KAD 32 engine overheating

[barney365]

I have a Sealine S34 with twin KAD32's. I've recently had a problem on my starboard engine with overheating. I can run the engine at between 2-3,000 revs without issues. Temp stays in line with the Port engine. When I drop to idling the temperature will drop in the Port engine but remains high in the Starboard engine. The coolant level in the header tank appears to rise then starts pushing through the cap.

New impeller, cleaned weed off legs, checked and run engine without thermostats all tried and tested but to no avail - any ideas greatly welcomed.

 

[Peanuts]

Hi

First of all, have you had any problems before with temperature on this engine? Had any servicing done on it or has it just started to overheat or was it gradual increase over a space of time?

I stand to be corrected but on the S34 I believe the oil cooler is on the stbd engine, this would be my first point of inspection, it would normally have been the outdrive and the water intakes but you say you have checked those. Still on the outdrive I would then check the rubber hose to the transom for delamination, also check to see if the hose connection on the O/D is plastic (black) or aluminium. The metal ones corrode on the inside restricting the water flow.

Check the oil cooler, either remove it or if enough space remove the water pipes and rod the tubes in situ. Note if there is a lot of bits of shells etc afterwards this is probably the problem.

I think this is probably enough to be going on with for the moment, let us know how you get on and we will if required carry on from here.

Steve

 

[jparham]

Port engine supplies the calorifier, so is usually a few degrees cooler - worth knowing if you are trying to limp home as fast as possible.
Did the over-temp warnings sound? Think that's at 106deg.
Thermos wide open at 92 degC.
Usual places to look are:
Animals in the water intake at bottom of leg
kinked/delaminated water intake pipe between leg and transom
Animals in the lower pipe to bottom of raw water pump. This pipe is so hard it's difficult to figure out whether there are mussels in there or not.....
Calcified Intercooler
Calcified exhaust heat exchanger - Has the paint started to bubble on the top of the heat exchanger?

It's easy to take the top off the the intercooler to see what condition the tubes are in.
If it's calcified, you can assume the rest is.
Brick acid does wonders ;-)
Oh, and when you did the service, did you make sure the coolant was 50% diluted? Any stronger and it significantly affects its cooling capability.

 

[AdeOlly]

What's interesting here is that the engine cools okay at speed and only overheats when throttled back... to me this sounds like heat soak causing coolant to boil, it could be that you have a partial blockage on the freshwater side that is only apparent at slower engine speeds..... Just a guess...

 

[volvopaul]

Id say sticking thermostat to start with as its getting that hot its expanding the water and pushing coolant out, easy to remove stats and test.

Then go down route of raw water problems, has the system been bled of air since the new impeller was fitted, loosen strainer cap and let water flow out at tickover for a few seconds.

Its the oil cooler thats first inline so maybe there is some weed and shells in there, not an easy place to get to, take off supercharger to get at!.

Also if there has been an impeller failure the broken off blades can flow back in the line between the pump and the ps oil cooler, then they get sucked under the cam in the sw pump blocking up the intake.

Some clues there to get you going.