Water loss..but where?

[Antonnick]

My Herald 13/60 , awakened from its winter sleep is performing like a new car. You only have to turn the ignition key and it seems, without the starter motor springs into life. Was not always so and thanks to the help of this forum in the past it has had numerous renovations to the motor, reground crankshaft, head refurbished etc. I mention all this because I am worried about the water loss. We went on a good round trip yesterday to the (for the British) famous Edersee damn, a round trip of about 200km and this morning the rad needed topping up with about a half to 3/4 litre. This is the second time this year . I have checked all the obvious hose connections and they seem to be ok.

When I removed the head a couple of years ago, cylinder no4 was shiny whereas the other 3 were carbonised. "steam cleaned" is what someone here commented at the time. I am worrired that , depite the smooth tickover and excellent performance of the engine at all speeds, that this my be occuring again.

Is that possible when the engine is running so well? 

I would wellcome some ideas of what to look out for. It has an after market aluminium rad , by the way.

Gruß / regards

Antonia

[yorkshire_spam]

It's possible that a head gasket issue is causing the engine to lose coolant into the "steam cleaned" cylinder. If that's the case I'd expect to see some steam from the exhaust, although so far it might be so little that it's hard to see. You could consider a chemical test on the water for combustion products - a simple relatively cheap kit helped me diagnose a similar head gasket issue on my Dolomite. 

Another possibility is the water pump. I've had very mixed experiences with them on my Spitfire, so leaking after a very short period of time. Check around that area for any tell-tale signs of dried out coolant. 

[glang]

The problem can be that theres a small leak somewhere (even water pump seal as suggested) but only under pressure so when the coolant comes out it turns to steam straight away and leaves no indication.

Its possible to pressurise the system cold with a special radiator cap and hand pump then any leakage will be in liquid form and easier to spot. I have done this but by connecting a pump to the radiator overflow pipe with the normal cap still in place. Then if the cap has a good top seal you can carefully pressurise the system and have a good look round. Obviously keep the pressure below the cap lifting value and note that the system should hold it so be wary when later undoing the cap as although not hot coolant will still tend to shoot out!

[Antonnick]

Many thanks to you both for the Blitz replies - I had not expected to read anything so quickly. 

I intend to inspect the Waterpump and do Glangs' pressure test later on --when it stops raining.

[glang]

When doing the test be careful not to over pressurise the system as the radiator cap obviously wont protect it and you could burst something!

[Antonnick]

I sort of managed a pressure test and maybe the bottom hose connection to the rad was a bit damp as a result- could just as easily have been condensation though. However, I was able to tighten the hose clip somewhat so perhaps.....

I will drive it around the next few days and check again.

[glang]

Yes Ive had lots of problems with hose connections (I too have an after market ally rad🤔) and it takes several retightens before my overflow pipe to the water bottle will stay full consistantly when leaving the car unused for a while...