2006 Honda 225 Overheating problem

Hi guys,

I have a 2006 honda 225hp outboard I have been having trouble with overheating if I push the boat over 4000rpm - at 4000rpm it will run all day any faster and I am getting the single long beep overheating alarm and it is knocked into limp mode. I have twin engines and it is the starboard engine which appears to be overheating. Using a temperature gun I did notice the starboard engine manifold was hotter then the port engine manifold though off the top of my head I cannot remember the actual temp I was running.

To date I have
1. Replaced the thermistats
2. Replaced the impeller and impeller housing (old housing had a crack in it)
3. Reverse flushed from the thermistats and flushed with salt away product.
4. I have taken the large hose off the bottom of the manifold and checked for corrosion/build up restricting flow (there was a little though not a lot which I cleaned out)
5. I have bought the Dr Honda tool and software though admitedly I am not really confident in its use (I can see it has had overheats but don't know how to use it to find where/which sensor has registered these.


I am starting to run out of ideas... in the next few days I will replace the pressure relief valve and flush valves when i can get them in to ensure they are not causing the problem. If the pressure relief/flush valves don't sort the problem I will replace the large pipe on the bottom of the manifold just to make sure it isn't squeezing although I doubt this is the case.

One of the local boat dealers did mention flusing the engine with diluted hydrochloric acid which didn't seem like a great plan to me...

The only other thing I have played with was to replace all 4 batteries, a mate mentioned it was possible i didn't have a good connection which could also cause this type of fault though I am struggling to see how if it isn't happening throughout the rev range (Please correct me if I am wrong).

Any other idea's as to what could be going on??? I have been trying to tackle this for a while now and could really do with some advice...

Thank you for your time guys!

Rob

If you have the four-light key switch panel, does your red overheat light come on?

Have you pulled and cleaned the overheat sensors and terminals to each of the two overheat sensors on top of each manifold? Note that the engine also has a separate ECT (engine coolant temperature) sensor.

Have to pulled ECM codes using the method of shorting the service connector (lime green/white shorted to black - which has been described many times on this forum)? If so, do you get six blinks on your MIL light?

If you have the Helm shop manual, go through the diagnostics on the ECT starting on page 5-31.

Try this.. Drop the lower unit.. Tilt up the motor little bit.. Look for where oil pan meets cooling water pipe with o ring.
I normally use garden hose.. I put this water hose to cooling water pasages(after drop the lower unit)
turn the water on slowly..(works better with manual valve) look for water leak around oil pan and cooling pipe area.
.. We are honda dealer here so cal.. We have seen this problem alot on high mileage 225 on la harbor and port police motors..if u dont know what i m talking about.. I can send u a pic. So i can give u an idea where to look for.
if this is the problem. You need a gasket and new oil pan.

So for an update...

To date I have
1. Replaced the thermistats
2. Replaced the impeller and impeller housing (old housing had a crack in it)
3. Reverse flushed from the thermistats and flushed with salt away product.
4. I have taken the large hose off the bottom of the manifold and checked for corrosion/build up restricting flow
5. Replaced the L shaped water pipes on bottom/side of manifolds just in case they were having a bit of squeeze or contributing in any way (note there was a small amount of crud in here... though not a lot.
6. I have bought the Dr Honda tool and software though admitedly I am not really confident in its use (I can see it has had overheats but don't know how to use it to find where/which sensor has registered these.
7. I have cleaned and replaced the pressure relief valves and also the flow valve.

I have not yet tried the fix given above by Talklessridemore, have sent a PM yesterday so hopefully will recieve a photo!

It is likely completely unrelated however the one thing I did do prior to this problem presenting was to change all 4 batteries... is anyone aware of any way this could affect the motor causing an overheat or at the very least a sensor to get upset?

Next step will be switching the sensors between the engines... any further advice??? I am pulling my hair out a little on this one!

Rob

Fit check all of your pin connectors at the ECM. Before switching sensors, I would consider just switching ECM's to see if the problem goes with the ECM. If you eliminate that, then you are back to the sensors AND/OR wiring connectors.

Follow up:

Hello all, so an update on the situation.

The fix ended up being fairly simple - I ran a light acid flush (in this case using vinegar) through the engines water jacket. (won't go into this process as plenty of other threads have allready covered this.

This flush removed a considerable amount of lime scale, I then reverse flushed at as high a pressure as I couold with a garden hose with good result.

Engines are now working very well.

Thanks to all those who contributed to this thread, I hope this information will be helpful for anyone else out there who might experience a similar issue.

Cheers
DM

That's great to hear. Always try the simple things first.

Nice thanks for info