Welcome Guest - Sign Up today
Welcome Guest - Sign Up today
Store Links Mobile - Shop Now

Announcement

Collapse

Help Tip: If you have a question that has not been answered to your satisfaction in the archives, it is always best to start a new thread of your own. By starting your own thread, you will receive the maximum number of views by forum members.

Below are some additional forum policies in hopes of all iboats members will follow, Thank you.

1. Please do not reply to old topics or hijack existing topics. Old topics of a technical nature are like a library book, Please do not write in them.

2. Old topics should be considered archives and used for reference only. Please do not reply to them.

3. Do not take over someone else’s topic (aka hijack) with your own question, even if it is similar. If you have a question that has not been covered to your satisfaction in the archives, it is always best to start a new topic of your own.

4. If you have a question for the original poster (OP) and the topic is over 30 days old, send the OP a PM, he may not even visit the forums any longer, or may not notice your question in the old topic.

5. By starting your own topic, you will receive the maximum number of views by forum helpers that may not even notice your question when it’s posted at the end of someone else’s topic. And those answers will be specific to your particular issue.

6. Please do not post to topics that have been inactive for more than 3 months unless you are the original poster. We have very active forums and any topic that remains inactive for that long should be considered "dead". It is especially confusing when there is an entirely new question posted to an old topic.

7. Posting at the end of any topic is considered to be hijacking the original posters topic which in turn subjects the topic to be closed if it continues to happen thus not making it fair to the original poster in the future had for some reason he/she needed to return for additional information or provide an update of the problem solved which is always welcomed within a reasonable amount of time frame.

8. Please note that you should see a red banner pop up near the bottom of each inactive topic asking you not to reply to old topics. The Red banner will read: Please note this topic has been inactive for 90 days. For the best results, please start a new topic.

Thank you all in advance for doing your part in helping iboats run a smooth ship.

Additional forum rules linked below.
http://forums.iboats.com/forum-rules-guidelines-405/
See more
See less

thanks and muff question

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • thanks and muff question

    Even though I just joined (so I could start participating and ask questions), I have been referring to this forum for a long time while shopping for a used boat again.
    Any time a seller said there is something wrong with his boat for sale, I would type in a google search. This forum was usually at the top and even when it wasn't, it has always been the best resource.

    Eventually, I just started referring to this forum to get answers first, without the google search!! Thanks for all of your time and efforts to everyone who participates!

    Question: I was reading somewhere a couple of months ago about muff use on some forum, don't remember which one.
    Someone said to never use muffs for more than 45 seconds and never exceed idle.

    I never knew this and in 35 years of boating, I have never had a problem breaking these "rules". Have I been lucky or is that bad info?

    thanks again !!

  • #2
    I imagine it would be very difficult to run tests etc. on an engine if you were restricted to running on muffs for only 45 seconds. Apart from that, you would often/usually need to get the engine up to normal running temperature, which is never going to happen in 45 seconds. How else do you check normal idling operating temperature, choke operation. Admittedly, some tests, by their nature must be run on the water, under load. Otherwise it's muffs. Provided you have a sufficient water supply I can't see any issues.
    ​I might have occasion to give the throttle a little "dart" but I wouldn't rev it up constantly and I think the usual recommended max would be 1500 rpm's on muffs, but I may stand corrected on that.
    1990 Wellcraft 250 Sportsman. Mercruiser 5.7

    Comment


    • #3
      I think the Mercruiser recommendation is 1500 RPM max. If you go much above that, you have problems getting enough water through a normal hose at city water pressure, and you revving the engine above 1500 can collapse your hose as the pump tries to pull water faster than the hose can deliver.

      You can run it as long as you like on muffs. Mine will get up to operating temp on muffs, but it takes a while.
      Location: West Central Illinois, USA 1997 Larson 186 SEi Bowrider I/O Mercruiser 350 #0F747565 Mag Alpha One Gen II #1A270120 Transom and Deck Restoration Project on my '97 Larson Bowrider

      Comment


      • #4
        Sounds like nonesense.
        As mentioned. As long as it's getting cooled, it's fine. I wouldn't be revving it much though.

        Comment


        • #5
          Ayuh,.... So long as yer supplin' more water to the muffs than the motor can use, it'll run Forever,....

          Really no reason at all to rev the motor over 1500 rpms on the muffs anyways, except to make noise,....

          Comment


          • #6
            Can't tell you how many times I've run on muffs for a half hour. Temp gauge never moves out of the safe zone. The one exception is a 5.7 Volvo Penta I owned. Temp gauge would slowly rise above normal if I ran it too long, but again, I'm talking 20 minutes or more. I could run my Alphas all day on muffs if I wanted to.

            My .02
            John and Linda
            Long Island, NY
            Escapade III
            1992 Carver 26 Command Bridge
            Twin Merc Alpha 4.3 'Gen +'

            Comment


            • #7
              Originally posted by JoLin View Post
              Can't tell you how many times I've run on muffs for a half hour. Temp gauge never moves out of the safe zone. The one exception is a 5.7 Volvo Penta I owned. Temp gauge would slowly rise above normal if I ran it too long, but again, I'm talking 20 minutes or more. I could run my Alphas all day on muffs if I wanted to.

              My .02

              On every alpha I've owned, the hose is supplying quite a bit more water than the engine will take. No matter how well the muffs fit, once you have water pressure and the engine is running, there will be water spraying out by the muffs.

              Comment


              • #8
                Did it again yesterday when I winterized the engines. 10 minutes to come up to operating temp, then another 15 minutes to give it a good flushing. Zero issues, and like Smokingcrater said, there's always water spraying out the sides of the muffs.

                My .02
                John and Linda
                Long Island, NY
                Escapade III
                1992 Carver 26 Command Bridge
                Twin Merc Alpha 4.3 'Gen +'

                Comment


                • #9
                  Sign up today
                  One thing I noticed:
                  I had to get a new set of those dual inlet muffs and they seem to be making the rubber stiffer and harder than it used to be. When running my Cobra on the hose it did not prime as well as before. I switched to the Merc/Quicksilver ones with the steel rod/clamp that goes through the water intakes and holds both halves tight to the lower unit. These cost more but seal better.

                  For those with Volvos and Bravos I came up with a little trick to get the impeller to prime faster and reduce wear on the impeller, used it on the Cobra and it works great:
                  Hook up your muffs and hose but don't turn on the water yet.
                  Get a funnel, water container and a screwdriver.
                  Go up the the front of the engine and disconnect the raw water intake hose at the impeller housing (V/P or Bravo) or thermo housing (Alpha or Cobra)
                  Put a funnel in that hose and fill it with water till you hear it leaking out around the muffs. Then re connect that hose & turn on the water. This will allow the impeller to prime much faster ESP with engine mounted impellers, because water will get to it quicker. It will fill that hose, and the water passage in the drive and the muffs & hose. Impellers can't suck air too well but suck water very well.
                  Last edited by Lou C; September 26th, 2017, 11:12 AM.
                  1988 Four Winns 200 Horizon
                  4.3 OMC Cobra

                  98 Jeep Grand Cherokee 4.0 Selectrac
                  07 Jeep Grand Cherokee Limited 5.7 Quadradrive II

                  "While air doesn't freeze....rust never sleeps"

                  Comment

                  Working...
                  X