overflow bottle or wiper wash reserve?

On my 67 FHC, I apparently don’t have an overflow bottle hooked into my coolant system…that, or the bottle that the wiper fluid is in is it…since the wiper spray doesnt apparently work (or ever work that well) couldnt I just route the radiator overflow hose into the coolant bottle? thoughts? thanks.
man…it’s really starting to get cold here. I spent yesterday putting fresh oil and coolant in and it was approaching 20 degrees before the evening was done. :blush: (I use this oops icon as the “cold” icon)

p.s. where is the overflow bottle supposed to be attached?

Positioning of the expansion bottle could depend on what radiator you have. The very early rads had filler caps in the middle (do not know where the bottle goes) All the later radiators that I have seen have the filler cap on the carburettor side and the bottle usually sits in front of the rad by the air filter.
If you look at my website picture for the air filter you will see a picture of the expansion bottles location on the later Elans.
If your wiper spray does not work very well or its missing you can buy the plastic bag type reservoir with motor attatched to the bottom or the motors are available seperately. Its either that or a blockage/leak in the pipe or jets.
Clive

  • don’t think the early ones had a bottle at all ! The overflow went into mother nature from the plastic hose off the filler-neck…

Dag

Yes as Dag says the early cars did not have the water recovery bottle and according to the parts list it was only fitted on the S4/Sprints.
In my experience it dosn’t work very well anyway (although I’m sure it works for some people)
I fitted pressurized expansion tanks on my cars, the radiator is fitted with a non pressurized cap and the overflow is fed into the tank, the pressurized cap is fitted onto the expansion tank. The water level in the tank is only partly filled and the radiator full, as the water expands it fills the tank and when it contracts returns to the radiator keeping the radiator full.
Brian

Jeff,
I know it has probably got nothing to do with your question, but picture is of overflow bottle I fitted into my S4.
Yes I agree it’s not OE but it fits snug in that corner. It is an aluminium drinks bottle with the centre of the inside of the cap removed to feed the tube into the bottom of the bottle, these bottles are used by cyclists.
I see Dag mentioned about the water just going back to see Mother Nature well I suppose this way it’s stops your heart missing a beat when there is a puddle of water under your car.
By the way it’s starting to get cold here in the North of England.
Doug

Hi Jeff in freezing Chicago.
I have an S3 and had the same experience you are having with the water level in your radiator.
I just installed a bottle filled it half full, as in the photo, and hooked the hose from the pressure cap into the bottle top.
It works a treat and no more topping up has been necessary since. :smiley:

Gino
S3 Elan Milano Italy

I agree with Brian, that the preferred option would be a pressurised expansion bottle and non-pressurised radiator cap.
FWIW.

Regards,

Stuart.

Something that’s always puzzled me with the type of overflow setup that’s on the later Elans- do they work? How can they possibly work?

This is the scenario:- when coolant temp gets up to 100ish, pressure in the system rises towards and beyond the 10psi rating of the filler cap which then pops its spring, allowing the hot stuff to escape into the overflow bottle. At some stage the temp reduces, as does the pressure (to less than 10psi) and, of course, the spring-driven pressure cap pops closed again. Question: - how then can the coolant in the overflow bottle possibly get past the one-way pressure cap back into the radiator?

Because the one-way pressure cap is a two way pressure cap(or should be)
I had the same problem getting my head round it a while ago…
John :wink:

Two-way pressure cap? Don’t get it I’m afraid. The cap is designed to release pressure out of the system only - not back into it too. As soon as there’s any movement of the coolant back into the radiator, the spring-driven seal inside the cap will move with it thereby sealing off the rad once again - any residual movement in the trying-to-return coolant will merely tend to close the seal even tighter!

this thread has been very helpful…to complete the round of questions, what pressure rating cap are people using? I have 7.5 pounds.
also, what thermo temp are folks using? I am using an 82 degree Celsius right now.

Rad cap 10
Thermostat 72 degrees

Regards,

Stuart.

Hatman
if you take a close look at your rad cap you may notice two concentric valves ,each in different directions,as the pressure reduces,coolant is sucked back from the overflow bottle by the inner valve…
I know it is not easy,but you will get it eventually
John :wink:

Hatman,
John is right, all radiator caps have a valve to let atmospheric pressure back into the system after the water has expanded and then contracted otherwise the hoses would collapse in on themselves, if you look at the centre of the cap (from the inside) you will see a small round valve in the centre that can be pulled inward (oppersite direction to the main spring)
Although this system when applied to to a water recovery system “should” work in theory just does’nt seem to work in practice (thats my experience anyway) hence me useing a pressurized expansion tank.
Brian

Brian

To pull fluid back into the radiator reliably requires a “recovery” cap with a second rubber seal around the neck of the radiator filler so it sucks the fluid back in from the reservoir and not air from around the cap.

The only problem is the lowest relief pressure these recovery caps seem to come in is around 15 psi ( In Australia at least) which is getting a bit above the original Lotus specified pressure of 7 or 10 psi. Above about 20 psi you can get the pump seal start to let by especially if you have not got the crush height on the seal right.

Rohan

[quote=“rgh0”]
Brian
To pull fluid back into the radiator reliably requires a “recovery” cap with a second rubber seal around the neck of the radiator filler so it sucks the fluid back in from the reservoir and not air from around the cap. [/quote

Tried that with a cap that had the rubber seal in the top of the cap, still wasn’t happy with the results (probably crush height wasn’t right) but with the pressurized expansion tank it works fine, used the expansion tanks from the Austin/Morris 1100/1300 range of cars of the 60’s. Nice little brass (painted black) tank.
Brian

Eureka! Thanks to John and Brian’s patience, persistence and ability to communicate in the words of one syllable with which I am reasonably comfortable I now understand.

I’ve had a butchers at my filler cap and - whaddya know! - you’re right, there is provision for pressure equalisation via a return valve. I am truly grateful to the pair of you - respect is doo!

Jeff, Regarding what was original, below is a pic from my S3 originally sold in Kentucky. The car is very original (except for the conversion to DHC). I think that this is how it was prepared by the distrubutor/dealer. It has two of these Tudor bottles one for the windscreen washer on the left inner fender, and one (pictured) for coolant overflow in front of the radiator. I think Doug’s installation of the aluminum bottle looks a lot better.

Having, at last, seen the light with regard to the get-backability of the overheated coolant expelled by the system I now think I know why the non-pressurised overflow bottle system that Lotus used aint very good.

When, owing to reduced temperature (and thereby pressure) in the cooling system the spring-loaded pressure valve clangs shut, the space between the radiator seal and the radiator cap ‘lid’ thereby created will, initially, create a vacuum which the expelled coolant in the pipe will fill and find its way back intio the system via the pressure-release gubbins.

However, the overflow system (pipe, bottle) not being sealed will instantly admit air, which will quickly make its way back up the overflow pipe and from there into the cooling system to equalise the pressure therein. Ergo, it’s a ‘last out, first in’ return system that has a pretty short duration as far as returning the wet stuff is concerned. Am I right?

Ermm! no I dont think that is the answer, if the end of the pipe leading from the radiator overflow pipe into the bottle is submerged in water (that has been expelled from the radiator) then it should not be able to draw air back, the vacuum created should in theory draw water back in to the radiator.
(Sorry if I am not understanding your post :blush: )
Brian