BMC 1.5. Drinking water

[Darren72]

Its started to use water. About 1/2 litre in 8 hrs of steady chugging. Checked the oil and cant see any sign of water in there. Not had the proper chance to check all water pipes due to a metal bulkhead that needs removing to get access to all of the engine. What should I do? Obviously run the engine and check all water hoses. What else? Head gasket gone? Still runs the same as it has for the last 3 years. Noticed a slight increase in oil pressure but only occasionally.

[RLWP]

How do you know it is using water (and that isn't a silly question)

 

Richard

[Darren72]

Header tank showed nearly empty. Never seen it so low. Always usually just below max line. In the 3 years we have had the boat I have rarely topped it up. But over the past 2 weeks it has steadily drunk more. I did have a hose replaced a few months prior to our 2 week trip. Thats my first port of call. Not noticed any excess water in the bilge though.

 

 

Should have asked you to take a look on the Sunday morning of the banter at Alvecote if I had thought. 8.30 am bet you were still stuck to your pillow. Unlike some who were madly waving out of the window as we past.

Edited August 13, 2014 by Darren72

[RLWP]

'fraid so - I think I heard a boat about then...

 

Always a good place to start, the last work done

 

You are looking for a small leak here, not a gushing torrent. It might show up as discolouration, or rusty marks rather than a wet bit

 

Richard

[Darren72]

Ta. Richard. Next time aboard I will have a good gander.

[Tony Brooks]

Have a very good look at the core plugs in the block. They are round disk things. If you see a rusty crust or stain it needs renewing, they do rust through in time.

[Darren72]

Easy to replace Tony? I have a manual. Should be clearly identified i am sure

[David Mack]

Easy to replace Tony? I have a manual. Should be clearly identified i am sure

When it happened to me it was more difficult to get the old one out. In the end I put a wood screw through the pinhole in the old plug and pulled it out with pliers. The new one I tapped in with a short length of dowel between the hammer and the plug.

[gazza]

When it happened to me it was more difficult to get the old one out. In the end I put a wood screw through the pinhole in the old plug and pulled it out with pliers. The new one I tapped in with a short length of dowel between the hammer and the plug.

That's a fair way of getting it out, a claw hammer works well space permitting.

 

I prefer to knock the new one in with a socket slightly smaller than the od of the plug. Avoids the slight risk of deforming the plug.

[chris63]

I am no expert bit is it possible that it could have been a air lock from when the pipe was changed?

[David Mack]

That's a fair way of getting it out, a claw hammer works well space permitting.

 

I prefer to knock the new one in with a socket slightly smaller than the od of the plug. Avoids the slight risk of deforming the plug.

Agreed. The dowel I used was a reasonably close fit inside the plug for the same reason.

[Alan Saunders]

I had no problem removing the core plugs from my 1959 Austin A35. In a cold spell circa 1969 they were frozen to the ends of drooping, cylindrical 'icicles' emerging a couple of inches from the block. Normally I drained the coolant (water) overnight.

 

As I remember it, the core plugs were domed steel. After defrosting the engine and cleaning the core plugs and their seats I added sealant (probably Hermetite red) and drove the plugs in with a soft hammer and a box spanner drift. Finally, a few blows in the centre of the dome with a half inch diameter brass drift to expand the plug into the block but not dent it.

 

Back then, at ~20 years old I 'knew it all' and got lucky. I don't have the same confidence today but I think expanding a domed core plug was a good strategy. Of course, better sealants are (were) available, e.g. Hylomar?

 

Alan

[Tony Brooks]

The OP may have domed core plugs or flat, flanged Welch plugs. Fitting of both types has been explained above. From what I hear getting the correct size is important so measure the old plug or its hole. However there is every chance it is not a plug. It could be the water pump seal so its a question of looking for looking for rust or antifreeze stains.

[RLWP]

I am no expert bit is it possible that it could have been a air lock from when the pipe was changed?

 

Yes, except that would have shown up pretty quickly with the same symptoms as a failed head gasket - lots of boiling from the header tank. The thread title would be far more dramatic for a start

 

Richard

[Darren72]

Ta folks. I will check next weekend hopefully and update accordingly.

[Darren72]

Cant find the core plugs? To be honest not looked in the manual where they are but I cant see owt thats rusty nor can I see a leak. But its still using a 750ml - 1lt after a good days chugging. Bloody baffles me. Even bleeded the skin tanks if that will do owt.

[Tony Brooks]

If there is any air trapped in the system it will expand when heated more than water and will thus expel more from the header tank. The header tank on a BMC 1.5 is usually the exhaust manifold unless someone has fitted another or its an ex Calcutt hire boat. many people will tell you that the correct water level in the cold header tank is 1" below the filler neck and this is correct for a heat exchanger engine. it is far from correct for a skin tank cooled engine because they hold far more coolant AND the skin tank is of an unknown size. The only way to get the correct level is to fill to the brim once and go for a good long run. The excess water will then be expelled so when the engine cools the level will be correct, sometimes you can only just about feel the water.

