Any guess about overheating problem?

[knotflying]

I'm curious... Where does the OBD II cable connect to on the engine as a search on all my Yanmar engine manuals for "OBD" shows NULL ?

On my R-27 the cable connection is in the engine compartment on the port side on the bulkhead wall towards the front.

 

[baz]

Thanks Mike... I will look for the OBD II connecter where you've described it to be.

 

[nzfisher]

Some folks who responded might be curious about the overheating problem. Yes, it appears to be the impeller, took it out along with the stair so I could get to it easily forevermore. It had 2 vanes left. Called and asked Ranger about the parts that must have washed into the system, (chamber is clean). They said they would probably be blown through. So now I am replacing the fiberglass stair with some hardwood designed to be easily removable so I can do front end repairs while on the water if necessary. Thanks for your help.

 

[knotflying]

I have been considering removing my fiberglass step on my R-27. Did you find that removing it made a significant difference in access? Did you remove the riser with the trap door as well or just the top?

 

[baz]

This is an interesting development in that the R-27 has a less inviting access to the rear of the engine compared to the R-25. On the R-25 the cabin step has a fullwidth lid and a forward riser that can be removed via 4 screws. This means on the R-25 access to the rear of the engine is quite favorable compared to what has been made standard on the R-27. This IMO is a 'step backwards' (no pun intended). With the R-25's cabin step lid open and the riser removed there's a large gaping hole to put a small child into... (just joking now)... but the point is the R-25's engine access is in this regards much better than on the R-27. Maybe the newer R-27's have a different access via the step... just dunno.

Accessing the water impeller and pulley and pulley belt is really quite easy on the R-25.

As a side note... during a recent cruise this past week I noted that my engine coolant temp stayed at a constant 188ºF no matter what RPM I ran the engine at. It simply never wavered from this temperature !

 

[Brian B]

Not the case in the R 25 SC, I will also be cutting that step out and fabricating a removable wood step.
The Yanmar tech who recently worked on my boat told me that future work on the front of the engine could cost twice as much due to the limited access. Time equals $$$$$.
Not the best design.

 

[nzfisher]

This is the solution to the overheating problem that I encountered sometime ago. Just thought I would post the "solution" so it is no longer a mystery. Thanks to everyone for there suggestions and help.

On the subject of impeller change. I had posted recently the the engine on my R25SC overheated. I did remove the impeller and all of the vanes except 2 were totally broken off/missing. I am lucky to have access to many boat mechanics, professionals, not just weekend guys where I keep my boat and their advise is free. They said that most likely the intake was blocked by something, weed, kelp, plastic misc. and caused the impeller to run dry. This will destroy an impeller in about a minute according to them. They also said that it is a good idea to get out all of the old parts prior to replacing. Not wanting to take too much of the engine apart, it is still a mystery to me how to get the metal cover off, I modified a tractor sprayer part to fit into the top zinc threaded hole in the block. I alternated filling this with water, then compressed air to blow out the cooling exchange system and recover the parts. After several, maybe as many as 20 iterations of both air and water I recovered all of the parts from a large piece of cheese cloth placed at the front end of the bilge. This saved me a lot of time and headache and is worth noting in case this happens to you.

Since I do use the boat in the ocean I have removed the fiberglass step and replaced it with a high density wooden step scribed to fit the old space so I have better engine access. I can now replace the impeller by myself in about 20 minutes and can probably do it at sea. In my mind an alteration well worth the trouble.