• 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.
  • ALL iboats Forum Members and Guests:
    To show our appreciation for your participation in the Forums, we're offering an exclusive Forums-only discount good for an additional 5% off your iboats.com order for a limited time.
    To redeem, simply call our Customer Service Team at 800-914-1123 (Open M-F, 9am - 8pm Eastern Time) and mention the Forums 5% off discount. Offer excludes engines, trolling motors, and electronics.


Announcement Module

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.
See more
See less

1988 Shamrock engine problems

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

  • 1988 Shamrock engine problems

    We just moved down by the bay and the guy left a 1988 Shamrock 20ft with the house. The boat runs good but it doenst idle and it keeps over heating. Its got a 302 ford/pleasurecraft in it. Its a great boat but we keep having little problems with it. What temp T-stat do you guys run? What temp should this engine be running at? Were good until we get around 2500 rpms than we start having trouble. Chris

  • #2
    Re: 1988 Shamrock engine problems

    You need to give more info on engine and drive


    • #3
      Re: 1988 Shamrock engine problems

      Someone say BARNEGAT BAY?! You should post using the letters O.M.C. & Ford in your header. Pretty sure that's what you have, I don't know jack about O.M.C., but there are alot of guys here who do. Now the 302 Ford however.......J
      Disclaimer!: In my inexpert opinion......


      • #4
        Re: 1988 Shamrock engine problems

        is it fresh or salt water cooled? do you have any of the maint history such as seawater pump replacements and riser/manifold replacements?
        no tech questions by PM, they wont get answered.
        you have to be trusted by the people that you lie to .


        • #5
          Re: 1988 Shamrock engine problems

          Barnegat Bay is right. The impellar was just replaced. It only has 480 hrs on it. The manifold looks original or at least OEM. Its salt water cooled. What else would you need on the engine? ThanksChris


          • #6
            Re: 1988 Shamrock engine problems

            1988 Shamrock 20' were made in Cape Coral, Fl. Ford 302 - inboard -with deep keel - to protect prop in shallow coastal waters.Very popular in Southwest Florida. Engine conversion, was by Pleasurecraft. Overheating at high speed is a lack of water flow problem. If this is theboat that I think. What is the exhaust system from exhaust manifoldsto transom. They came from factory with 4" pipe. Are the manifolds center or rear risers? I owned a 1983.


            • #7
              Re: 1988 Shamrock engine problems

              The exhaust pipes or hoses are 4 inch. Im not sure if the manifolds are center or rear risers. How would we be able to fix the lack of water flow? What temp T-stat is right for these boats? What temp should these engines be running at? The boat is great but we just keep having problems with it overheating. Chris


              • #8
                Re: 1988 Shamrock engine problems

                I had one of those boats,my last one,Great one at that.The engine had a 160 drg t-stat in it.After running it for about 8 years,I had repower it with a 351 Marine power bobtail engine.At the time it cost me around $4,800 for the engine.What a big improvement on how the boat handle.Went from 12 gals gas per hour to 7 per hour,pick up 9 mph at 3300 rpm's,prop pitch was 13x13 went to 13x19.WOT speed was 47mph loaded,cruise speed was 36mph @3300rpm's,reading were use from a GPS.The problem was it wasn't big enought for the family,now I am looking to down size due to the kids are out of the house.


                • #9
                  Re: 1988 Shamrock engine problems

                  Damn, our boat hits like 33 at around 3400. Yours had a bigger engine but still thats a big improvement. This boat is great because of where the engine is. Its right in the middle of the boat instead of in the back like an I/O. Thats the great thing about an inboard. The engine was 4800. With an I/O the engine would be 4800 and the out drive would be another 5000. What size Shamrock did you have? We're running a 165 degree T-stat now. ThanksChris


                  • #10
                    Re: 1988 Shamrock engine problems

                    Engines that used freshwater to cool the block used a 143 degree thermostat. But problem does not sound like a bad thermostat but a water flow problem. The engine should have center dump risers and they should use 3" inside diameter hoses. Idle problem could be a adjustment on the carb or it may need to be rebuilt. First thing to check on the cooling problem is to check the trans cooler for seaweed clogging the tubes. then check your impeller to make sure it is not damaged, if it is damaged it is the sherwood part number 9959k and it should have all the gaskets you need. Then go to the thermostat housing to see if it is blocked or not flowing right. then check your exhaust manifolds for restriction in the cooling passages then you will want to check your exhaust hoses and mufflers if equiped for loose or broken baffles.