ever go to a repair shop and see twenty cans siting around? muff go over the strainers at the bottom of the motor and fill the cavity with water, works great and almost every body uses them. ever see a water impeller? its rubber in a very tight compartment, do not ever ever ever start your motor without water to cool the rubber , it only takes about ten seconds to ruin a water pump.

 

Yes they work unless muffs not installed properly, low water pressure or, in my case one time, slip down when I was not looking. Muffs are used by many. A clean trash can of water is more foolproof, but a hassle

 

I've been using muffs for 20 years on my 94 Merc and have never had a problem. I've only change the impeller 1 time about 6 years ago and it looked like it was still in good shape and it was still peeing strong.
Don't tell anyone but every time I get to the lake I crank the motor over in the parking lot until it fires before launching. I've heard it will ruin your impeller in 10 seconds but you can't prove it by me. I fish 60-70 times per year for what it's worth.
60 times per year X 20 years = 1200 times (not hearsay...just fact)
just sayin

 

I've been using muffs for 20 years on my 94 Merc and have never had a problem. I've only change the impeller 1 time about 6 years ago and it looked like it was still in good shape and it was still peeing strong.
Don't tell anyone but every time I get to the lake I crank the motor over in the parking lot until it fires before launching. I've heard it will ruin your impeller in 10 seconds but you can't prove it by me. I fish 60-70 times per year for what it's worth.
60 times per year X 20 years = 1200 times (not hearsay...just fact)
just sayin

Your mileage may vary.

 

I have used a testit flushit since 1974 with no problems whatever. It's the same as muffs except it has bolts through each end of metal plates which go around the lower unit and over the water intakes on each side. The bolts are held on with wing nuts. IT has never slipped or given me any trouble in all those years.

 

Your mileage may vary.

LOL....now that's funny

 

And to think that when she told me this I sold my never used, brand new muffs at a garage sale. Just my luck. I'll go buy a new set.

 

Don't run it fast on the muffs, not good!

 

Don't run it fast on the muffs, not good!

About all I plan to do is make sure it will start before I launch the boat.

 

Make sure you buy the muffs that feed water to both sides of motor. Cheap sets only have water line to one muff. A little more , but buy the ones that have water to both sides! My 2 cents

 

Not a thing wrong with running up on muffs, the only thing is you won't know if your water pump is ok or not until you put it in water. The muffs use your house water pressure to cool the engine.

 

Not a thing wrong with running up on muffs, the only thing is you won't know if your water pump is ok or not until you put it in water. The muffs use your house water pressure to cool the engine.

I wouldn't run up the motor past 1500 rpm on muffs. Your motor might need to draw more water than the hose can supply at higher rpms (depends on the quality of your hose and water pressure from the spigot). I once had my boat in the shop, and the mechanic ran my motor up to 2000 rpm, which collapsed the water hose. I could see my water pressure gauge drop to zero whereupon I immediately shut the motor off. The impeller was completely melted inside the impeller housing. There is nothing wrong with running a motor on a hose. You just need to keep the rpms down, make sure your hose is in good condition and not kinked, and that the muffs stay in position.

If you have a Merc, you will see a pisser stream when the motor warms up to the point where the thermostats open... the pisser outlet is downstream of the thermostats. It may take several minutes, and it may be a weaker stream than when your motor is running in the lake. If you had a water pressure gauge for your motor you would be able to instantly see when your impeller starts drawing water.

 

muffs works good for me. I have used them for working on my motors many times.

and like said before I would never dry start my motor. some people may get away with doing this. but its just not that much trouble to hook up a set of muffs.

I have heard of people using the same water pump for many yrs. but I fish lake erie a lot and don't want to get stranded out there with a bad pump. so every 3 yrs I change the upper housing, impeller, gaskets, and bottom wear plate. and if I think the key way is worn I will replace it. I have been boating for about 38 yrs now and have had a couple of pump impellers go bad after a few yrs back when I didn't know much about boats. but after I started changing them every 3 yrs I have never had one go bad.

I had one go bad and pieces of the impeller was missing. I changed the impeller and it was still overheating. so i checked all the lines going to the motor and checked the thermostat. but i didn't find anything wrong. so i called a charter caption that's also a marine mechanic. he asked me if i had changed the upper housing, i hadn't. so i started over and replaced the upper housing and a new impeller and the wear plate. this fixed my boat so i always just change these parts when i install a new pump.
sherman