Running on muffs questions and other I/O questions?

[Brewman61]

Re: Running on muffs questions and other I/O questions?

Odd that it says limit run time on muffs to 5minutes on my muff packaging.

Lawyer got his say so in the product's packaging.

 

[HT32BSX115]

Re: Running on muffs questions and other I/O questions?

I imagine it's probably the reason that the engineers that designed those set ups put hook ups where they can easily be accessed in the engine bay... and no, it's not just for flushing, read a manual and it will tell you.

The "engineers" that designed those "set-ups" were not Mercury or Volvo. Neither Merc or Volvo has a problem with using out-drive flush adapters.

The raw water pumps get water just as fast.


From a Mercruiser maintenance manual:

/////////////////////
5. If flushing the cooling system with the boat out of the water:
a. Lower sterndrive unit to full down/in position.

b. Remove propeller.

c. Install the appropriate flushing attachment over the water inlet holes in the gear
housing.
6. Connect hose between flushing attachment and water source.
7. With sterndrive unit in normal operating position, open the water source fully.
8. Place the remote control in the neutral idle speed position and start engine.

NOTICE
Operating the engine out of the water at high speeds creates suction, which can collapse
the water supply hose and overheat the engine. Do not operate the engine above 1400
RPM out of the water and without sufficient cooling water supply.

yada yada...

 

[bruceb58]

Re: Running on muffs questions and other I/O questions?

The manual for the Volvo 5.0GXiB in my boat specifically warns to NOT run the boat out of the water using the flush/drain hose that you've seen in the engine compartment. To run the engine out of the water requires muffs and water supplied to the outdrive water intake.

That's because out of the water it introduces air into the raw water pump.

 

[superbenk]

Re: Running on muffs questions and other I/O questions?

Running on muffs is only ok if you have a mercruiser alpha.
OMC's strigner's have to be submerged to get water to flow unless you have the special coupler to hook up a hose directly.
I'm not sure about all volvo's but the ones that I have seen have a hook up inside the engine bay for water hook up.
And again with bravo outdrives I have seen where water must be hooked up to a special fitting in the engine bay.

Not all outdrives have the impeller in the lower unit.
OMC cobra's are in the upper part of the outdrive IIRC.
Volvo's and Bravo's have an impeller that runs off the belt on the engine.

Wow...a ton of misinformation in this post!

The only thing that is really correct is flushing on a stringer drive and that really only applies to the older electric stringer drives. Everything else can use muffs.

Agree with bruceb58, lots of misinformation. I can speak to the OMC Stringer portion. Only the electric Stringers (pre-1978) cannot be run on muffs. I run mine on muffs all the time & water circulates just fine. Each impeller I've replaced for regular maintenance has had zero indication of being under-lubricated or run dry. The impeller sits at the base of the upper gear case just above the lower gear case. I think this is roughly the same position it's in on a Merc so that has zero bearing on anything.

I have no idea if you should run on a full open spigot or not, I always run with the spigot fully open & the muffs stay put & everything works fine. Keep an eye on your flow & the engine temp gauge & you'll be fine. I try not to run the RPMs up too high without load just because it "feels" wrong. I imagine the engine internals prefer to have some load on them to work/wear properly.