Where's my water going now?

[alun n]

It doesn't; as the coolant cools it contracts and presure reduces naturally. Pressure by volume divided by temperature is a constant (Boyle's Law).<br>
<br>
If he system isn't working correctly then pressure over13psi escapes via the cap or a burst somewhere...

<p></p><i></i>

[Leeds Sprint]

Alun<br>
<br>
I think the cold water pressure I'm getting in my system is caused by air then. When I remove the overflow cap when the cold, the escaping water seems to be propelled by a fair bit of air. I can see quite a lot of air escaping from the engine and up into the expansion bottle when the cap is removed.<br>
<br>
Is it possible that Jonners suggestion of air being drawin into the system from a pin whole leak is presurised by the motion of the water pump? This air then collects somwhere in the system where it cannot escape again through the same pin hole, so this pressurised air is trapped. When the overflow cap is removed much of this presurised air escapes, but leaving behind pockets of low pressure air. These pockets of un-displaced air are trapped and not allowing the water from the overflow to return to the cooling system.<br>
<br>
This is all very complecated for me. But I must find the source of the presure. I think my hoses must be under considerable strain.<br>
<br>
Thanks<br>
<br>
Chris

<p></p><i></i>

[MaddMart]

Pin hole is possible but if air can get in/out, so can water.

<p>Martin<br>
<br>
<!--EZCODE LINK START--><a href="http://www.dolomitesprint.com/" target="top">www.dolomitesprint.com</a><!--EZCODE LINK END--></p><i>Edited by: <A HREF=http://p206.ezboard.com/bthetriumphdolo ... addMart</A> at: 13/9/06 7:54 am<br></i>

[Leeds Sprint]

That's what I'm thinking Mart. <br>
<br>
I think I will be replacing my hoses because the ends look a bit worn and crumbly in places, but they are not leaking any water that I can see at all. I think the water loss I was getting before was exiting through the overflow bottle cap and out the overflow spout due to a faulty spring in the cap.<br>
<br>
My garage gave me a new overflow cap from annother car. They had to pry open the small metal fixings that allow the cap to be screwed onto the top of the expansion bottle. This new cap is rated at only 7lbs, but it seems to be having no problems retaing the high pressure water and air.<br>
<br>
Is it possible that this improvised cap is creating the one-way valve situation, so that air is sucked in through a weak seal but cannot escape in the same way? <br>
<br>
Chris

<p></p><i></i>

[redrichie]

<!--EZCODE LINK START--><a href="http://www.rimmerbros.co.uk/cgi-bin/rim ... ling">Full hose set at Rimmers</a><!--EZCODE LINK END-->.<br>
<br>
Well, to put this one to bed and see once and for all where the problem is, get the full hose set and change them one by one until you find the problem. Forty-odd quid isn't that much for complete peace of mind, plus you can keep the good old ones as spares I guess. The kit includes all the jub clips as well if i remember correctly.

<p></p><i></i>

[davepoth]

It might well be that the system is only leaking when it's pressurised. I had that with an MG midget once.

<p></p><i></i>

[Leeds Sprint]

Ritchie.<br>
<br>
Hoses are already on order. So is the proper Dolomite expansion bottle cap. I hope that solves my problem.<br>
<br>
Dave,<br>
<br>
I'm not actually loosing water anymore now that I have a radiator cap that seals properly. Its the build up of pressure (that is retained even when cold) that concerns me. The water that is displaced into the expansion bottle that cannot return into the engine is reducing the cooling ability of the system.<br>
<br>
Chris

<p></p><i></i>

[Jon Tilson]

If the expansion tank is retaining pressure on a COLD engine you must have some bizarre internal collapse on the hose to the tank thats acting as a one way valve.<br>
<br>
I would change this hose first before paying 40 quid to Rimmers.<br>
<br>
I have dollies with 30+ year old hoses that dont give any trouble...<br>
<br>
I'm afraid my experience of new hoses is generally not good. Old NOS ones from auto jumbles are far better.<br>
Preferably covered in french chalk and with Unipart or some such stickers.<br>
<br>
The cap should be 13lb.s<br>
<br>
<br>
<br>
Jonners

<p></p><i></i>

[Sprint36]

A quick check could be done by undoing the thermostat cover plug when cold to see if the whole system is pressurised or if it's just the expansion tank retaining pressure. The small expansion hose is not shaped so could be purchased as a length from any motor factor.<br>
<br>
David

<p></p><i></i>

[Leeds Sprint]

Hello All<br>
<br>
I recieved a lot of useful advice from many club members last weekend in Hatton about the high levels of preasure I have been getting in my cooling system. Thank you very much to all of you. You really helped me to speak more clearly to my garage about the symtoms and problems I have been having. <br>
<br>
My garage found that there was slightly less compression on the front cylinder, and there was a small reading of exhaust gasses in the coolant as well.<br>
<br>
Upon re-torquing the head studs they found that the front bolts were a bit more slack than the other ones. After tightening the studs they found that there was a corresponding reduction in the exhaust gases reading.<br>
<br>
I have had a new cap and a few new hoses fitted as well. <br>
<br>
I hope that this solves my over-preasurisation problems that I have been having, and that I no longer loose so much coolant out of my expansion bottle overflow. I also hope to see the excess water in the expansion bottle return to the engine as it cools. Previously it would just sit there full to the top and retain its presure even when cold. <br>
<br>
I think it will take a few days for me to be sure that the problem has been solved. Thanks again for all your help.<br>
I'll keep you posted on how things are going.<br>
<br>
Chris

<p></p><i></i>