Lost coolant

[Mike Fox]

Have a Yanmar 4JH3E 56bhp engine in Feisty, with fresh water cooling.

 

Last weekend, the reservoir was empty (first time ever!) when taking guests out, so I filled it, and thought nothing more of it. Had engine alarms going off before getting to the bridge, cleared a small and new ball of weed from the raw water strainer and limped back into Cobb's with a couple of forced stops, and the alarms went off again as I arrived. 

 

I couldn't find what was wrong, as the reservoir level stayed the same and raw water was being pumped around the engine. Interestingly there was no hot water.

 

Purbeck Marine make a quick visit one evening, and they couldn't find a coolant leak on the engine, proved there was no engine seizure, and even when the now empty heat exchanger was refilled, there was no obvious leaking. Running the engine in tickover and under some load made no difference. All pipes and joints seemed intact, and no visible leaking around the engine.

 

Some corrosion at the calorifier (hot water tank) was seen, and some slight dampness there might have contained antifreeze...so a possible leak.However, this is bonded to the hull away from the engine compartment, and the interior of the boat has been built up around it, and it will be a nightmare to even reach, never mind remove and replace. The lack of hot water implied no hot coolant reached the calorifier, but in itself wasn't evidence this is where the leak is.

 

Purbeck fitted pressure gauges yesterday, and in a quick 10 minute "cold" test, no drop of pressure was recorded, so it was left in situ, and pressure dropped away after several hours, confirming that if a leak is there, it's slow with a cold engine. They'll do more tests next week, and isolate the calorifier, and test the engine without, and then the calorifier without the engine, to narrow it down.

 

If it is the calorifier, then it can be isolated from the cooling circuit, and the engine still used, but if it's the engine, it might have a serious problem. Either way it feels like an impending "ouch"

 

So, no boat this weekend, and currently no absolute evidence what the problem actually is.

 

Anyone think of something simple it might still be, or any easy checks that could still be made?

[Kingfisher 126]

Hi Mike

 

I had a similar problem and it was the heatexchanger cores scaled up.

Pressure cap would release when under way and nothing would happen if run up on pontoon.

Took it a part and descaled and sorted it.

Good luck with tracing problem, but may be worth checking.

[Rob]

We had a leak on a water pump on a car, but only when a full temperature would it leak from the seal around the pump.

 

So it was fine on short trips but after a long trip the coolant level would drop.

 

Again, running on the drive, fine, until I left it to run until the fan came on, bingo, a tiny leak around the water pump seal, as soon as the engine cooled a little the leak stopped.

 

Sounds like purbeck have sensible plan.

 

R

[Brian]

Another vote for blocked heat exchanger.

A boat I used to have the use of in exchange for maintenance had the same problem.

Under load it got hot enough for the cap to vent, therefore coolant disappeared with no apparent leak.

[Jim]

Obvious question, but your engine oil isn't creamy is it ?

 

Or does the exhaust seem to contain a lot of steam when the engine's hot ?

 

Any of these would mean the Head Gasket's gone.

 

Jim

[Mike Fox]

I'm hoping for a simple fix on the heat exchanger or something simple too, but I'm not that lucky with this boat.

 

Oil remains black, and no steam, Jim.

[Jim]

Good.

 

Keep em crossed for cheap & simple.

 

Rather like MYSELF 

[gjb]

You will upset a lot of Welsh anglers having a lost leek    

[Stuie]

Good luck Mike...

[Leicester Fisheagle]

Hope to hear it is all sorted when we get back from France.

 

Allan.

[shytalk]

Was there coolant in the bilge below the engine if yes then there must be an external leak on the engine/pipework if no sign of coolant it has to go somewhere so either into oil into exhaust with raw water or even into the calorifier check the water coming out of the hot tap !!!!!

[Mike Fox]

Looks like the coolant is leaking from the calorifier. With this removed from the circuit, and a simple connector pipe fitted, the pressure test showed no leaks in 7 hours this week.

 

I did gentle sea-trials today, in the marina...then down to the bridge...and finally a short trip to Old Harry, and all seems ok.

 

No fishing alas! Maybe next trip!

 

I now need to have the calorifier pressure tested for absolute proof. then work out how to extract/replace it. This feels expensive and slow

 

Mike

[Steve S]

At least you have it nailed down Mike and it's not the engine.

 

Back to boiling kettles....

[Rob]

This feels expensive and slow

 

Don't be so mean about Fiesty!

 

Glad you have identified the issue, can you leave the busted one and relocate a new one to another location?

 

Rob

[mw]

Man up wash in cold water

mark