Muffs or Tank for for running engine

[seamegr]

I can't remember where, but someone mentioned using a tank of water for running a stern drive in. I don't think anyone said yes or no. Would there be a problem? You'd have to make sure that the water in the tank was cooled and replaced.<br /><br />My concern is that my water tap pressure is around a 100psi most times and I'm afraid of overpressuring the engine. Or does the pressure drop to an acceptable level thru the muffs.<br /><br />Greg

 

[Fishermark]

Re: Muffs or Tank for for running engine

Any excess pressure is forced out the side of the muffs. The problem of excess pressure relates to those outdrives that have a built in "hose bib" that you screw a hose onto. I don't see any value, (but a lot more work!), to using a tank.

 

[Scaaty]

Re: Muffs or Tank for for running engine

just don't turn the tap on all the way...and start the motor as soon as possible AND shut it down AND the water off so you don't pump water into the exhaust risers and have no exhaust pressure to force it out. Do NOT let water get in the cylinders. Best bet is do what ya need to do, and when done, disconnect the water and run the motor again for about 5 seconds

 

[TwoBallScrewBall]

Re: Muffs or Tank for for running engine

disconnect the water and run the motor again for about 5 seconds

My OMC manual shows the amount of damage that can be done when running the impeller dry for even a few seconds, it happens very very quick. It is not recommended to run for any period of time without water to the engine. With risers and manifolds in good condition there should be no way you could pump water into the exhaust of the engine through the muffs, whatever water made it into the manifold's water passages would either just sit there in the water jackets or drain out down the outdrive.

 

[seamegr]

Re: Muffs or Tank for for running engine

Thanks for the replies. Yes there is lots of water coming out from the muffs even with the engine running. Yes, very careful to always have the water running before firing the engine.<br /><br />Greg

 

[Fishermark]

Re: Muffs or Tank for for running engine

One more point to consider -- it is better to have too much than not enough water pressure. I had always heard that you needed to be careful with having too much pressure, and the article I read suggested only turning the hose on "about half way." Yeah, that's a real big help. I would guess one person's "half way" would be far more than another's "full blast" and visa versa.<br /><br />I fried the impeller in an Evinrude outboard I used to have because I didn't turn the water on enough for it to reach the water pump. Oh well, live and learn.

 

[salty87]

Re: Muffs or Tank for for running engine

i watch the water hose. if it's soft or collapsing then give it more water. if the hose is bulging or too hard, i turn the water down a little.

 

[Scaaty]

Re: Muffs or Tank for for running engine

damage that can be done when running the impeller dry for even a few seconds, <br /><br />Thing is it isn't dry...you just had water going to it. That will lube it for quite a while. You do more damage everytime you start it after sitting and water evaporated! And Volvo Sterndrive Manual in my hand sez easy on the water pressure. My pumps in my 4 boats are just fine...common sense is the watchword here. And forcing water in to a inboard without it running can get water into places it don't belong. Why do you think risers go up? Anytime exhaust and water go out together, it can be reversed and cause trouble. Again...common sense.

 

[Boatist]

Re: Muffs or Tank for for running engine

I think you can do either. With muff's if you turn it on too high the spring push away and the rubber flexes and you spill a lot of water but the pressure to the water pump very close to the same. <br /><br />Only time I think running in a tank is needed is when you want to see how much water your water pump pumps. With muff's you can force some water thru a worn out inpeller and think the impeller is pumping strong when it is really the hose pressure you are seeing.<br /><br />The riser goes up to prevent a stern wave from forcing water up the exhaust into the engine cylinders. On the trailer with muffs you are not going to get a stern wave. If you shut the engine off and leave the muff's water on witer will just run down and out the outdrive. To force water back into the cylinder you would have to plug exhaust with a rag or something.

 

[Scaaty]

Re: Muffs or Tank for for running engine

Boatist...agreed...some blanket answers don't cover everything. My big boat (in salt)has a fresh water flusher I devised onto the thermostat housing, and this has the leg in the water, which can be a sort of "rag". Long story..just being paranoid on my part, as I am a preventive maintenance freak! Great answers by all. Night all..

 

[f_inscreenname]

Re: Muffs or Tank for for running engine

I would use muffs. What the motor doesn't want will just blow out the sides of the muffs. I would never use a tank. Unless you build a swimming pool size tank you will you will running the same water through the motor over and over and that aint good.