Engine help wanted please - KAD32 Alarm

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jimmertek

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Hi guys

Grateful for any advice here as I'm not an expert on engines.

I've got a Bavaria 300 Sport which up until now hasn't been too much bother. We have twin KAD32s. This weekend I checked water filters, checked impellers (by removing impeller cap and re-attaching cap) and replaced a pre-fuel filter. I checked oil levels etc - no issues found. On my next leg (canal use) my port engine alarmed and overheated. I checked the water filter, checked that fresh water was coming through (leaving lid off and starting engine = water everywhere!) and now pretty stumped after that. I've taken the impeller out and re-inserted it, it looks fine. Water filter cage also fine.

There seems to be slightly less air coming from the exhaust at the back of the boat on the engine that is overheating. However I cannot think what has changed which would make a difference. I also checked the air filter (metal can and re-attached it). Again, to no avail.

There is plenty of coolant, in face the coolant level seems higher in the engine which is overheating (does it expand when hot?).

Could this be a case of plastic bag entering the system and preventing enough water coming through to cool it? It overheats pretty quickly once it has cooled, re-starting the engine and even idling the temperature climbs from 40c to 90c in 5 minutes.

Also, the engine which is overheating, when I idle the throttle the oil / engine pressure dial drops back to 35/45 whereas the starboard engine which has no issues hovers on 60.

Grateful for any advice here! Thanks, Jim
 
Check (urgently...) coolant in oil or oil in coolant. A linked oil and coolant problem points to either a failure in the oil cooler (easy but not cheap I'm afraid) or head gasket (not easy and not cheap I'm doubly afraid). Over full coolant could be because it now contains oil too.

Be really careful - mixing oil and coolant can completely trash an engine if you keep running it.

There could be many other cheaper and easier overheat problems too, but check these to start to be sure you don't cause serious damage.
 
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Hi,

Thank you for the quick response.

How could I check this? What could possibly cause this?

Use is 4-5 knots canal use for 3 hours before the mooring up and then setting off again.
 
After stopping , allowing the engine to cool and restarting the engine does the issue persist ?
Sounds like you have picked up something, perhaps a polythene bag, on the intake. Sometimes stopping the engine will allow the obstruction to fall off.
 
KAD 32 , does the temp gauge show 95/100 degrees C ?
Or is it just the overheat alarm on ?
I won't type anymore until you answer as a KAD 32 should not overheat at canal speed.
 
rosssavage said:
Check (urgently...) coolant in oil or oil in coolant. A linked oil and coolant problem points to either a failure in the oil cooler (easy but not cheap I'm afraid) or head gasket (not easy and not cheap I'm doubly afraid). Over full coolant could be because it now contains oil too.

Be really careful - mixing oil and coolant can completely trash an engine if you keep running it.

There could be many other cheaper and easier overheat problems too, but check these to start to be sure you don't cause serious damage.
Click to expand...

KAD 32 has sea water cooled oil cooler so oil cannot enter the coolant closed circuit.
As the oil cooler has engine maintained oil pressure inside it and the sea water is at max3 psi the oil cooler will only leak in one direction = oil straight out into the sea very quickly net result a seized engine.

If head gasket had failed it would blow coolant straight out the coolant level bottle.

KAD 32 alarms are very temperamental and can set alarm off at 40 degrees C .
 
Alarm sensor is good at failing, good luck with changing it, not an easy job, check what temp is shown on gauge when alarm sounds, as said above already covers it all.
 
Hi all

Thanks again for prompt replies.

I can confirm definitely KAD32. At canal speeds (4-5 knots tickover). Alarm sounded, temperature showed 100C (at canal speeds). Some smoke from the engine bay and a very hot engine.

No signs of any oil in the canal and checked oil dip stick - normal levels.

Leaving the engine to cool to 40c then starting up again = same issue.
 
If you touch the face of the seawater pump (where you checked the impellor), is it hot or cold when running.
On mine, when I did have a minor overheat, the coolant level rises, so this a probably a symptom rather than a cause.

Belts all ok and properly tensioned?
Especially that small flat belt that drives the freshwater pump from the bottom crank pulley?
 
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How quickly did this happen from starting? Check if airlock in raw water system, as said above you need to check if pump is getting hot, this will confirm possible airlock.
 
I'd say about 10 minutes of idling in the quay an 20 minutes of canal speed tick-over before the alarm sounded. I never let the alarm sound again - I just watched the temperature gauge increase to 80/90 (which it never gets to for canal speed) and turned it off again. No more alarms or smoke but the overheating issue is definitely still here.
 
Thanks for reply. How would I check for an airlock in the raw water system and how could I remove it? Would this lead to the issue of less air exhaust bubbles in the problem engine too (although that could be a red herring - both engines are exhausting).
 
I'm reading lots of background threads. I didn't refill the strainers after checking the impellers, could this cause an airlock?
 
>>I didn't refill the strainers after checking the impellers, could this cause an airlock?
Yes, it could. On mine, the seawater pump plates were worn, and the pump didn't self prime.
You can tell if this has happened, because the face of the pump gets warm quite quickly, whereas it should be "canal cold".

As a temporary fix, you could take off the strainer top and pour in a couple of pints of water, then quickly put the top back on and try again.
If this works, you need to have the pump checked out: it could be worn. Maybe a new plate will help, or it could be the pump body itself.
 
Thank you - the face plate was pretty worn, I remember thinking that when taking it off, and it was 'shiny' in the middle around 10 pence piece size. Is it worth swapping the impeller (with grease?) and faceplate over from the second engine, filling up then trying again? I will keep my hand on the impeller face place to feel for temperature change, should it stay cold or warm up slightly given the pump moving?
 
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