engine cooling water loss

[Birdseye]

Beta 20 with 900 hours has started losing cooling water. There is no rise in the oil level so it looks as if a head gasket failure is out. There is no water expelled from the header tank vent which also suggests that a head gasket failure is out. Indeed there is no evidence of water loss except for the lowering of the level in the header tank. So it seems to me that the first thing to investigate is the sealing of the heat exchanger - is hot engine coolant being ejected under pressure into the raw water flow. No signs of a failure of the calorifier - antifreeze appearing in the hot water

Only other issue is that the loss was first noticed mid winter with the boat out of use but after hard frosts. Did this loss occur before the boat was hauled out? Cant remember whether I checked after haul out - likely not.

So I am reasonably sure that the loss is down to the heat exchanger. Does this make sense to you?

 

[footsoldier]

I cannot fault your reasoning, certainly the logical suspect (although Murphy's law will sometimes come into play)

 

[Bilgediver]

Is there a chance that the coolant froze in the cold weather? Maybe you have a failed tube in the heat exchanger. This could be plugged at both ends.

 

[Aeolus]

Definitely check the heat exchanger first. I'd start by replacing the o-rings. They were the root cause when the same problem afflicted my Beta 20,

 

[Refueler]

I removed HE from my Perkins after the internal tubes collapsed ...

Prior to full collapse - all sorts of weird happenings with coolant ... at one stage - similar to OP's

 

[jane444blue]

I had this issue 2 years ago on my Beta 25. Over the season noticed the loss and monitored, c150ml over 10 hours or so running. Eliminated leaks each end of the HE, put a container under the overflow pipe to check that, nothing. That winter when servicing showed the HE to the engineer who realised it was twisted and damaged. It was v stiff the previous winter and I had been too rough getting it out. New one via engineer wasn't too costly and fixed the problem. I'm much more gentle tapping the new one out, but tbh it's not such a snug fit as previous one. Good luck

 

[Refueler]

The HE for my gearbox ... cools the oil that drives it ... also had tube failure as my engine HE did ....

I gave to a metals master - who took one look and reckoned it was shite ! It was the OEM unit - he reckoned the tubes were too thin and its lucky it lasted as long ..

He rebuilt using the old outer casing - reducing the number of thin small diameter tubes ... making it with less but larger tubes ..... with better volume throughput both of oil and cooling water .....

Works a treat.

I considered having him create an Engine HE - but to be honest ... having repiped and removed HE system ... decided to stay with raw water.