Distributer. Water loss.

[Brian Cole]

Last weekend I went down to Brighton in the Jupiter to meet a new friend who now drives a car that I used to own in the Fifty's, my very first car in fact, and also to watch the spectacle of the Veterans on their way to the seafront. The cars leave the main road and take a detour along the old route through Staplefield Green, an attractive vantage point to see them intimately as they pass by through a magnificent assembly of Vintage and Classics parked up on the green to watch the show.
The Jupiter gave me a few anxious moments on the journey due to intermitent missing when the engine was revving or under load as it was frequently, with the many short sharp hills on that route. It gradually became worse on the way home a day later. Today I had a look at it.
I removed the distributer cap to find that the base plate was shaking arround. The two screws that hold the base plate to the distributer body had come loose, no spring washers as reccomended in the manual, so I have now fitted them and the pick up seems more positive. No doubt this accounted for the erratic performance and I now wonder if it may also have been partly responsible for the 'jingling" noises that I have beeen hearing, we shall see.

I have also been having a problem with the engine dumping a couple of litres of water from the radiator overflow pipe once it has reached opperating temperature. I have removed and checked the thermostat which starts to open around 80 degrees, it has a small bleed hole with a tapered valve which I assume closes when the pump is running during warm up . i do not understand why this should be happening. The low water level does not seem to cause overheating but of course makes a nonsense of the water temperature gauge which starts at 75 degrees on warm up and then suddenly shows 30 degrees as the radiator dumps the water and remains so until I refil with water and then repeats all over again. I would like to get things right and will be grateful for any comments or advice from our members.

[Leo Bolter]

Brian.

Please see http://jowett.net/forum/viewtopic.php?f ... 016#p12016 regarding the water loss part of your post.

Cheers.
Leo.

[Keith Andrews]

couple of litres of water from the radiator overflow pipe once it has reached opperating temperature.

These days cars have 'green' tree hugging overflow bottles with special caps so when the water expands , it goes into the bottle and when the engine cools is sucked back in....
Most old cars if one looks close have a "hot" and a "cold" fill level.
But if y fill up the radiator with coolant..near to top and cold...drive it, let the execess overflow....not the level when cold and mark it
Next time when checking the level when cold check against your mark
No more water over flow

Thermostat....that little hole is a by pass...has several functions
1/ always some water flow and prevents the water pump caviting
2/ If there was no water flow, there would be no movement of the hot water (or very slow movement) to the thermostat to heat it and open it...this would then result in water boiling very quickly around heads and cylinder walls causing hot spots and very high presures back into the radiator and blow water everwhere...basically runing a engine with no water pump.
3/ most thermostats are at a high piont in relation to the engine, doing so alows and traped air to flow thru and help prevent air locks

If u have a sudden change in temp when the cap opens and dumps the excess water....this will be are result of a higher pressure, then when pressure is released a sudden temp change...
This is assuming uhave not a blown head gasket...which will do the same thing.

That little often over looked thermostat, is so often taken for granted...underestimated its importance
Hence why oneshould have not any old corect temp thermostat but the corect one for that engine....there are other specs like flow (hole size) when open....some engines ..like a sb Chevy, will run very hot without a restriction to flow...and rate of opening which relates to oil temps etc.

[Brian Cole]

You guys may be a long way away, but you are certainly hot off the mark! Many thanks for your interesting comments, some of which have reinforced thoughts that I have had. If I have a gasket problem, which would not be unusual for a jupiter, it must be a slight leak, the engines performance being better than it has for some time, but possibly enough to pressurise the water jacket before the thermostat opens resulting in a sudden gush of air or water. So this morning I'm going to take the top hose off again and remove that little valve and see what happens. As they say I will keep you posted.

[Keith Andrews]

If y suspect a blown head gasket.....
The engine generally runs hotter than normal
If u pull a spark plug, the pot that has the blown gasket is very clean, and clean inside the combustion chamber if look with a torch
If theabove hasnt occured u can be pretty sure not blown head gasket.
Further check a compression test, thu this is not always show low compression
And the only real sure way is a COx/HC gas test on the radiator...takes 5 mins at the local workshop...usually Free.