Running on muffs questions and other I/O questions?

[ihaveabrownboat]

Have been reading the forum for a few weeks and finally registered to ask a question. I know it's dumb. But I don't want to screw anything up right off the bat. Looked through and didn't find an answer too quickly so asking away.

Have a new to me I/O boat. Never had an I/O boat before. Just a couple of manual outboards.

To run on muffs should the engine and outdrive still be up like when it's normally on the trailer? Or does it need to be lowered?

Is it ok to run it on muffs long enough to get things to warmed up for an oil change?

Then I/O questions. It will probably be clear when it gets to using it. But would rather know first. I'm not sure I get the in/out and tilt/trim jargon. Can someone do an I/O for Dummies? To put it in the water and prepare to run?

Thanks.

 

[partskenn]

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

1- I have always lowered my drive all the way down before running it on muffs, don't know if you have to, but I always have.
2- Yes, you can run it for 5 minutes or so to warm it up, just make sure you always have a good water flow, and that the muffs stay where you put them originally.
3- After you launch the boat, assuming the water is deep enough, drop the drive all the way down to start, you can trim it back up a little later for maximum performance. You don't want to turn the prop with the drive still tilted up in the trailer position.

 

[UncleWillie]

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

IN = Drive Down = Bow Down = Bottom Button
OUT = Drive Up = Bow Up = Top Button

The drive ALL the way UP is called the trailering position and is only for transportation with the engine OFF.
The Drive down or up only as far as the first limit stop is the normal operating range.
Operating the motor in the trailering position is not going to instantly kill them. Just don't make a habit of it.
The U-joints are badly stressed if you operate the motor in the trailering position.
The U-joints and everything else in the drive except the propeller output shaft are spinning whenever the motor is running.
Being in Neutral does not help... or matter.
The Rubber Bellow seals are stressed if you STORE the drive in the UP/Trailering position.
The drive will hold water in the up position.

Drive up = Trailering/Moving.
Drive Down = Motor Running/Storage.

If you do not have a definite reason for it to be UP it should be DOWN.

 

[Mason78]

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

If you are running on muffs you defiantly want to lower the drive unit. Running with the out drive in the trailer position causes the U-joints inside the drive to bind up.

 

[fotto]

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

I was in same position as you (OP) last year with not only first boat but first I/O boat to boot. After reading many threads here with advice, I try to adhere to everything said in above posts. I have also read that when running on muffs that you really shouldn't turn your water source all the way up, maybe 1/3-1/2 open from spigot as the pressure could blow through a gasket (or something) in the lower unit. Don't know for sure though.

I am very careful to make sure the drive is down at least to upper trim limit or lower before starting the engine at all. I forgot to do this once when launching at dock and ran for 30-40 seconds with it up...was freaking out but didn't have any noticeable damage with U-joints.

 

[Brewman61]

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

I lower drive, put on muffs, open spigot to about half, run motor at idle, or no higher then 1500 rpm.
I've heard the same thing regarding not running the water at fully open, can't remember why anymore but the explanation made sense to me at the time. I think a lot of us have accidentally shifted into gear with the drive fully rasied, just as many of us have forgotten to raise the lower unit pulling out the boat once it's on the trailer.

 

[Maclin]

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

Brewman, I just want to make sure it is understood that starting/running the engine at all with the drive up stresses the u-joints, they are spinning all the time no matter if the drive is in neutral, or forward or reverse.

 

[bruceb58]

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

There is no reason not to have the water on full. The impeller is limiting the amount of water being delivered. Any excess water will just leak by the muffs.

The reason you see a limit on the RPMs is that some people's water supply can't keep up with the flow requirements when the engine is at higher engine RPMs. If you have enough flow, there isn't any reason not to be able to go higher. I run my engine on a high pressure high flow water line. If I run my engine at 2500 I still have water leaking by the muffs.

 

[UncleWillie]

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

I think the only reason NOT to have it on full flow it that No/little water goes through the cooling system when the engine is Off, All the water squirts out the side of the muffs.
It would be possible for the muffs to just blow/float themselves off the lower unit between the time you turned on the water and climbed into the boat to start the engine.
After starting, you can always open the water flow to ensure you are getting more than you need.
It would always be a good call to have a safety person outside of the boat to watch the Muffs and keep the kids away.

 

[Part-time]

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.

 

[bruceb58]

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.

