KAD43 Overheating South Wales

[crown22]

Starboard engine Sealine S34 overheating.Outdrives fitted.Impellor suspected but no pieces found in strainer.Housing slightly warmer than port engine ninety minutes after shudown. Any suggestions welcome.Thanks Stephen

 

[BruceK]

This could be many things but lets start with the most likely.

Firstly verify with a infrared thermometer pointed at your thermostat housing and verify that the reading you are getting is the same as the temp gauge. Any voltage drop will give you a higher reading at the gauge.

Get a couple meters of clear pipe, undo the pipe that attaches to your exhaust riser from your heat exchanger and run the engine very briefly. (you do not want to run for long and burn out your exhaust riser bellows)
If you are not getting a good stream of water you will need to chase back all the way to the outdrive for blockages and calcium / salt buildup etc. or raw water pump failure. Check raw water pump for sidewall and cam wear.
Look for air bubbles. The outdrive plastic hose flange that feed the raw water system can be fragile and leak air if damaged. This becomes a problem particularly when on the plane as it sits above the water then

If good remove and inspect the exhaust riser for rust blockages. THis is a maintenance replacement part.

If good remove the thermostat housing and thermostat plates and start the engine. You should see good and vigorous coolant flow from exhaust manifold down to coolant pump. If not send pump in for servicing. (dont worry it wont blow out everywhere).
Check thermostats open. one at 80C and the other at 85C

If all checks out give the raw water side a clearout with Rhydlyme and if you are still having problems then its of a more serious nature. Either that engine is having air fuel problems (Pump, Injectors, turbo or after cooler) (worn turbo can cause overheat) or the other engine is lagging causing this engine to work harder. At this point I would suggest you get a competent mechanic in though. Good luck. Simple engines, the fault should be easily rectifiable

 

[crown22]

Thanks Bruce Regards Stephen

 

[crown22]

Thanks Bruce Regards Stephen

Hi Bruce sorry it's a KAD41 but I suppose the diagnosis is the same?The sailing yacht I used to own had the exhaust and used cooling water exiting above the waterline so diagnosis was easier.Not sure why the S34 doesn't do the same?

 

[BruceK]

No such thing as a KAD41. Do you mean AD41? If so the principle remains the same except I am not 100% sure of the raw water route but expect it to be similar. Also I do not know for sure if you will not lose a lot of coolant with the thermostat housing cover and thermostat plate out. Try and be ready to switch off quickly if it does.

 

[Momac]

A friends ad41 sudden onset overheat on both engines seems to have been cured by fitting the old removed impellers. The new VP impellers had only done a few hours. Wondering if the new VP impellers are in some way defective although I understand they look okay. He has also reversed the brass face plates but it's uncertain whether wear on the face plates is a factor.

 

[Rickard]

Check the water/circulation pump. Sometimes the shaft brakes. Then the motor will overheat after a while on low rpms. Very fast when going to higher rpm
Remove belt and spin it it. If ít spins way to easy the shaft is broken

 

[alt]

Check the water/circulation pump. Sometimes the shaft brakes. Then the motor will overheat after a while on low rpms. Very fast when going to higher rpm
Remove belt and spin it it. If ít spins way to easy the shaft is broken

+1

Just to confirm, referring to the COOLANT circulation pump. On one of my KAD300's the shaft sheared. So no coolant circulating. From the outside, you would be none the wiser.

I bit the bullet and replaced the whole lot (wasn't cheap) rather than rebuild.

 

[oldgit]

Have frequently turned round the face plates on 40 and 41 series engines in the past, one or two seriously worn.
Despite the engraved lettering , worked perfectly well, with absolutely no problems at all afterwards regards cooling .

 

[crown22]

Thanks Guys sorted now by a great guy called George from Dale Sailing Neyland.It was just the impellor which had only done about 30Hrs.One of the vanes turned up in the strainer about 5 Hrs running later and the whereabouts of the other is still a mystery.Thanks again Stephen

 

[Seastoke]

How does it get in the strainer, the strainer is before the pump, I think

 

[crown22]

The strainer is after the pump as far as I can see.The engineer said that one might be thrown out backwards.Did Milford to Pwhelli and on without any further issue

 

[oldgit]

Thanks Guys sorted now by a great guy called George from Dale Sailing Neyland.It was just the impellor which had only done about 30Hrs.One of the vanes turned up in the strainer about 5 Hrs running later and the whereabouts of the other is still a mystery.Thanks again Stephen

"The engineer said that one might be thrown out backwards." H,mmmm

Think the first port of arrival on the 40/41 for any detached bits of impeller is the oil cooler. ?
Depending on access, removal of entry pipe from raw water pump to oil cooler can help to recover any missing bits.
A finger can help to dislodge any reluctant bits and popping a mains water hose pipe into the oil cooler orifice, has in the past , flushed out the remains of at least a couple of previous impellers.
Curiously the running temperatures were not greatly affected.
On older engines great care needs to exercised before dismantling the oil cooler, the alloy body tends to become one with the bolts holding it all together.
.


There are companies out there which will weld and refurb corroded oil cooler casing if they have something left to work with.

 

[SP2]

Thanks Guys sorted now by a great guy called George from Dale Sailing Neyland.It was just the impellor which had only done about 30Hrs.One of the vanes turned up in the strainer about 5 Hrs running later and the whereabouts of the other is still a mystery.Thanks again Stephen

George is indeed a "great guy".

 

[crown22]

Thanks "oldgit" I have tried to find a schematic showing the path of the water from the sea into the engine and back out again but have failed.Will keep looking.Thanjs again Stephen

 

[oldgit]

used to be several exploded parts diagrams online from parts VP dealers showing the pipes going from water filter to raw water pump and then to oil cooler.
Seem to recall on all my rather ancient engines it was a rigid copper pipe sealed at the joints by "O" rings and real PIA to make everything watertight after any disturbance .
Praise the Lord and a dollop of silicone sealant. Not to much mind, it gets everywhere.