 

As you say the apparent excess water use is only recent the most likely explanation is an pocket trapped somewhere except that would result in water being expelled form the filler so would end up i the bilge or engine drip tray. However I think you stated that no water is found in the bilge or drip tray. If you are sure that there are no leaks then that suggests three other possibilities.

 

1. An internal leak in any calorifier engine coil but that usually causes water to keep pouring out of the engine filler because of domestic water pump pressure.

 

2. An external leak in the ski tank. It may be more of a weep that mainly shows itself when the system is under pressure. I think you need to hire or borrow a cooling system pressure tester and put the cold cooling system under pressure. If the pressure drops you have a leak.

 

3. An internal leak in the engine (head gasket, cracked bore) but these usually present them selves as running hot & overheating.

 

I somehow feel we have not been much help on this one.

[MtB]

If the water pump is anything like that on an A -Series petrol engine, and I think it is, then they are terribly prone from memory to slow water loss from bearing wear leading to the shaft seal leaking slightly.

 

As a yoof I remember driving Minis which needed the cooling water topping up daily and a new water pump usually fixed this. As a speculative repair I'd change the water pump anyway if I were you as it's easy and I doubt they are expensive, and it will rule out the water pump as a suspect.

 

Half a litre of water lost over eight hours of cruising time is so slow it will dry up on a hot engine as it escapes so don't expect to find a puddle of water lying under the leak.

[alan_fincher]

As a speculative repair I'd change the water pump anyway if I were you as it's easy and I doubt they are expensive, and it will rule out the water pump as a suspect.

If the pump is leaking enough to lose the three quarters to one litre a day being mentioned, it should surely be possible to see it, without needing to change the pump as a speculative thing?

 

At the very least a container positioned below it should surely establish it one way or the other.

 

EDIT: Just noticed bit about you thinking it will evaporate away - I don't think it will, as the temperature of the water dripping from the (low down) pump will be only 70 or 80 degrees, so I think it will remain very much water, and be seen to be dripping.

 

 

Also, if the header tank just has one of those short brass drain pipes where the pressure cap goes on, and that is not connected to any kind of external overflow bottle, I would put a length of plastic hose on, and run it temporarily into an old milk bottle or similar. That should prove whether or not any water is being pushed out here as the engine is running. I'm tempted to think this could be the case, perhaps because of an airlock somewhere. Is failing head gasket a possibility, though??

Edited September 18, 2014 by alan_fincher

[rrt2]

Put some food dye in the cooling system - it will show where the water is coming from.

[Tony Brooks]

EDIT post 17.

 

Its a skin tank, not ski tank.

 

Of more importance re item 2. How does the water level in the header tank compare with the water line on the boat?

 

MtBM's post about any leak evaporating is why I suggested pressure testing a cold engine.

[Chalky]

 

Yes, except that would have shown up pretty quickly with the same symptoms as a failed head gasket - lots of boiling from the header tank. The thread title would be far more dramatic for a start

 

Richard

 

When the head gasket went on my MGB (1.8 litre B series) there wasn't any gushing boiling water. What I noticed was pressure in the header tank when the engine was cold and disappearing coolant. It didn't loose much, just enough to be noticeable. I changed the head gasket and the problem went away. I was baffled originally about what the cause was and was given the solution by one of the fitters in the flight shed at Longbridge.

Edited September 18, 2014 by Chalky

[MtB]

EDIT: Just noticed bit about you thinking it will evaporate away - I don't think it will, as the temperature of the water dripping from the (low down) pump will be only 70 or 80 degrees, so I think it will remain very much water, and be seen to be dripping.

 

My experience of A Series engines (and also small leaks on central heating systems) suggests otherwise. A slow leak meeting hot metal tends to evaporate rather than collect in a pool.

 

The water pump with a worn bearing also only leaks water when it is running, and as it drip downwards it meets a spinning pulley and gets sprayed everywhere or atomised. Don't forget we are looking for one drip of water every five or ten seconds, not a trickle. still only a suggestion though. I've spent many an hour chasing similar leaks on Minis and it's usually the water pump!

 

MtB

P.S. It's just that if the OP is gonna start with spannerwork having ruled out core plugs, the water pump is an easier option than the head gasket!

[Alan de Enfield]

 

.....solution by one of the fitters in the flight shed at Longbridge.

 

Did you ever get down into the cellars/tunnels at Longbridge and see the aircraft bits and pieces, jigs etc ? - Amazing !!

 

I always thought the "Elephant House" aptly named.

[J R ALSOP]

What make is the builder? only I came across twice a Colecraft with twin skin tanks that were connected with a angle iron welded across the front bulkhead. It had rusted through the bulkhead and was filling up under the cabin floor. They were a big job to repair.