Colin Brown wrote:
>
> I have now done some 16,000 fast & furious road miles using Valvemaster UCL
> since leaded patrol became a no-no, so I have been watching carefully for
> signs of VSR. ( BLMC 'B' 1.8 motor)
> There may be no connection, but I have suddenly found that I am losing up to
> 1.5Pints of water during a 2 hour run, previously the level would stay an inch
> or so down from the filler neck for months at a time. We have never
> overheated, but I now notice the trend particularly in slow traffic.
> I have fitted new thermostat ( 82'C) & 7psi cap, have no external leaks, and
> have lifted the open overflow so that it would not siphon. All to no avail. I
> have no sludge on Oil cap, no water in oil or oil in water.
> I suspect that the rad system is being presurised and water loss is to the
> road under acceleration, when it cannot be seen, So today I rigged a plastic
> catch bottle and sure enough in 10 minutes collected a half pint of overflow.
> I am more worried by the steady trickle of bubbles through this overflow even
> on tickover, which, I suspect may indicate that I have a slightly leaking head
> gasket or even a cracked head. Could a recessed valve seat have breached the
> water jacket, sounds unlikely?
> Next Job, to check again my rocker gaps.
> Just trying to catch it before I have a roadside problem.
> Would welcome your collective experience please.
I would suggest you obtain a cooling system pressure tester. I bought
mine at a local pawn shop that specializes in tools and such. It cost me
about $30 because the adapters were all missing. This isn't a problem
for me since the tester itself fits Minis and MGs perfectly without an
adapter.
With the tester installed in place of the rad cap, I pump up the cooling
system to about 17 pounds (after making sure it's topped up) and then
watch and wait. Even a tiny pinhole leak will soon start to cause the
pressure to decrease. A tiny leak like this may not ever leave a puddle,
since the hot coolant will evaporate before it hits the ground or the
frame. If the leak isn't apparent, continued pumping will eventually
show as a drip (I test cold).
If I suspect the leak is in the head gasket, I test with the spark plugs
out. A bright minimaglite will allow you to see into the combustion
chamber to look for coolant.
-Rock http://www.rocky-frisco.com
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