Lotus Elan

overflow bottle or wiper wash reserve?

PostPost by: chicagojeff » Thu Dec 01, 2005 7:59 pm

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. :oops: (I use this oops icon as the "cold" icon)

p.s. where is the overflow bottle supposed to be attached?
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PostPost by: cliveyboy » Fri Dec 02, 2005 7:58 am

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.
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PostPost by: Dag-Henning » Fri Dec 02, 2005 8:18 am

- 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......

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PostPost by: types26/36 » Fri Dec 02, 2005 9:29 am

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.
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PostPost by: dougweall » Fri Dec 02, 2005 9:54 am

Image

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.
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PostPost by: gino1 » Fri Dec 02, 2005 1:50 pm

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. :D

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PostPost by: stuartgb100 » Fri Dec 02, 2005 3:00 pm

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

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PostPost by: hatman » Fri Dec 02, 2005 4:04 pm

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?
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PostPost by: john.p.clegg » Fri Dec 02, 2005 4:14 pm

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....
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PostPost by: hatman » Fri Dec 02, 2005 4:36 pm

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!
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PostPost by: chicagojeff » Fri Dec 02, 2005 4:39 pm

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.
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PostPost by: stuartgb100 » Fri Dec 02, 2005 7:25 pm

Rad cap 10
Thermostat 72 degrees

Regards,

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PostPost by: john.p.clegg » Fri Dec 02, 2005 9:46 pm

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
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PostPost by: types26/36 » Sat Dec 03, 2005 1:34 am

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.
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PostPost by: rgh0 » Sat Dec 03, 2005 10:52 am

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.

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