Water loss

[tertim]

I have a thornycroft T108 1.8 D the engine runs perfectly well and all temps and pressure are normal and will run for extended periods with no problems. On switching off and leaving for a few hours the fresh water header tank needs 3 to 4 litres to top it up. I have fitted an expasion tank but this has made no difference, no water is being lost to the oil or any other obvious sources. The engine is fresh water cooled with a combined heat exchanger and manifold.

Tertim

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[longjohnsilver]

I expect your header tank is finding its own level, used to do the same on mine but gave up years ago re-filling as it always returned to the same level. If it's not overheating then just keep your eye on it and then forget about it. As long as there's fresh water in the system and no overheating then it's not a problem.

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[Bodach na mara]

same problem with a watermota sea panther. I will be interested in replies.

<hr width=100% size=1>Ken Johnson

 

[paddywackcocker]

It could be due to the heat exchanger, it may have a small leek allowing the coolant when hot and under presure to seep into the raw water side but when cold and stationary no sign of loss. You can presure up the header tank (this is a tool most engineers will have and should not charge much for useing it) and check for presure drop/loss. But like it has been said it might be just happy at that level.


<hr width=100% size=1>Sorry for the spilling

 

[omega2]

We put a bottle on the end of the overflow pipe to catch the cooling fluid, but in the end had to replace the head gasket, problem solved, but we ran defective for about 2 years.

<hr width=100% size=1>J HAMER

 

[tertim]

Hi
If I don't top up the water level then the engine starts to overheat. I suspect it could be something to do with the core in the heat exchanger.

tertim

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[tertim]

Hi
Yes I'm thinking along the same lines.

Tertim


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[aitchw]

It may be totally irrelevant but an old BMC 2.2 I had suffered from weeping core plugs that had corroded leading to water loss that took ages to find.

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[longjohnsilver]

Overheating

Well in that case it's best to check. Taking the stack out of the heat exchanger isn't difficult, well worth the effort to check the tubes. Don't forget to get new O rings for the ends.

Presume you've had a good look around the engine for tell tale water/rust stains which could be fresh water leaks.

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[jeffro]

Re: Overheating

Had the same problem leading to a new cylinder head when fitted the problem reaccured on closer inspection it was the header tank pressure cap looked new but was letting by a new cap cured the problem for me four quid in Halfords good luck Jeffro

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[Becky]

We have a Thornycroft 35hp which has just lost all its water. The water pump was leaking, but the stain down the front of the engine was easy to see. I have today replaced the water pump (HWMBO had to go back to London) and hopefully that will be the problem cured. I expect you have checked something as obvious as this.
Scary how many paces the things can lose their water from, though.

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[Birdseye]

The one thing you shouldnt do is to simply ignore it. The fresh water system is sealed and under pressure - it shouldnt lose even as much as a teaspoonful a year.

If there is no emulsified oil, then that rules out a headgasket leak into the oilways. So the fresh water is going somewhere you alse cant see it. Go for the simplest problem first and carefully check all pipe joins / hoses etc for small leaks and staining.

The next most likely culprit is a leak between the fresh and raw water sides of the heat exchanger. If the raw water side drains back when the engine is stopped, any sucking back into the fresh water side as the engine cools will be air.

Best way of checking is to beg / borrow / steal the kit that garages use to pressure test car radiators. Disconnect and drain the sea water side of the exchanger, and do your pressure test. Fresh water should then come out of the sea water side.

If its none of these, but you still fail the pressure test - then it sounds like leaking head gasket into the exhaust .


<hr width=100% size=1>this post is a personal opinion, and you should not base your actions on it.

 

[brianhumber]

Re: Water loss - Pressure testing

As you are overheating and have lost water its going somewhere. As others have said favourites are heat exchanger, pump, core plugs. Don't forget any engine supplied calorifier.
If you cannot find a chap to lend you a pressure tester its easy to DIY. Remember the old basic formula - pressure equals roe times g times head.
Rig up with a modified pressure cap a tube attached to a long of hose fixed into a bucket full of water. Hoist bucket up mast to the correct height for the pressure you want and you have put your water system under working pressure. Take off sea pipe connections into heat exchangers to see if any leaks past seals etc at your convience. Take the heater plugs out and turn over to see any water leaking into internals.






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