Logo
Click for Honda Manuals, Parts and Model Guides!
Results 1 to 14 of 14
  1. #1
    Join Date
    Nov 2018
    Location
    San Juan Islands, WA
    Posts
    79

    Default 225 Running hot at high RPM

    Port: 225-AK3 418 hrs
    Starb: 225-AK3: 851 hrs

    Just did 400hr and 800hr services on these motors about 10 hrs ago. The 800hr service included valve adjustments, internal anodes, water-pump etc.

    The starboard older engine has occasionally been a degree or two hotter than the port, but when running at cruising speeds (4500 rpm) - it often settles out to be shockingly identical (to the 1/10 of a degree). Today, I was running them at WOT for a while - maybe 10 minutes - and noticed the biggest temperature gap I have ever seen. Port was running at 210.2f and Starb was 221.0f. No overheat alarm.

    A 10 degree difference seems troublesome, both motors were peeing strong and stream felt nice and cold.

    My immediate thought goes to the work I did on the internal anodes on this motor as it was a painful extraction of vacuuming & dremmeling to get them out. Not sure if a tiny fragment of dislodged anode could cause an issue - I would have thought worst case it would block the pee-stream passages as those seem the smallest.

    Anything else I should be thinking about?
    Last edited by brettmarl; 09-26-2021 at 10:44 AM.

  2. #2
    Join Date
    Nov 2018
    Location
    San Juan Islands, WA
    Posts
    79

    Default Re: 225 Running hot at high RPM

    I should add that T-stats were replaced with new and also that the temperature I'm talking about is as reported by NMEA not by Dr Honda. Not sure if there are more sensors that Dr Honda would see (eg. left/right side) - but I could hook that up if need be.

  3. #3

    Default Re: 225 Running hot at high RPM

    If telltale stream is cold/cool, I’d say you have a measurement problem not an overheat problem. I’ve had my 130 shut down and the telltale was quite warm. I would also guess that a 10f variation in engine temperature between the 2 is not really abnormal. Manufacturing tolerances can see that much deviation.

    Hopefully some 225 experts will show up to give additional advice.

  4. #4
    Join Date
    Sep 2008
    Location
    Hague, Virginia, USA
    Posts
    5,055

    Default Re: 225 Running hot at high RPM

    When you pulled the 400 & 800 hour service, did you change just the water pump impellors, or the entire water pump?

    If just the impellors, then that might be the problem. The liner that the impellor seals against can become worn and out of round. That could easily account for the difference in temp's.
    CHawk 25 DLX

  5. #5
    Join Date
    Nov 2018
    Location
    San Juan Islands, WA
    Posts
    79

    Default Re: 225 Running hot at high RPM

    Did the whole water pump kit including the housing and plate. I did not replace the seals below it as it pressure tested fine.

  6. #6
    Join Date
    Sep 2008
    Location
    Hague, Virginia, USA
    Posts
    5,055

    Default Re: 225 Running hot at high RPM

    OK. That's good.

    Block temp (ECM) should stay in the range of 194 - 212F, depending on the temperature of the water you are running in. Alarm should sound at around 230F. So, assuming your NMEA reading is correct, you are on the edge. You are probably still good for a while, but monitor closely. A good long run at higher rpm's may help the issue.

    When you pulled the T-stats, was there much corrosion below the T-stat seats? What about when you pulled the anodes? Much corrosion there? If so, that would be an indicator that you have corrosion build up throughout your cooling passages and a good treatment with Salt-A-Way, or similar, may be called for.

    That's about all I can think of.
    CHawk 25 DLX

  7. #7
    Join Date
    Nov 2018
    Location
    San Juan Islands, WA
    Posts
    79

    Default Re: 225 Running hot at high RPM

    Tstat seats looked fairly normal for annual change. A little build up but came
    off easy. When I pulled jackets to swap internal anodes I was expecting more gunk in the jackets but surprisingly clean given I’m in salt water and on buoy 4mo of
    summer with no flushing. Rest of the year I’m in a brackish marina and can fresh water flush after each run. Average water temp here is 55 degrees maybe 60 in summer.

    The little anodes in the jackets weren’t too bad - but the internal anodes with the big hex head were rough - I created a thread on it to get help extracting. Ian said they are always rough and hard to get out.

    next time I’m on the Trailer I’m going to try a more aggressive de-salting flush.

    i don’t like that I didn’t see those temps before the service -
    so seems related vs gradual salt build Up.

  8. #8
    Join Date
    Sep 2008
    Location
    Hague, Virginia, USA
    Posts
    5,055

    Default Re: 225 Running hot at high RPM

    Roger that. I'm out of ideas. Hopefully others will chirp in....

    Still think a good long run at higher rpm's may help the situation, but that is pure speculation.
    CHawk 25 DLX

  9. #9
    Join Date
    Nov 2009
    Location
    temecula, ca., usa
    Posts
    3,960

    Default Re: 225 Running hot at high RPM

    Just remember that NEW stands for:

    Never Ever Worked.

    I've seen many "new" tstats that were defective right out of the box.

    Just sayin'.

  10. #10

    Default Re: 225 Running hot at high RPM

    A quick sea trial without thermostats?

  11. #11
    Join Date
    Nov 2018
    Location
    San Juan Islands, WA
    Posts
    79

    Default Re: 225 Running hot at high RPM

    I’ve had a stuck tstat before and it usually manifests as an overheat alarm fairly quickly after getting into 4000 rpm range. Guess it can’t hurt to eliminate though - I have spares I can swap them real
    quick.

    although won’t be doing any WOT testing for a while. Forecast calls For 4-6 ft seas for a few days

  12. #12
    Join Date
    Apr 2018
    Posts
    1,578

    Default Re: 225 Running hot at high RPM

    Check your manifold drains, that's the large 90 deg rubber tube at the bottom of the manifold that drains into the mount case. Remove them completely and make sure they are clear. If they are okay, run 50deg thermostats, that is 19300-ZY6-003.

  13. #13
    Join Date
    Nov 2018
    Location
    San Juan Islands, WA
    Posts
    79

    Default Re: 225 Running hot at high RPM

    @ian - remember this thread? This is same engine / same service window. Is that what you mean by the manifold drain? I did end up putting a new flange in but could have messed something up.

    http://www.marineengine.com/boat-for...haust-Manifold

  14. #14
    Join Date
    Apr 2018
    Posts
    1,578

    Default Re: 225 Running hot at high RPM

    I'm.referring to number 8 in that parts schematic. If everything appears clean, use the thermostats I mentioned, I've done this often with good results. A lot of these motors run a little hot when they get older after extended salwater use.

Similar Threads

  1. High RPM Running Issues
    By Gracing76 in forum Mercury Mariner Outboard Forum
    Replies: 4
    Last Post: 10-13-2016, 06:40 AM
  2. 1968 9hp running high
    By Cncquinn in forum Ted Williams Outboards
    Replies: 0
    Last Post: 07-23-2013, 06:20 PM
  3. High rpm not the same when running
    By Floatation Device in forum Mercruiser Sterndrive Forum
    Replies: 9
    Last Post: 05-28-2010, 09:18 AM
  4. RPMbs running high
    By onewei364 in forum Honda Outboard Archive
    Replies: 1
    Last Post: 03-24-2008, 05:51 PM
  5. 98 150 Engine running rough after high mid to high speed
    By ken88 in forum Johnson Evinrude Outboard Archive
    Replies: 1
    Last Post: 10-15-2007, 02:32 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •