Cooling with electric fans

[peterdpps]

When I had the AC fitted I had already had power steering fitted, the Vicarage system, so had a PS pump on the ns.
To accommodate the AC I had to have an alternator fitted and the whole set up involved removing the mechanical fan and fitting a double pulley. This has worked well for the last umpteen years. Like you I have mods to make the driving experience easier to live with. List to date is, power steering, AC, central locking, XJ 40 elec seats and a better stereo. I do leave the outside alone though!

Cheers

Pete

[gungehead]

Can anyone tell me how deep the two different radiator caps are? Or when they changed from long to short, I am not convinced mine is long enough. I do seem to be losing water and I hope it is a simple issue such as it is blowing past the radiator cap because it is the wrong cap.
I have no overheating issue, the gauge sits just above 70.

Thanks

Dave

[Martec]

The simple answer is if you are not blowing water out as soon as you stop the engine then it is long enough. Just as simple, take the cap off and look at the rubber seal face, if it is unmarked then its not sealing, if there is a depression ring similar to the face in the neck of the radiator then it is.

The long answer is to use something like a vernier caliper and measure in the neck of the radiator from the top face to the raised edge, them measure the cap from the rubber face to the underside of the cap. From these you can see if the cap spring is being compressed or not (a gap).

I can nolonger remember the theory or practice of Enthalpy/ Entropy (never fully understood it) but basically by adding pressure to the to the charge of water it raises the boiling point of the water. Also when the engine stops it nolonger circulates the water and that left in contact with cast iron/ aluminium very close to the firing space of the engine gets heat soak and will expand more. That was the reason I left the electric fan on temperature stat after stopping the engine (I don't now after the loss of two batteries).

If you remove the cap after the engine has gone cold NOT WHEN ITS HOT you will have difficulty in seeing any water in the neck of the Radiator. This worried me so I fitted an open expansion tank I was amazed by the amount of water in the tank between cold and hot, it also means I can see if I have a leak in the Jacket water system.

I'm sure someone who does understand Enthalpy/Entropy can explain better.

Best Wishes

Brian

[gungehead]

The depth of my cap is very similar to the depth in the rad neck as measured by a steel ruler. There does not seem to be much of a mark in the rubber, but I have been thinking that if it is only 4psi it wouldn't make much of an indentation. There is also not much downward pressure needed to fit the cap.


Dave

[oldtimer]

Good heaven Martec, Forgotten the theory of thermodynamics. A thermodynamic quantity that changes by an amount equal to the heat absorbed or emitted divided by the thermodynamic temperature.
Coolant when raised in temperature from Zero degrees C to 100 degrees C expands by twelve per cent. There lies the problem, fill the radiator to full when cold and as the coolant heats up the per cent age expansion by volume will be dumped overboard. This problem was recognised donkeys years ago and a simple solution cured it. A supplementary tank was mounted under the wing and connected to the radiator overflow pipe. Excess fluid dumped into the supplementary tank and when the temperature dropped the fluid is sucked back into the system.

Martec, You may find that arrangement on your Marina

P

[piman]

Hello Oldtimer,

for the expansion tank system to work properly needs the correct type of radiator cap with a one way valve in the centre to allow the negative pressure generated by cooling to draw coolant from the tank back into the engine.

Personally I just partially fill the system.

Alec

[gungehead]

This may seem a silly question but I have not had a car without an expansion tank since my first Mini 36 years ago.
My 1962, mk2 does not have an expansion tank. As it is new to me and I have heard stories of cooling issues, I am regularly checking the water level and topping it up with 1/2 pint or so every time.
I have now realised that I might as well tip the water on the garage floor cut out the middle man as that is what the engine is doing with it when the water expands.
My question is - how do I know if there is enough water in the radiator as I cannot see the level when I remove the cap? If I fill it up, it will expand and overflow out of the overflow pipe leaving the water level too low to see.

Should I fit an expansion tank?

If I check the level when hot I risk being scalded when the water pressure lowers and then boils and spurts all over the place.
Or am I not thinking this through properly - I did get up early this morning!

