I'm one step away from getting a mechanic
to come checkout the engine
- ! Hopefully I can get a few ideas from the masters on this forum.
I have a 2006 Yanmar
4JH4E with 800 hours on it. The boat was well taken care of - engines are super clean - previous owners were in their 80s and didn't use it much but took really good care of it. The one thing they said - the starboard engine
always ran hotter than the other.
So here is the story. We took the boat out for a sea trial and the alarm
went off for overheating
. We saw water
coming out of the exhaust
and let it idle for a few seconds before shutting it down. There was no steam and even though the gauge was pegged at 240, it didn't seem that hot.
On the list of things to fix before we took possession of the boat was this overheating
situations. Of course - we had the same problem again the first day when started our journey home from St. Pete to Key Largo
. We found the overheating alarm
only went off when we had the RPMs over 2,000. We also noticed that on the second day that we had to use more throttle at the controls for the same RPMs as the port engine - which wasn't the case before.
So we run the engine at lower RPMs (1,200 to 1,500) and had no problems until we needed her and went up on the RPMs and the alarm would go off. We get back home a few days later and I start to trouble shoot.
The owner's mechanic
looked at the engine after the sea trial and said that he pulled the impeller and it looked fine - checked the other normal items and everything checked out. I assume he didn't take her out or run it over 2k.
When I started to trouble shoot it the first thing I did was pull the impeller. I was so hoping this was the problem - but to be honest - it looked brand new. I installed a new one anyway and put the old one in the spare parts
bin. I then took off the hose going from the impeller to the block - started up the engine - water
came gushing out. I then took the hoses off the block to the exhaust elbow
(there are two hoses that go through a little gizmo on the wall - unsure what it is - but I am sure you guys do) and ran a hose through it - no problem - water streamed out. I then ran water upstream from the hose near the exhaust to through the heat exchanger
towards the impeller... crud came out - but nothing crazy - and water did flow through. I had the hose at 40% or so. Also dove on the SD and cleaned all the holes - there was a lot of growth in just 3 weeks.
I was hoping that a few impeller blades or something would shake free but nothing really came out that could have stopped it up - or at least it didn't seem substantial to me.
I cranked up the engine - some water came out but when I went back to idle - nothing. I had to turn the boat around and ran the engine - no water at all. The heat gauge didn't go past 120 so it wasn't that warm (flipped the boat around pretty quickly - 5 mins or so). Turned it off. Let it set for a few hours. Turned it back on - nothing.
Now I know the impeller is fine. I know the hoses are clear. I assume the heat exchanger
is good - but not positive. So could it be the thermostat?
Any ideas would be great! Sorry for the book....._steve