 

[ihaveabrownboat]

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.

Thanks for all the advice so far. Hopefully will get to it tomorrow to exercise the advice. Not sure my switches are doing exactly as described. I think the trim side of the one switch may be dead. The up and down both work. Though I seem to get more "up" if the "up" part of both switches is held down at the same time. If that makes sense.

At least I'm getting the drive up and down. That's more than I knew how to do this morning. Now have to go start a new thread about the fuel fill and hope I can figure out how to post a picture.

 

[ktbarrentine]

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

Ihaveabrownboat: What type of engine/outdrive combination are you running?

Recommend you visit the mecruiser forum (here):

http://forums.iboats.com/forumdisplay.php?f=21

and review the posts in the first two stickys. A wealth of information you really need!

 

[Part-time]

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

Wow...a ton of misinformation in this post! Everything else can use muffs.

I hope you don't work on anyone else boats except for your own...
If you start any stringer or a mercruiser or a volvo with the impeller on the motor you can burn out the impeller long before the water can get there.
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.
Cobra outdrives are far and few up here so I have only worked on two of them and both had water hook ups in the engine bay to run the engines out of water.

 

[Part-time]

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

Not sure my switches are doing exactly as described. I think the trim side of the one switch may be dead. The up and down both work. Though I seem to get more "up" if the "up" part of both switches is held down at the same time. If that makes sense.

OK, it sounds like you have an older mercruiser outdrive.
They are fine to start with muffs.
The 3 trim buttons are trim down (the bottom one)
trim up (the middle one), now this one will only go from the full down position to apx 30 deg. It is the upper limit of the drive with the motor running.
And when you press both "up" at the same time that is the trailer up position (motor should not be running).

***if the center button doesn't do anything at all, regardless of the position of the outdrive, it is the limiting switch on the port side of the outdrive that is faulty***

 

[bruceb58]

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

I hope you don't work on anyone else boats except for your own...
If you start any stringer or a mercruiser or a volvo with the impeller on the motor you can burn out the impeller long before the water can get there.

You may want a mulligan on this statement!

No problem using muffs on Volvos or Bravos which have engine mounted raw water pumps.

Curious how you think having water forced into the drive with muffs is any different, or worse for that matter, than launching your boat and then starting it.

 

[ihaveabrownboat]

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

OK, it sounds like you have an older mercruiser outdrive.
They are fine to start with muffs.
The 3 trim buttons are trim down (the bottom one)
trim up (the middle one), now this one will only go from the full down position to apx 30 deg. It is the upper limit of the drive with the motor running.
And when you press both "up" at the same time that is the trailer up position (motor should not be running).

***if the center button doesn't do anything at all, regardless of the position of the outdrive, it is the limiting switch on the port side of the outdrive that is faulty***

One of the buttons didn't seem to do anything at all. But your remark may help me fix that. Is the limit switch the little round switch on the rear of the boat? If so it's not bad. But it is brand new. It was the last thing the prior owner did before passing away. His son gave me a sheet with written instructions on how to adjust it. But he was sure that the adjustment itself had never got done yet.

The instructions seem straightforward enough. Hopefully doing that will bring back the switch function.

Am I correct in understanding that the up/out switch only works in conjunction with the other "out" switch and is used just to put the drive in the trailering position? So the switch marked "in" and "out" takes it through ranges of motion that are correct for the time its in the water?

The half that isn't doing anything right now is marked tilt/acc. That's what'll be dead until the limit switch gets adjusted?

 

[fishrdan]

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

When you lower the drive to hook up the muffs and start the engine, make sure the drive and prop clear the driveway about an inch. If they are really close and you hop in-out of the boat, they could contact the driveway. Not really a biggie with the drive's skeg, but a spinning prop meeting the concrete will make gawd awful sound... (Crank the trailer's tongue jack down if needed.)

Also, check the muffs often to make sure they haven't slipped. Or, the hose fitting hasn't popped off the muffs.

 

[four winns 214]

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

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.

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.

 

[BoatDrinksQ5]

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.

I watched the temperature and muff connection like a hawk my first time using them - the kind i got fit like a glove (pretty incredible) - they were the dual sided flow with the larger rectangular connections that were able to tilt vertically to perfectly fix over the vertical line of water intake on each side. Zero leakage once running with near full or full hose flow. TOok forever for the engine temp to come up.