water intakes as well and no water came out the eject port... so I took the cowling off to look for the matter why, I notice the cork screwed rubber hose to the water pump was kinked and had to reconnect the hose connector.

I am sticking to the bottom flush for now on and ALWAYS take your cowling off to inspect that prior to flushing!

hope this helps you keep running!


JBCornwell posted 09-08-2003 11:33 AM ET (US)     Profile for JBCornwell  Send Email to JBCornwell     
Hi, KAW.

If your flush port is the same as on my Suzuki it is not intended for use with the engine running.

The water does not go through the water pump, and if you run the engine you will cook the impeller.

If you want to flush with the engine running, always do it with the "muffs".

Red sky at night. . .

Barney posted 09-08-2003 11:48 AM ET (US)     Profile for Barney  Send Email to Barney     
KAW, I did the same thing. The plastic fitting is easily pushed in. Put everything back together and get a brass quick connect hose fitting. Screw one end of the quick connect to the engine and the other to the hose then connect. That will take the stress off of the plastic fitting on the outboard when connecting the hose. It was frustrating until I did this myself. For those that own other brand engines, seems like all other brands, the manual says "run" the engine even in this backflush configuration. I don't like it either. Jim
Jimm posted 09-08-2003 11:53 AM ET (US)     Profile for Jimm    
Just for info; on the Merc 90 2 stroke the manual states you may run the engine while flushing if you care to.
Knot at Work posted 09-08-2003 12:18 PM ET (US)     Profile for Knot at Work  Send Email to Knot at Work     
Yes the manual states run it with WATER flush for at least 5 minutes.

Barney, Great idea on the quick connect,,, I think I am going to stick with the muffler though..

JB, for the 4 stroke Mercury the port is designed to "back" flush the system. It is threaded for a hose to connect. It was supposed to replace the muffler way of flushing, I am not sure of the benefit of going that right vice the muffler

DCM posted 09-08-2003 01:13 PM ET (US)     Profile for DCM  Send Email to DCM     
I have a dumb question - you are flushing the engine because you're running in salt water, right?
Dan ( fresh water boater, can't ya tell? )
Knot at Work posted 09-08-2003 01:29 PM ET (US)     Profile for Knot at Work  Send Email to Knot at Work     
No such thing as a dumb quesion and Boston Whalers!

Flushing motor because I rin in shallow water in the river and get a lot of silt and sand in the intakes.. additionally water is brackish.

You should flush the motor regardless in my opinion

Maximus posted 09-08-2003 06:11 PM ET (US)     Profile for Maximus  Send Email to Maximus     
I did the same thing...once. The motor really didn't sound happy running with the hose connected to the back flush port and after 20 or seconds I stopped the motor and resumed the normal ear muff flush.

The back flush does scare me. You are forcing water against the flow for the impeller. Doesn't make much sense.

I flush the motor after every saltwater use.

Barney posted 09-08-2003 09:09 PM ET (US)     Profile for Barney  Send Email to Barney     
Our boat is on a lift, so I use the back flush fitting. Max, you are right the 90 doesn't sound good when back flushing through the fitting. I would like to talk to someone at Mercury about this setup. The Honda 90's have a brass fitting so it is a solid connection and when you turn on the water you see water coming out of everything including the visable discharge. It doesn't require running either. Jim
boxers posted 09-09-2003 09:24 PM ET (US)     Profile for boxers  Send Email to boxers     
Our Yamaha 115HP was bought new and kept year round in salt H20 from 1991 to 2002 never flushed. Just cleaned the boat and tilted the motor out of the water. Aside from replacing a trim/tilt switch at 7 years "Zero Problems". Makes you wonder... when other makes require impellers ect ect. Why is the Yamaha so reliable?
lakeman posted 09-10-2003 06:20 AM ET (US)     Profile for lakeman  Send Email to lakeman     
Flush, flush, flush, Unless you have money to burn. This is very true if you have a newer engine that runs at the 143 temp. Most of the newer dfi,s and 4 strokes run hotter theromostats.
I even flush with salt away, is suppose to clean the water jacket after several uses. I do this even if I run in fresh water. Many of the lakes have as many harmful properties as saltwater, that will even etch stainless steel chains that hold the marker bouys.

My preventive maintenance, some things only take a few minutes, others take hours.

jimh posted 09-11-2003 09:16 PM ET (US)     Profile for jimh  Send Email to jimh     
[Removed off-topic comments--jimh]

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