• 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

3.0L Merc running hot....sometimes

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


  • 3.0L Merc running hot....sometimes

    Hey yall, just pu the boat in for the first time this season and went for a warm up run. She ran great for a few minutes then I smelled something, checked my gauges and noticed the engine temp was well above 220. Figured I picked up some weeds on launch threw her in reverse and the temp came back down to 130. After running a cruise speed the temp would creep back up till I stopped and idled or threw it in reverse. After pulling into the dock I could hear water boiling in the block. Disconnected water hose from stat housing to impeller and I could blow thru it and also pulled hose to the water pump and lots of water poured out. If I was run the boat with the supply hose from the impeller off it should be a good stream of water coming out? Im guessing the impeller is shot but i think I will replace it and the stat. She ran good on the trairler with the muffs, plenty of water coming out the exhaust sat right a 130. Any ideas??? Btw it is a 1993 vip 3.0l


  • #2
    Re: 3.0L Merc running hot....sometimes

    Impellers need replacing every other year, period. It sounds like you are in need of one. It is a good idea to replace the thermostat regularly also. Sounds like you are on the right track. When replacing the Thermostat be sure to get the gasket that has the small eyelets in it so your temp gauge will work. Also while you have the drive up or off check the exhaust passage for parts of a flapper that could restrict the flow and also cause overheating.
    When will people learn that impellers require regular
    replacement and are not drive it till it pukes items?

    1984 Regal Medallion 195
    3.8 V-6 with the dreaded
    OMC Stringer Drive.
    2003 Avalanche w/Hypertech

    If it ain't fixable - don't break it!

    Comment



    • #3
      Re: 3.0L Merc running hot....sometimes

      Got the new parts but took her out for one more test run last night. Cruising around on plane at no more than 1500rpm temp stays at 130, get going any faster and the temp rises. Drop back down to 1500 r's and shes fine

      Comment



      • #4
        Re: 3.0L Merc running hot....sometimes

        Was there any vanes missing from your old impeller? If so, and you didn't find all the pieces, they could be partially blocking a passage. You may also have a faulty thermostat that isn't opening all the way, or even the water passages plugging up in the exhaust elbow and/or manifold.
        Don S.

        sigpic

        Please, no PM's (Private Messages) regarding boat/engine problems.
        That is what the forums are for.
        Only forum/moderator issues will be answered in PM's.

        Comment



        • #5
          Re: 3.0L Merc running hot....sometimes

          sounds like a blocked passage way somewhere or a stuck closed thermostat (more likely). if it was a bad impeller, in my opinion you would be overheating at low rpm instead of high rpm when water is forced into the motor.
          2003 Stingray 220LX 5.0L -- Alpha 1 Gen 2
          1977 Masterline 17' -- 165HP, 4.1L -- Alpha 1

          Comment



          • #6
            Re: 3.0L Merc running hot....sometimes

            I installed a new impeller and housing. The impeller didnt look to bad, a couple of wear marks there the housing grates are. The housing on the other hand had a ruff spot on about 1/3 the way around. I figure at low rpm it was pumping good water but a high rpm the ruff spot was creating a cavatation thus letting alot of air in. Just my 2c. Did also put in a new stat for good measure, looked like the factory original. Thanks for the help.

            Comment

            Working...
            X