• If this is your first visit to the iboats.com Boating Forums, be sure to check out the FAQ. To post a question or comment, begin by signing up. To start viewing messages, select the forum that you want to visit from the selection below.

Announcement

Announcement Module
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 threads or hijack existing threads. Old threads of a technical nature are like a library book, Please do not write in them.

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

3. Do not take over someone elseís thread (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 thread of your own.

4. If you have a question for the original poster (OP) and the thread 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 thread.

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

6. Please do not post to threads that have been inactive for more than 3 months unless you are the original poster. We have very active forums and any thread 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 thread.

7. Posting at the end of any thread is considered to be hijacking the original posters thread which in turn subjects the thread 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 thread asking you not to reply to old threads. The Red banner will read: Please note this thread has been inactive for 90 days. For the best results, please start a new thread.

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

what makes an engine knock?

Page Title Module
Move Remove Collapse
X
Conversation Detail Module
Collapse
  • Filter
  • Time
  • Show
Clear All
new posts


  • what makes an engine knock?

    i have a motor that sounds like its nocking... what exactly is doing the knocking in the motor. if i took it apart to fix the knock, what would i have to repair or replace


  • #2
    Re: what makes an engine knock?

    Need a better description. It could be anything..Poor fuel, bent or stretched connecting rod, bad wrist pin, wrist pin bearing, crank bearing, cam bearing, piston slap, etc, etc,....

    Comment



    • #3
      Re: what makes an engine knock?

      it sounds like a knock and i just wanted to know what is required to stop the knock. its in a motor that parts are no longer made for, and 84 tohatsu... it knocks cause it was overheated by previous owner, i have since fixed the cooling problem and now it starts and runs easy and pumps and shifts, but it now knocks... too little too late, huhthanks

      Comment



      • #4
        Re: what makes an engine knock?

        Could be alot of things. What grade of fuel are you using? You might want to try premium. It also could be carbon buildup - decarb. Another thing could be the wrong spark plugs or too far advanced timing.

        Comment



        • #5
          Re: what makes an engine knock?

          you can hear the insides of the motor pounding against something in there, its pretty loud.... i knw its not the fuel, im using 89 octane with 50:1 synthetic oil mixture. i also know its not ignition timing. its a tohatsu, and the older tohatsus, the ign timing wasnt adjustable.id like to keep the engine, as it starts perfectly, but parts are no longer made for it any more. if i tear it down to inspect the insides, will i be able to tell if something was ou of whack? or if something is shot.......?im really afraid to do this as nothing is made for this motor any more and if i take it apart i wont be able to get new rings or bearings for it if need be.. or can they be made by wiseco or somebody, do i NEED to use oem rings? and can bearings be made by somebody else? if need be

          Comment



          • #6
            Re: what makes an engine knock?

            Topic: what makes an engine knock?
            When it's cold outside and you have the door locked.

            Comment



            • #7
              Re: what makes an engine knock?

              Compression readings???And you said "if i tear it down to inspect the insides, will i be able to tell if something was ou of whack? or if something is shot.......?" Ahhhhhhh if you see a broken rod-------------

              Comment



              • #8
                Re: what makes an engine knock?

                compression is an even 130 per cylinder, starts first pul, idels well, pumps water and runs cool to the touch for about 5 seconds....?

                Comment



                • #9
                  Re: what makes an engine knock?

                  The problem is you need to take this engine apart to find out whats wrong and you can't do this because you can't get parts. Even if you find that its just a squirrel caught in there you will need gaskets and what not to reassemble it. More likely you have a bad bearing or wrist pin and you won't be able to reassemble it. Are you sure you can't get parts? Don't they still make Tohatsus? All you can do if no parts are available is look for squirrels banging garbage can lids in there and hope for the best

                  Comment



                  • #10
                    Re: what makes an engine knock?

                    they still make tohatsu's, yes, but they do not make the m8a anymore, nore do they make ANY parts for it at all... only option is if a dealer has had the parts on the shelf for last 20 years, they stopped making the m8a in 1985, and switched to the m8b in 1986 and on... i didnt know this untill after i bought the darned paperweight

                    Comment



                    • #11
                      Re: what makes an engine knock?

                      You could tear it down and part it out on eBay. Your good parts should bring a good price if they are hard to find.

                      Comment



                      • #12
                        Re: what makes an engine knock?

                        Just a suggestion-Give Twin City Outboard a call. They specialize in obscure and hard to get outboard parts. The web site is twincityoutboard.comThey have a giant bone yard of old uncommon outboards. They also have access to lots of after market and new parts. They would be worth a try. I know the m8a has been gone for a while, but it is not that uncommon. Good luck!

                        Comment



                        • #13
                          Re: what makes an engine knock?

                          i have tried and they said notihing is availableanybody wanna buy a 8 horse paper wieght?

                          Comment



                          • #14
                            Re: what makes an engine knock?

                            or anchor, I couldn't resist. I don't live to far from twin city outboard and if they can't help you i don't know where else you could go.

                            Comment



                            • #15
                              Re: what makes an engine knock?

                              Run it 'til it grenades, then part it out.c/6Hooty

                              Comment

                              Working...
                              X