Thanks
Dave

[Martec]

I suggest you put your specs on Oldtimer and read my last paragraph, reference 'expansion tank', Alec found the reference.

Our radiator is the old original long neck type and so can only have a 4 psi cap (it doesn't need a 7 psi cap), after years in use the rubber it is indented. The cap has the usual spring loaded big cap that we all see but also in the centre a very small (1/2") cap that can be pulled down with your finger nails which allow the water to be sucked back into the system.

My expansion tank (Oldtimer!!!!) has a straightforward cap to stop it all sloshing out, but has a small pipe to allow air in and excess fluid out. this only works if the pipe entry is at the bottom or the pipe is feed down to the bottom.

As Alec says the old way was to top the Radiator up and allow the excess to be pushed out and with no leaks there would never be a problem!

Our cars are 50 years old and if my memory serves me correctly there are about a dozen hoses, most you can't see let alone touch. So as you say Oldtimer I copied the Marina and fitted an expansion tank to monitor the leaks. With double the water content of the Marina system there is double the displacement so a bigger tank is used, Allegro before and a peugeot now.

As a retired engineer I don't trust anything so both Jaguars and Marina are 'daily inspected' before start up. 30 years of seeing failures due to lack of inspection has cured me of 'trusting to luck'.

Brian

PS you beat me to the next post Dave, so does this and Alec's comments answer your question, 'you pays your money and takes your chance'. I am a serial modifier but only to solve problems.

[ecosselynx]

Hi Dave

I follow Brian, in that my Mk2 is modified, although I don't have an expansion tank! Once in a while I top off the water and it should be 3/4 to 1 litre (this is dependent on what the ambient temperature was when last out) never had any issues since rebuilt in 99 and been all over the place. You'll find the volume your car require due to expansion with a few regular checks.

Old timer probably has the same empathy of steam tables as I have laying around some place, although can't actually think I've looked at them since I was at collage.

Follow good maintenance and periodic checks and enjoy your car.

[oldtimer]

For Martec - It's me age you know - Have put me bins on and switched the brain on - will try harder !

I hope we have all got the message on this subject for the moment.

Have had a good day today, front wheels discs and calipers off - more later

Oldtimer

[Goss]

Had an electric fan fitted to my 3.8 back in 1999 and although only covered 12,000 miles since then had no problems whatsoever. When on the move the gauge stays at 70 degrees and on the hottest day of the year a couple of years ago whilst stuck in heavy stop start traffic the temp rose to 85 degrees and the fan cuts in bringing the temp back down within 2 minutes.

Mine is wired to the ignition which means that I sometimes switch off the engine with the fan running when parking in the garage after a run, that would happen if it were the mechanical fan only.

Goss

[gungehead]

Hi Goss,
Have you removed the engine driven fan?

Dave

[Goss]

Hi Goss,
Have you removed the engine driven fan?

Dave

Hello Dave,

Yes all gone, don't miss it at all. The latest Kenlowe fan kits have a digital thermostat which I believe is better than the older one which I have but does not really matter. The original fan specified was too small so I upgraded a couple of years later. Always planned to fit a manual override switch but can see no need for one, that is what the thermostat is there for.

Regards

Goss

[vegas602]

Sorry to jump in on this post, Pete and Brian, but I am also new to Mk 2's and AC is something I had thought about (along with uprating the heater) on my 1968 340. Maybe a silly question, but is it required/wise to convert the car to neg earth first?

[Martec]

It all depends on what you want from your car, who is doing the work and how you find the car now assuming it is a runner rather than a restoration project.

I had dynamos on my early mini's (everyday car as a lad) and was glad to replace them with cars with alternators, and so the first mod was to fit an alternator and the wiring to suit (I replaced all the looms).

If you want to fit an electric Power steering pump then you will need an alternator.

A/C, I recently asked my wife who dislikes the heat if I should fit it...........no was the reply!!

Your choice, look at other posts on here as there is plenty of information and opinions

Brian