Sealine 310 kad42's overheating

[robdorling]

Hi guys

Im Rob and im new here and a novice marine engineer (very novice)

My port engine was running a little hot (over 80) so i checked a few things and found a cracked but intact impeller so i changed it and run out for approx 2 hours and all was fine , I moored for a couple of hours and 10 minutes along it reached 90 degrees so i shut it down and checked and the pump housing and stariner pot was very hot , upon inspection it appeared that the flow to the pump was restricted so i filled the system with water and run it up and has been fine since and running dead on 80 degress !! i am going to change the impleller again as ive beenm told any lack of water and heat can damage them !! , My starboard engine on the other hand appears to run cool around 60 degrees , Is this normal ??

 

[Peanuts]

Rob

Welcome to the forum.

Regarding your overheating problem, my first check would be the outdrive - water intakes. Check they are clear.
Most Sealines have their hot water tank plumbed in on the stbd engine that is why they normally run cooler but mine does not run that cool. Has it always done that?

On the plane both are normally around the 80'ish mark.

Hope that has not confused you even more.

 

[spannerman]

You could try disconnecting the inlet hose on the seawater pump and connecting to a water hose and try backflushing, if this doesn't help then you have to go deeper, I have seen mussels up in the water channel in the drive which requires drive off and splitting to clean out. Or it could be in the S hose between the drive and ransom, or it could be in the power steering oil cooler (down on the port side near the starter motor) if there is one fitted on that engine.
You just have to work backwards through the system until you fine the restriction.

 

[Greg2]

I have KAD 42's and the running temp can vary a little depending upon conditions. The manual says they should normally be between 75 and 90 so at 80 the port engine wasn't hot and your temp after changing the impeller wasn't an overheat.

A couple of points worth bearing in mind when dealing with engine temps:
- It is not uncommon for the gauges to give a slightly inaccurate reading (a laser temp gauge directed at relevant parts of the engine will help show if this is the case).

- As already mentioned one will have a different 'temperature profile' than the other due to the calorifier being plumbed to one engine

- When the raw water has drained from the pump (e.g. because the impeller has been changed or the strainer lid removed) it is wise to check on first start up that the water is flowing as it should. Simply touching the plate in front of the impeller will tell you if all is okay i.e. if it is warm then the pump hasn't self-primed and if it is cold to the touch everything is fine. If it is warm simply crack the strainer lid open a touch until water seeps out and then tighten and check the plate again.

I wonder if the symptoms you describe were as a consequence of a slightly lose raw water strainer lid? In such circumstances the pump may self-prime but when the engine is stopped the water could drain away and on the second start the pump fails to self-prime. May be off the mark but worth mentioning.

 

[robdorling]

Thanks guys

Both the pump cover and strainer pot were very hot but this was thee hours after I changed the impeller which at the time I made sure was primed and continued to check it during the run but I fear it could be a blockage !!